Informant Accuracy of IQCODE, AD8 and GPCOGi for diagnosis of dementia: Does your friend know best?

Informant Accuracy of IQCODE, AD8 and GPCOGi for diagnosis of dementia: Does your friend know best? | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Informant Accuracy of IQCODE, AD8 and GPCOGi for diagnosis of dementia: Does your friend know best? Jasmine Chingono, Samuel Thomas Creavin, Mark Fish, Sarah Cullum, and 3 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-4637777/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 15 Apr, 2025 Read the published version in BMC Primary Care → Version 1 posted 4 You are reading this latest preprint version Abstract Background Increasing numbers of people are requiring evaluation for possible dementia. There has been limited research exploring the accuracy of informant questionnaires in primary care. Methods A diagnostic accuracy study to explore the influence of informant relationship type on the accuracy of IQCODE, AD8 and GPCOGi in primary care. 240 participants were recruited from 21 general practitioner (GP) surgeries in the South West of England. The reference standard for a diagnosis of dementia was made against ICD-10 criteria based on specialist clinician assessment. A threshold of greater than 3.3 on IQCODE, greater or equal to 2 on AD8 and less than 5 on the informant component of GPCOG (GPCOGi) was used to indicate an abnormal test. Results Of 238 participants with informant data, 131 had dementia, 60 CIND, and 47 had normal cognition. Median informant age was 70 years (IQR 60 years to 78 years). 71% of informants were female and 56% of informants were spouses. On all three questionnaires, compared to spouses, adult descendants tended to score participants more cognitively impaired, whereas friends scored participants less cognitively impaired. However, there was little evidence of difference by informant relationship type once fully adjusted. Overall accuracy was similar for all three informant questionnaires with an AUROC of 0.67 (95% CI, 0.62 to 0.72) for IQCODE, 0.64 (95% CI, 0.60 to 0.69) for AD8 and 0.59 (95% CI, 0.56 to 0.63) for GPCOGi. Friends tended to have the highest AUROC at 0.89 (95% CI 0.78 to 1) for IQCODE, 0.88 (95% CI 0.77 to 0.99) for AD8 and 0.69 (95% CI 0.57 to 0.81) for GPCOGi. This difference was significant for IQCODE (p=0.0004) and AD8 (p=0.0001). Conclusions Most informants were either a spouse or adult descendant. Overall, informants, when using IQCODE, AD8 or GPCOGi may be useful at ruling out dementia but less useful for ruling it in. We found no evidence of difference between spouse or adult descendants but friends (while accounting for only 8% of informants) performed significantly better overall on IQCODE and AD8 due to an increase in specificity without loss of sensitivity. Dementia informant relationship accuracy IQCODE AD8 GPCOG primary care Figures Figure 1 Introduction Dementia is a syndrome of progressive, cognitive symptoms including memory disturbance, difficulties with language, executive function, visuospatial skills and changes in behaviour [ 1 ]. Timely and accurate diagnosis allows patients and their carers to access appropriate medication, services and engage in advanced care planning [ 2 ]. However, the path to a dementia diagnosis can be lengthy, with patients and their carers experiencing considerable uncertainty and a lack of patient-centredness [ 3 ]. Many people living with cognitive problems do not have a formal diagnosis of dementia, and pressure on diagnostic pathways is anticipated to increase in future [ 4 , 5 ]. In the United Kingdom, a dementia diagnosis can require referral to a specialist dementia diagnostic service, and the role of primary care in supporting a more effective pathway to diagnosis is a priority research area [ 6 , 7 ]. An informant is a person close to a patient, such as a family member, friend, or caregiver, who can provide additional information to aid diagnosis. The use of a structured informant questionnaire is advocated by the National Institute for Health and Care Excellence (NICE) as part of an initial assessment [ 6 ]. Examples include the Informant Questionnaire on Cognitive Decline in the Elderly (IQCODE), AD8 and General Practitioner Assessment of Cognition (GPCOG) [ 8 – 10 ]. GPCOG, designed for use in a primary care setting, consists of two parts and includes a component for the informant to complete (GPCOGi) [ 10 ]. All three informant questionnaires ask the informant to rate the patient’s performance on several cognitive indicators compared to several years ago. A recent overview of informant questionnaires for dementia concluded there is currently only sufficient evidence to justify the use of IQCODE and AD8. However, it also highlighted that there is little evidence available for their use in primary care settings despite test performance varying by setting and primary care being an important setting for identifying cognitive impairment [ 11 ]. Informant characteristics may affect scoring and therefore accuracy of informant tests. For example, a study found that wives with more anxiety or depressive symptoms tended to rate more cognitive impairment in their husbands on the IQCODE [ 12 ]. However, previous studies suggest that IQCODE scores are not influenced by length or type of relationship, age, or educational status of the informant [ 12 , 13 ]. These studies examined associations between tests scores and relationship types, rather than test accuracy, which is more clinically relevant. The aim of this study was therefore to address these research gaps by exploring the diagnostic accuracy of IQCODE, AD8 and GPCOGi in a primary care setting, and whether this differed by informant characteristics, particularly relationship type. Methods This was a prospective diagnostic accuracy study. Population We recruited participants between March 2015 and May 2017 from 21 general practitioner (GP) surgeries in the Bristol, North Somerset and South Gloucestershire (BNSSG) area in the South West of England. This covered a diverse area around the city of Bristol, with a total population of around 900,000, with 12% aged over 70 [ 14 ]. Inclusion and Exclusion Criteria We included people aged over 70 years who were seeking evaluation for concerns about cognition but did not have an existing formal diagnosis of dementia. We did not specify the nature or severity of the cognitive symptoms, but these must have been present for at least six months, and reported by the person themselves, someone close to them or a healthcare professional. We required that an informant attended the research clinic as a criterion for participation, to enable robust diagnosis. We excluded people with a known neurological disorder (including Parkinsonism, multiple sclerosis, learning disability, and Huntington’s disease), a psychiatric disorder requiring secondary care input, those registered blind, profound deafness preventing the use of a telephone, those with rapidly progressive symptoms and those with advanced cognitive problems unable to consent. We encouraged GPs to refer all consecutive eligible patients regardless of their clinical judgement or any initial test results. Further details have been reported previously [ 15 ]. Index test We asked informants to complete the IQCODE-16, GPCOGi, and AD8 during the research clinic visit, facilitated by a single GP and performed as outlined by the original authors [ 8 – 10 ]. The facilitating GP was not aware of any other clinical information related to the participant or informant. The IQCODE-16 asks the informant to rate the patient from 1: “much improved” to 5: “much worse” now, compared to 10 years ago, across 16 questions and a mean score calculated. The original version of IQCODE consisted of 26 items. A short form, consisting of 16 items was subsequently developed and found to have comparable validity [ 8 ]. AD8 consists of eight questions assessing whether for each statement there has been a change in the last several years caused by cognitive problems. Response options are: “yes, a change”, “no, no change” or “N/A, don’t know”. Answers “yes, a change” score 1 and other responses do not score. The AD8 can be completed by a patient or informant [ 9 ]. Unlike IQCODE and AD8, GPCOG includes both a patient and informant component. The informant component consists of six questions asking the informant to compare the patient to how they were a few years ago. Response options are “yes”, “no”, “don’t know”, “N/A”. All responses except “yes” score 1 point [ 10 ]. Only the informant scores were used for analysis in this study. We refer to this as GPCOGi. We used a threshold of > 3.3 as a threshold for an abnormal index test on IQCODE (mean scores range 1–5; higher scores indicating worse cognition). This reflected the threshold used for the pooled analysis in Cochrane systematic review [ 11 ]. A threshold of greater or equal to 2 on AD8 (scores range 0–8; higher scores indicating worse cognition ) and < 5 on the GPCOGi (max score 6, lower scores indicating worse cognition). We categorised informant relationship types as spouse, adult descendant, sibling or friend, and collected information on informant age and sex, all based on self-report. Reference standard A single specialist physician assessed participants over approximately one hour using a clinical history, Addenbrooke’s Cognitive Examination III (ACE-III), Brief Assessment Schedule Depression Cards (BASDEC) and the informant-completed Bristol Activities of Daily Living (BADL) Questionnaire. The specialist physician did not use specific thresholds for these measures and was not aware of any GP judgement, other test results or investigations. The specialist used their integrated assessment to consider a dementia diagnosis according to ICD-10 criteria [ 16 ]. The same specialist physician could also assign a diagnosis of Cognitive Impairment Not Dementia (CIND) if they felt their assessment met the criteria for Petersen mild cognitive impairment, or another cause of cognitive impairment such as traumatic brain injury or affective disorder [ 17 ]. We reviewed medical records for all patient participants six months after the research clinic to find subsequent information that would contradict the initial research clinic judgement. For borderline cases a second independent specialist reviewed initial assessment as well as the medical record to determine a final diagnostic classification. Statistical methods We summarised information on participants and the variation across cognitive categories and informant types. We used linear regression to test the hypothesis of no association between continuous informant test score and categorical informant type (adult descendant, sibling, friend), compared to spouse as the baseline category. We derived diagnostic accuracy parameters with 95% confidence intervals for informant tests at pre-specified thresholds (see Index Tests) compared to reference standard dementia as determined by specialist assessment. We calculated sensitivity and specificity of informant tests at these thresholds in subgroups to derive accuracy by informant type and sex. We used logistic regression and t tests to investigate potential associations between a missing informant score and informant relationship type, age, and sex. We used Stata 15 for analysis. Results Participants We recruited 240 participants. Figure 1 shows a flowchart of study inclusion. We had demographic information available for 238 informants, and of these 231 completed IQCODE, and 238 completed AD8 and GPCOGi. The specialist classified all 240 patient participants according to the reference standard: ‘dementia’ (n = 132), ‘CIND’ (n = 61) and ‘normal’ cognition (n = 47). For the 238 who also had informant information, the specialist classified the patient-participants as: ‘dementia’ (n = 131), ‘CIND’ (n = 60) and ‘normal’ cognition (n = 47). Table 1 summarises informant characteristics and informant questionnaire score by participant cognitive category according to the reference standard. The median informant age was 70 years (IQR 60 years to 78 years). Informants for people with dementia tended to be younger (median age 69 years) than informants for people with normal cognition (median age 71 years) or with CIND (median age 73 years). Most informants were women (71%), and this was similar for patients categorised as having dementia, CIND or being cognitively normal. The most common informant type overall was spouse, 56% (n = 134). People with dementia were more often accompanied by an adult descendant (43%) than people with CIND (28%) or normal cognition (15%), OR 4.3 (95% CI 1.7 to 11; p = 0.0006). Table 1 Characteristics of informants by patient participant cognitive category Cognitive category Informant Characteristic Dementia a (n = 131) CIND b (n = 60) Normal cognition (n = 47) Median age of informant at clinic, years (IQR) 69 (59–78) 73 (58–77) 71 (65–77) Sex (column %) c Male n = 62 (26) 37 (28) 13 (22) 12 (26) Female n = 169 (71) 93 (71) 46 (77) 30 (64) Informant type, n (column %) Spouse n = 134 (56) 69 (53) 36 (60) 29 (62) Adult descendant n = 80 (34) 56 (43) 17 (28) 7 (15) Sibling n = 4 (2) 2 (2) 2 (3) 0 (0) Friend n = 20 (8) 4 (3) 5 (8) 11 (23) IQCODE Mean IQCODE median score d (IQR) 4.3 (3.8–4.6) 3.5 (3.3–4.1) 3.25 (3.1 to 3.4) People in each cognitive category whose score exceeded the abnormal IQCODE threshold, for each informant type, n (%) e Spouse (total n = 129) 63 (91) 25 (78) 15 (54) Adult descendant (total n = 80) 56 (100) 13 (76) 5 (71) Sibling (total n = 4) 2 (100) 1 (50) 0 (0) Friend (total n = 18) 4 (100) 2 (50) 1 (10) AD8 AD8 median score f (IQR) 7 (5–8) 4 (2–6) 2 (0–3) People in each cognitive category whose score exceeded the abnormal AD8 threshold, for each informant type, n (%) g Spouse (total n = 134) 65 (94) 26 (72) 21 (72) Adult descendant (total n = 80) 56 (100) 16 (94) 5 (71) Sibling (total n = 4) 2 (100) 1 (50) - Friend (total n = 20) 4 (100) 2 (40) 2 (18) GPCOGi GPCOGi total median score h (IQR) 1 (1–3) 3 (2–4) 4 (3–5) People in each cognitive category whose score exceeded the abnormal GPCOGi threshold, for each informant type, n (%) i Spouse (total n = 134) 68 (99) 32 (89) 22 (76) Adult descendant (total n = 80) 56 (100) 15 (88) 5 (71) Sibling (total n = 4) 2 (100) 2 (100) - Friend (total n = 20) 4 (100) 5 (100) 5 (45) a Dementia according to International Classification of Disease 10th Revision (ICD-10) definition. b Cognitive impairment not including dementia (CIND) defined as Petersen mild cognitive impairment or another cause of cognitive impairment such as traumatic brain injury or affective disorder. c Sex was not recorded for 7 participants. d Mean IQCODE scores range 1 to 5, higher scores indicating worse cognition e IQCODE threshold of mean score > 3.3 indicates abnormal test. For example, of the 131 people with dementia, there were 69 who were rated by a spouse informant, and of these 63 (91%) exceeded the abnormal threshold on IQCODE. f AD8 scores range from 0 to 8, higher scores indicate worse cognition. g AD8 threshold of ≥2 indicates abnormal test. h GPCOGi scores range from 0 to 6, lower scores indicate worse cognition. i GPCOGi threshold of < 5 indicates abnormal test. Table 1 also shows that people with dementia had higher mean IQCODE and total AD8 scores (median 4.3 and 7 respectively) than people with CIND (median 3.5 and 4 respectively) and normal cognition (median 3.25 and 2 respectively). People with dementia had lower total scores on GPCOGi (median 1) than people with CIND (median 3) and normal cognition (median 4) Informant Questionnaire Scores by Informant Characteristics Adult descendants tended to score participants more cognitively impaired on all three informant questionnaires when compared to spouses as the baseline informant type. However, there was no difference after adjustment for informant age, participant age, informant sex and diagnosis. Friends tended to score participants less cognitively impaired on all three informant questionnaires when compared to spouses. However, once adjusted for informant age, participant age, informant sex and diagnosis, this difference attenuated for AD8 with modest evidence against the null hypothesis (-1.55, 95% CI -2.74 to -0.36. p = 0.01) and there was no difference for IQCODE and GPCOGi. Siblings did not score participants significantly different on all three informant questionnaires when compared to spouses. (Tables 2 and 3 ). There was no association between informant sex and IQCODE, AD8 or GPCOGi score. With each additional five years in informant age, informants tended to score participants less cognitively impaired on IQCODE and AD8. However, once adjusted for participant age, informant sex and diagnosis, this difference attenuated for IQCODE and there was no difference for AD8. (Tables 2 and 3 ) Table 2 Informant Questionnaire Scores by Informant Characteristics, unadjusted Informant Relationship Type a Spouse Adult descendant Sibling Friend IQCODE - 0.42 (0.25, 0.59) -0.18 (-0.78, 0.42) -0.55 (-0.85, -0.25) AD8 - 1.73 (1.04, 2.43) 0.52 (-1.97, 3.02) -2.48 (-3.66, -1.30) GPCOGi - -0.63 (-1.06, -0.20) -0.24 (-1.80, 1.32) 0.81 (0.07, 1.54) Informant Sex b Female Male IQCODE - 0.09 (-0.10, 0.29) AD8 - -0.03 (-0.82, 0.77) GPCOGi - -0.15 (-0.61, 0.30) Informant Age c Difference in score for every additional five years in informant age IQCODE -0.06 (-0.09, − 0.03) AD8 -0.25 (-0.385, -0.114) GPCOGi 0.04 (-0.04, 0.12) a Difference in score when compared to spouses as the baseline informant type. b Difference in score when compared to male as the baseline informant sex. c Difference in score when compared to normal cognition as the baseline diagnosis. Table 3 Informant Questionnaire Scores by Informant Characteristics, adjusted Informant Relationship Type a Spouse Adult descendant Sibling Friend IQCODE - -0.07 (-0.42, 0.28) -0.35 (-0.88, 0.17) -0.26 (-0.57, 0.05) AD8 - 0.38 (-1.02, 1.78) 0.05 (-2.10, 2.20) -1.55 (-2.74, -0.36) GPCOGi - 0.03 (-0.85, 0.91) 0.09 (-1.26, 1.43) 0.06 (-0.69, 0.80) Informant Sex b Female Male IQCODE - 0.08 (-0.08, 0.24) AD8 - -0.12 (-0.76, 0.53) GPCOGi - -0.10 (-0.50, 0.30) Informant Age Difference in score for every additional five years in informant age IQCODE -0.06 (-0.12, -0.003) AD8 -0.15 (-0.39, 0.10) GPCOGi 0.01 (-0.14, 0.17) Participant Age Difference in score for every additional five years in participant age IQCODE 0.09 (0.01, 0.17) AD8 0.12 (-0.22, 0.45) GPCOGi -0.22 (-0.43, -0.01) Diagnosis c Normal cognition CIND Dementia IQCODE - 0.31 (0.1, 0.53) 0.76 (0.56, 0.96) AD8 - 1.11 (0.25, 1.98) 3.36 (2.55, 4.16) GPCOGi - -0.78 (-1.32, -0.24) -1.84 (-2.34, -1.34) Adjusted for informant type, informant sex, informant age, participant age and diagnosis. a Difference in score when compared to spouses as the baseline informant type. b Difference in score when compared to male as the baseline informant sex. c Difference in score when compared to normal cognition as the baseline diagnosis. Diagnostic accuracy The diagnostic accuracy of IQCODE, AD8 and GPCOGi are summarised in Tables 4 , 5 and 6 respectively. Table 4 Accuracy of informant judgement for the diagnosis of dementia using IQCODE AUROC (95 CI %) Sensitivity (95 CI %) Specificity (95 CI %) PPV (95 CI %) NPV (95 CI %) Overall 0.67 (0.62, 0.72) 95 (90, 98) 38 (29, 48) 67 (60, 74) 86 (73, 95) Informant Relationship Type Spouse 0.62 (0.55, 0.69) 91 (82, 97) 33 (22, 47) 61 (51, 71) 77 (56, 91) Adult descendant 0.63 (0.54, 0.71) 100 (94, 100) 25 (10,47) 76 (64, 85) 100 (54, 100) Sibling 0.75 (0.26, 1) 100 (16, 100) 50 (1, 99) 67 (9, 99) 100 (3, 100) Friend 0.89 (0.78, 1) 100 (40, 100) 79 (49, 95) 57 (18, 90) 100 (72, 100) Informant Sex Male informant 0.74 (0.63, 0.85) 97 (86, 100) 50 (28, 72) 77 (62, 88) 92 (62, 100) Female informant 0.63 (0.57, 0.69) 95 (88, 98) 32 (21, 44) 64 (56, 72) 82 (63, 94) AUROC = areas under the receiver operating characteristic curve. PPV = positive predictive value. NPV = negative predictive value. 95% CI = 95% Confidence interval Table 5 Accuracy of informant judgement for the diagnosis of dementia using AD8 AUROC (95 CI %) Sensitivity (95 CI %) Specificity (95 CI %) PPV (95 CI %) NPV (95 CI %) Overall 0.64 (0.60, 0.69) 97 (92, 99) 32 (23, 42) 64 (56, 70) 90 (75, 97) Informant Relationship Type Spouse 0.61 (0.55, 0.67) 94 (86, 98) 28 (17, 40) 58 (48, 67) 82 (60, 95) Adult descendant 0.56 (0.50, 0.63) 100 (94, 100) 13 (3,32) 73 (61, 82) 100 (30, 100) Sibling 0.7 (0.26, 1) 100 (16, 100) 50 (1, 99) 67 (9, 99) 100 (3, 100) Friend 0.88 (0.77, 0.99) 100 (40, 100) 75 (48, 93) 50 (16, 84) 100 (74, 100) Informant Sex Male informant 0.72 (0.62, 0.82) 100 (91, 100) 44 (24, 65) 73 (58, 84) 100 (72, 100) Female informant 0.60 (0.55, 0.66) 96 (89, 99) 25 (16, 36) 61 (53, 69) 83 (61, 95) AUROC = areas under the receiver operating characteristic curve. PPV = positive predictive value. NPV = negative predictive value 95%. CI 95%. Confidence interval Table 6 Accuracy of informant judgement for the diagnosis of dementia using GPCOGi AUROC (95 CI %) Sensitivity (95 CI %) Specificity (95 CI %) PPV (95 CI %) NPV (95 CI %) Overall 0.59 (0.56, 0.63) 99 (96, 100) 20 (13, 28) 60 (53, 67) 96 (77, 100) Informant Relationship Type Spouse 0.58 (0.53, 0.63) 99 (92, 100) 17 (9, 28) 56 (47, 65) 92 (62, 100) Adult descendant 0.58 (0.51, 0.66) 100 (94, 100) 17 (5, 37) 74 (62, 83) 100 (40, 100) Sibling a - - - - - Friend 0.69 (0.57, 0.81) 100 (40, 100) 38 (15, 64) 29 (8, 58) 100 (54, 100) Informant Sex Male informant 0.62 (0.54, 0.71) 100 (91, 100) 24 (9, 45) 66 (52, 54) 100 (54, 100) Female informant 0.57 (0.53, 0.62) 99 (94, 100) 16 (8, 26) 59 (51, 67) 92 (64, 100) AUROC = areas under the receiver operating characteristic curve. PPV = positive predictive value. NPV = negative predictive value 95%. CI 95% = Confidence interval a All four informants classed as siblings categorised patient participants as impaired on GPCOGi All informants Overall sensitivity was 95% (95% CI 90–98%) for IQCODE, 97% (95% CI 92–99%) for AD8 and 99% (95% CI 96–100%) for GCPOGi. Overall specificity was 38% (95% CI 29–48%) for IQCODE, 32% (95% CI 23–42%) for AD8 and 20% (95% CI 13–28%) for GPCOGi. Overall accuracy was similar for all informant questionnaires with area under the receiver operating characteristic curve (AUROC) of 0.67 (95% CI, 0.62 to 0.72) for IQCODE, 0.64 (95% CI, 0.60 to 0.69) for AD8 and 0.59 (95% CI, 0.56 to 0.63) for GPCOGi, though the 95% confidence intervals only just overlapped for IQCODE and GPCOGi. Informants by Relationship Type Sensitivity was consistently high across all informant relationship types for all three informant questionnaires. Sensitivity by informant relationship type ranged from 91–100% for IQCODE, 94–100% for AD8 and 99% to100% for GPCOGI. Spouses tended to have the lowest sensitivity. However, sensitivity CIs overlap across all informant types on IQCODE, AD8 and GPCOGi and these differences were consistent with chance. Specificity was lower across all informant relationship types for all three informant questionnaires. Specificity by informant relationship type ranged from 25–79% for IQCODE, 13–75% for AD8 and 17–38% for GPCOGi. Adult descendants tended to have the lowest specificity at 25% (95% CI 10–47%) for IQCODE, 13% (95% CI 3–32%) for AD8 and 17% (95% CI 5–37%) for GPCOGi. Friends tended to have the highest specificity at 79% (95% CI 49–95%) for IQCODE, 75% (95% CI 48–93%) for AD8 and 38% (95% CI 15–64%) for GPCOGi. AUROC by informant relationship type ranged from 0.62 to 0.89 for IQCODE, 0.56 to 0.88 for AD8 and 0.58 to 0.69 for GPCOGi. Friends tended to have the highest AUROC at 0.89 (95% CI 0.78 to 1) for IQCODE, 0.88 (95% CI 0.77 to 0.99) for AD8 and 0.69 (95% CI 0.57 to 0.81) for GPCOGi. It was not possible to calculate a p value for GPCOGi because there were zero siblings who rated their participant as being cognitively healthy. However, there was strong evidence against the null hypothesis of no difference by informant type for IQCODE (p = 0.0004) and AD8 (p = 0.0001), suggesting that overall friends are more accurate when using IQCODE and AD8, due to an increase in the specificity (that is, ability to detect correctly someone without dementia), without loss of sensitivity. There was substantial uncertainty in the estimates for friends and siblings with large confidence intervals, as there were small numbers of these informants. Informants by Sex Females had a higher AUROC for all three tests, driven by higher specificity for females. However, 95% CIs overlapped and were consistent with chance. Missing IQCODE scores We found no association between informant sex and missing IQCODE. The odds ratio for not completing IQCODE was 2.1 (95% 0.46 to 9.6, p = 0.35) when male informants were compared to female informants. We did find an association between missing IQCODE and informant age. The seven informants who did not complete IQCODE were on average 12 years older (95% CI 2 years to 21 years) than those who did complete the IQCODE; t test p = 0.02. Discussion This is the first study to our knowledge to explore diagnostic accuracy by informant relationship type. Overall, all three informant tests had relatively high sensitivity, low specificity and had a similar AUROC. Compared to spouses, adult descendants tended to score participants more cognitively impaired, whereas friends scored participants less cognitively impaired on all three questionnaires. However, there was little evidence of scoring difference by informant relationship type once fully adjusted, except for friends who scored participants lower on AD8. Friends tended to have the best overall diagnostic accuracy with the highest AUROC for IQCODE, AD8 and GPCOGi. Comparison with existing literature Although common thresholds for detecting dementia using IQCODE tend to be applied (often ranging from 3.3 to 3.6), there is no universally accepted threshold, making comparison across studies challenging [ 18 ]. Previous literature, which considers studies with varying thresholds, suggests a pooled estimate of IQCODE sensitivity of 80–91% and specificity of 65–85% but study quality is noted to be poor [ 11 ]. A systematic review found only one previous suitable study conducted in primary care [ 19 ]. The identified study had a sensitivity of 100% and specificity of 82% using a threshold of 3.3. The study reported a decreasing sensitivity and increasing specificity as the threshold increased and suggested an optimal cut-point of 3.35 using AUROC analyses [ 20 ]. We found a similarly high sensitivity but a notably lower specificity in comparison to that study which may reflect aspects of the study design. For example, the other study conducted IQCODE over the telephone, had a lower prevalence of dementia (7% compared to 54% in our study), had a similar proportion of informants that were a spouse (47%), and was assessed as being at high risk of bias in all four Quality Assessment of Diagnostic Accuracy Studies (QUADAS) domains [ 19 , 20 ]. The original author for AD8 defined a threshold of 2 [ 9 ]. However, systematic reviews identified that thresholds applied in studies have differed and result in differing test performance [ 21 , 22 ]. For example, a systematic review looking at the use of AD8 across healthcare settings found a sensitivity of 92% and specificity of 64% at a threshold of ≥ 2 compared to a sensitivity of 91% and specificity of 76% at a threshold of ≥ 3 [ 22 ]. The systematic review identified only one study in a primary care setting which reported a sensitivity of 90% and specificity of 88% using a threshold of ≥ 3 [ 23 ]. We found a similar sensitivity of 97%, but lower specificity of 32% using a threshold of ≥ 2. The other study in primary care was assessed as being at risk of bias in one QUADAS domain and unclear in two [ 22 ]. There is less data available to evaluate the use of GPCOG. The original study reported a sensitivity of 85% and specificity of 86% when used as the full two-stage questionnaire. The informant component used in isolation had a reported sensitivity of 89% and specificity of 66% [ 10 ]. We found higher sensitivity, 99%, and a notably lower specificity, 20%, in comparison to the original study which may reflect aspects of the study design. We only included those over age 70 where a concern about cognition had been raised and there was no formal diagnosis of dementia. However, the original GPCOG study included all adults over 75 regardless of cognitive status and those aged 50 to 74 with suspected cognitive impairment [ 10 ]. All informants completed AD8 and GPCOG. This is consistent with their reported ease of administration including fast completion and minimal training requirements [ 10 , 21 ]. Not all informants completed IQCODE in this study, but completion was still high at 97%. An in-hospital study found poor uptake and completion rate of IQCODE by informants. It is likely that this reflected the inpatient nature of the study, and the authors suggested that short admissions and relatives being away from the ward during working hours may have been contributing factors [ 24 ]. Conversely, a community study suggested IQCODE was acceptable to informants and easy to use, which is in keeping with our findings [ 25 ]. Informant characteristics may influence test scores. However, reported data on the influence of informant characteristics is limited and variable. One study reported that the age of informants who were wives was not associated with IQCODE scoring [ 12 , 13 ]. When considering all informant types, we found older informants scored participants less cognitively impaired on IQCODE. We found no association between AD8 or GPCOGi score and informant age when adjusted for informant sex and informant type. Some investigators have reported that IQCODE is not influenced by relationship type or length [ 13 ], whereas others have found that spouses reported better cognitive function for patients than non-spouses [ 26 ]. We found that friends, compared to spouses, tended to score participants less cognitively impaired on IQCODE and also AD8. Strengths and limitations We recruited a representative group of participants from several GP surgeries, across a geographically diverse area. Our findings are therefore likely to closely reflect clinical practice in the United Kingdom. Although we made efforts to maximise inclusion, including providing translation services, participants were mostly white, native English speakers. IQCODE is, however, thought to be relatively unaffected by language and AD8 has been translated and validated in a variety of languages [ 18 , 22 ]. This study has limited applicability to people with advanced cognitive impairment, since we excluded those people. The uncertainty in the estimates increases when analysing by informant subtype, which limits the extent to which we can draw comparisons between categories; the number of informants in the sibling category was especially small, with large confidence intervals. Whilst we would expect informants attending the research clinic to mirror similar patterns to those who may routinely accompany patients to appointments, we could not investigate this formally. Index test informant measures (IQCODE, AD8, GPCOGi) were not used by the expert assessors when deciding the reference standard diagnosis, but the same informant who completed these index tests contributed to the expert evaluation and completed BADL, though this formed only one part of the holistic expert judgement about the diagnosis. We applied a commonly used threshold for IQCODE and AD8, but there are a range of thresholds [ 18 , 21 , 22 ]. The accuracy at other thresholds may be different. An alternative approach for primary care could be to apply a threshold which optimises for specificity and therefore the use of informant questionnaires to rule in dementia, minimising overdiagnosis and associated psychological harm. However, further analysis exploring the influence of threshold by informant relationship type would be required. GPCOG consists of two components, a patient and informant questionnaire but we evaluated the informant component of GPCOG in isolation because we were interested specifically in informant characteristics [ 10 ]. Conclusion Overall, informants, of any relationship type, when using IQCODE, AD8 or GPCOGi may be useful for ruling out dementia but not for ruling it in. We found little difference between spouse and adult descendants, who made around 90% of informants. In contrast only 8% of informants were a friend, but they performed significantly better overall on IQCODE and AD8 due to an increase in specificity without loss of sensitivity. AD8 and GPCOGi have fewer items than IQCODE and are arguably less time-consuming in a traditional consultation. However, with the increasing use of e-consultations, this may be less of a consideration as informant questionnaires could be sent electronically, or posted, prior to an appointment. If an informant questionnaire does not suggest impaired cognition, this could guide the consultation to consider alternative causes for the presentation such as hearing or visual impairment or mood disorders. Indeed, one option in people over 70 years, who do not report otherwise seriously distressing symptoms, would be to use a normal IQCODE, AD8 or GPCOGi to avoid prolonged and burdensome diagnostic pathways for patients and carers, recognising that if patients or their family desired further tests then clinicians could (perhaps should) offer these. Future research should examine how informants rating of cognition might change over time and whether this differs by type of informant. Where IQCODE, AD8 or GPCOGi scoring is suggestive of dementia, we believe clinicians should use a further tool with high specificity to avoid misdiagnosis. In our related paper from the same study, we found that GP judgement was highly specific but poorly sensitive [ 15 ]. Given the low burden of both GP judgement and informant questionnaires, a further area of research would be to consider whether combining both these tools could achieve reasonable diagnostic accuracy in general practice. Informants provide invaluable information in helping assess the clinical diagnosis of dementia. We find little empirical evidence that the type of informant is important in ruling out a diagnosis but may differ if trying to rule in a diagnosis. Abbreviations ACE-III: Addenbrooke’s Cognitive Examination III AUROC: Area under receiver operator curve BADL: Bristol Activities of Daily Living BASDEC: Brief Assessment Schedule Depression Cards BNSSG: Bristol, North Somerset and South Gloucestershire CIND: Cognitive impairment not dementia GP: General Practitioner/Practice GPCOG: General Practitioner Assessment of Cognition GPCOGi: informant component of General Practitioner Assessment of Cognition ICD-10: International Classification of Disease 10th Revision IQCODE: Informant Questionnaire on Cognitive Decline in the Elderly NICE: National Institute for Health and Care Excellence Declarations Ethnics approval and consent to participate The National Research Ethics Service Committee London – Bromley (reference 14/LO/2025) gave a favourable ethical opinion on 25 November 2014. NHS Research and Development approvals were granted by Avon Primary Care Research Collaboration on behalf of Bristol, North Somerset and South Gloucestershire clinical commissioning groups. The University of Bristol acted as Sponsor. Consent for publication Not applicable. Availability of data and materials The datasets used and analysed during the current study are available from the corresponding author on reasonable request. Competing interests The authors declare no competing interest. Funding The research reported in this publication was funded through The Wellcome Trust (Fellowship 108804/Z/15/z), Avon Primary Care Research Collaboration, The Claire Wand fund, and the National Institute for Health Research School for Primary Care Research. The Western Clinical Research Networks approved an application for service support costs for practices to provide for the expense of room hire in GP surgeries and GPs referring people to the study. Author contributions JC and STC prepared the main manuscript including data analysis, interpretation and preparation of all tables and figures. All authors contributed to conception of the research question and review of the manuscript. Acknowledgements The authors thank the participants and the staff at participating practices, without whom this work would not have been possible. The staff at the West of England Clinical Research Network arranged for redaction, collection, and transport of medical records from general practices. References National Institute for Health and Care Excellence. Dementia: What is it? https://cks.nice.org.uk/topics/dementia/backgroun d-information/definition/. Accessed 5 June 2024. Alzheimer's Society. Alzheimer’s Society’s view on diagnosis and assessment. https://www.alzheimers.org.uk/about-us/policy-and-influencing/what-we-think/diagnosis-assessment. Accessed 5 June 2024. Manthorpe J, Samsi K, Campbell S, Abley C, Keady J, Bond J, et al. From forgetfulness to dementia: clinical and commissioning implications of diagnostic experiences. British Journal of General Practice. 2013;63:e69–75. Wittenberg R, Hu B, Barraza-Araiza LF, Rehill A. Projections of Older People with Dementia and Costs of Dementia Care in the United Kingdom, 2019-2040. CPEC Working Paper 5. 2019; November:1–79. NHS England. Dementia. https://www.england.nhs.uk/mental-health/dementia/. Accessed 5 June 2024. National Institute for Health and Care Excellence. Dementia: assessment, management and support for people living with dementia and their carers. NICE Guideline (NG97). https://www.nice.org.uk/guidance/ng97/chapter/Recommendations#diagnosis. Accessed 5 June 2024. James Lind Alliance. Dementia Top 10 | https://www.jla.nihr.ac.uk/priority-setting-partnerships/dementia/top-10-priorities/. Accessed 5 June 2024. Jorm AF. A short form of the Informant Questionnaire on Cognitive Decline in the Elderly (IQCODE): development and cross-validation. Psychol Med. 1994;24:145–53. Galvin JE, Roe CM, Powlishta KK, Coats MA, Muich SJ, Grant E, et al. The AD8: brief informant interview to detect dementia. Neurology. 2005;65:559–64. Brodaty H, Pond D, Kemp NM, Luscombe G, Harding L, Berman K, et al. The GPCOG: A New Screening Test for Dementia Designed for General Practice. J Am Geriatr Soc. 2002;50:530–4. Taylor-Rowan M, Nafisi S, Owen R, Duffy R, Patel A, Burton JK, et al. Informant-based screening tools for dementia: an overview of systematic reviews. Psychol Med. 2023;53:580-9. Jorm AF, Broe GA, Creasey H, Sulway MR, Dent O, Fairley MJ, et al. Further data on the validity of the informant questionnaire on cognitive decline in the elderly (IQCODE). Int J Geriatr Psychiatry. 1996;11:131-9. Fuh JL, Teng EL, Lin KN, Larson EB, Wang SJ, Liu CY, et al. The Informant Questionnaire on Cognitive Decline in the Elderly (IQCODE) as a screening tool for dementia for a predominantly illiterate Chinese population. Neurology. 1995;45:92–6. Office for National Statistics. Health geographies population estimates (Accredited official statistics). https://www.ons.gov.uk/peoplepopulationandcommunity/populationandmigration/populationestimates/datasets/clinicalcommissioninggroupmidyearpopulationestimates. Accessed 5 June 2024. Creavin ST, Haworth J, Fish M, Cullum S, Bayer A, Purdy S, et al. Clinical judgment of GPs for the diagnosis of dementia: a diagnostic test accuracy study. BJGP Open. 2021; 5(5):BJGPO.2021.0058. ICD-10 Version:2019. https://icd.who.int/browse10/2019/en#/F00-F09. Accessed 5 June 2024. Petersen RC. Mild cognitive impairment as a diagnostic entity. J Intern Med. 2004;256:183–94. Jorm AF. The Informant Questionnaire on Cognitive Decline in the Elderly (IQCODE): a review. Int Psychogeriatr. 2004;16:275–93. Harrison JK, Fearon P, Noel-Storr AH, McShane R, Stott DJ, Quinn TJ. Informant Questionnaire on Cognitive Decline in the Elderly (IQCODE) for the diagnosis of dementia within a general practice (primary care) setting. Cochrane Database of Systematic Reviews. 2014;7:CD010771. Tokuhara KG, Valcour VG, Masaki KH, Blanchette PL. Utility of the Informant Questionnaire on Cognitive Decline in the Elderly (IQCODE) for dementia in a Japanese-American population. Hawaii Med J. 2006;65:72–5. Chen HH, Sun FJ, Yeh TL, Liu HE, Huang HL, Kuo BIT, et al. The diagnostic accuracy of the Ascertain Dementia 8 questionnaire for detecting cognitive impairment in primary care in the community, clinics and hospitals: a systematic review and meta-analysis. Fam Pract. 2018;35:239-46. Hendry K, Green C, McShane R, Noel-Storr AH, Stott DJ, Anwer S, et al. AD‐8 for detection of dementia across a variety of healthcare settings. Cochrane Database Syst Rev. 2019;3:CD011121. Chan QL, Xu X, Shaik MA, Chong SST, Hui RJY, Chen CLH, et al. Clinical Utility of the Informant AD8 as a Dementia Case Finding Instrument in Primary Healthcare. JAlzheimers Dis. 2016;49:121–7. Bloomfield K, John N. Informant Questionnaire on Cognitive Decline in the Elderly (IQCODE) completion on an acute care ward for the elderly: a brief study of informant characteristics. Int Psychogeriatr. 2012;24:1700–1. Hancock P, Larner AJ. Diagnostic utility of the Informant Questionnaire on Cognitive Decline in the Elderly (IQCODE) and its combination with the Addenbrooke’s Cognitive Examination-Revised (ACE-R) in a memory clinic-based population. Int Psychogeriatr. 2009;21:526–30. Nygaard HA, Naik M, Geitung JT. The Informant Questionnaire on Cognitive Decline in the Elderly (IQCODE) is associated with informant stress. Int J Geriatr Psychiatry. 2009;24:1185–91. Additional Declarations No competing interests reported. Cite Share Download PDF Status: Published Journal Publication published 15 Apr, 2025 Read the published version in BMC Primary Care → Version 1 posted Editorial decision: Revision requested 28 Jun, 2024 Editor assigned by journal 26 Jun, 2024 Submission checks completed at journal 26 Jun, 2024 First submitted to journal 25 Jun, 2024 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-4637777","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":320192117,"identity":"0466a6a5-7937-422c-aa1d-ec43243f85ce","order_by":0,"name":"Jasmine Chingono","email":"data:image/png;base64,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","orcid":"","institution":"University of Bristol","correspondingAuthor":true,"prefix":"","firstName":"Jasmine","middleName":"","lastName":"Chingono","suffix":""},{"id":320192118,"identity":"bca826e4-6243-4787-a9ee-a9a8c1964f75","order_by":1,"name":"Samuel Thomas Creavin","email":"","orcid":"","institution":"University of Bristol","correspondingAuthor":false,"prefix":"","firstName":"Samuel","middleName":"Thomas","lastName":"Creavin","suffix":""},{"id":320192119,"identity":"2072eb37-60e3-4a7a-98ec-c893b1084e60","order_by":2,"name":"Mark Fish","email":"","orcid":"","institution":"Royal Devon \u0026 Exeter NHS Foundation Trust","correspondingAuthor":false,"prefix":"","firstName":"Mark","middleName":"","lastName":"Fish","suffix":""},{"id":320192120,"identity":"92e85642-8279-4c2c-8c2b-1387ccfbf7f0","order_by":3,"name":"Sarah Cullum","email":"","orcid":"","institution":"The University of Auckland","correspondingAuthor":false,"prefix":"","firstName":"Sarah","middleName":"","lastName":"Cullum","suffix":""},{"id":320192121,"identity":"31552dec-4926-4112-b0cb-01ba0c54e78d","order_by":4,"name":"Antony Bayer","email":"","orcid":"","institution":"Cardiff University","correspondingAuthor":false,"prefix":"","firstName":"Antony","middleName":"","lastName":"Bayer","suffix":""},{"id":320192122,"identity":"f8f88c9b-dac0-4e3b-9a7f-3a7bbdb15358","order_by":5,"name":"Sarah Purdy","email":"","orcid":"","institution":"University of Bristol","correspondingAuthor":false,"prefix":"","firstName":"Sarah","middleName":"","lastName":"Purdy","suffix":""},{"id":320192123,"identity":"aaba4780-4364-41bd-8116-b2cfb2d947d3","order_by":6,"name":"Yoav Ben-Shlomo","email":"","orcid":"","institution":"University of Bristol","correspondingAuthor":false,"prefix":"","firstName":"Yoav","middleName":"","lastName":"Ben-Shlomo","suffix":""}],"badges":[],"createdAt":"2024-06-25 16:11:29","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-4637777/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-4637777/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1186/s12875-025-02745-w","type":"published","date":"2025-04-15T15:57:11+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":60705970,"identity":"82a822d4-94c8-4c32-b155-41122ac4e3ed","added_by":"auto","created_at":"2024-07-19 19:24:00","extension":"jpg","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":74548,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eSTARDem flowchart for study inclusion of participants\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003csup\u003e\u003cem\u003e†\u003c/em\u003e\u003c/sup\u003e One person withdrew as acutely unwell\u003c/p\u003e\n\u003cp\u003e\u003csup\u003e§\u003c/sup\u003eIQCODE was offered to all informants. Seven declined.\u003c/p\u003e\n\u003cp\u003e\u003csup\u003e#\u003c/sup\u003eDementia according to International Classification of Disease 10\u003csup\u003eth\u003c/sup\u003e Revision (ICD-10) definition.\u003c/p\u003e\n\u003cp\u003e*Cognitive impairment not including dementia (CIND) defined as Petersen mild cognitive impairment or another cause of cognitive impairment such as traumatic brain injury or affective disorder\u003c/p\u003e","description":"","filename":"1.jpg","url":"https://assets-eu.researchsquare.com/files/rs-4637777/v1/185276753d6d1fcb9b15d22b.jpg"},{"id":81050778,"identity":"ad55c4d1-7830-469c-aff5-b40edca721df","added_by":"auto","created_at":"2025-04-21 16:04:40","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1288585,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-4637777/v1/d30c324d-0dc7-4016-ad56-fa53557d4255.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Informant Accuracy of IQCODE, AD8 and GPCOGi for diagnosis of dementia: Does your friend know best?","fulltext":[{"header":"Introduction","content":"\u003cp\u003eDementia is a syndrome of progressive, cognitive symptoms including memory disturbance, difficulties with language, executive function, visuospatial skills and changes in behaviour [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]. Timely and accurate diagnosis allows patients and their carers to access appropriate medication, services and engage in advanced care planning [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]. However, the path to a dementia diagnosis can be lengthy, with patients and their carers experiencing considerable uncertainty and a lack of patient-centredness [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eMany people living with cognitive problems do not have a formal diagnosis of dementia, and pressure on diagnostic pathways is anticipated to increase in future [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e, \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]. In the United Kingdom, a dementia diagnosis can require referral to a specialist dementia diagnostic service, and the role of primary care in supporting a more effective pathway to diagnosis is a priority research area [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e, \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eAn informant is a person close to a patient, such as a family member, friend, or caregiver, who can provide additional information to aid diagnosis. The use of a structured informant questionnaire is advocated by the National Institute for Health and Care Excellence (NICE) as part of an initial assessment [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]. Examples include the Informant Questionnaire on Cognitive Decline in the Elderly (IQCODE), AD8 and General Practitioner Assessment of Cognition (GPCOG) [\u003cspan additionalcitationids=\"CR9\" citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e–\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]. GPCOG, designed for use in a primary care setting, consists of two parts and includes a component for the informant to complete (GPCOGi) [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]. All three informant questionnaires ask the informant to rate the patient’s performance on several cognitive indicators compared to several years ago.\u003c/p\u003e \u003cp\u003eA recent overview of informant questionnaires for dementia concluded there is currently only sufficient evidence to justify the use of IQCODE and AD8. However, it also highlighted that there is little evidence available for their use in primary care settings despite test performance varying by setting and primary care being an important setting for identifying cognitive impairment [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eInformant characteristics may affect scoring and therefore accuracy of informant tests. For example, a study found that wives with more anxiety or depressive symptoms tended to rate more cognitive impairment in their husbands on the IQCODE [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]. However, previous studies suggest that IQCODE scores are not influenced by length or type of relationship, age, or educational status of the informant [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e, \u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]. These studies examined associations between tests scores and relationship types, rather than test accuracy, which is more clinically relevant.\u003c/p\u003e \u003cp\u003eThe aim of this study was therefore to address these research gaps by exploring the diagnostic accuracy of IQCODE, AD8 and GPCOGi in a primary care setting, and whether this differed by informant characteristics, particularly relationship type.\u003c/p\u003e "},{"header":"Methods","content":"\u003cp\u003eThis was a prospective diagnostic accuracy study.\u003c/p\u003e\u003cp\u003ePopulation\u003c/p\u003e\u003cp\u003eWe recruited participants between March 2015 and May 2017 from 21 general practitioner (GP) surgeries in the Bristol, North Somerset and South Gloucestershire (BNSSG) area in the South West of England. This covered a diverse area around the city of Bristol, with a total population of around 900,000, with 12% aged over 70 [\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eInclusion and Exclusion Criteria\u003c/p\u003e\u003cp\u003eWe included people aged over 70 years who were seeking evaluation for concerns about cognition but did not have an existing formal diagnosis of dementia. We did not specify the nature or severity of the cognitive symptoms, but these must have been present for at least six months, and reported by the person themselves, someone close to them or a healthcare professional. We required that an informant attended the research clinic as a criterion for participation, to enable robust diagnosis.\u003c/p\u003e\u003cp\u003eWe excluded people with a known neurological disorder (including Parkinsonism, multiple sclerosis, learning disability, and Huntington’s disease), a psychiatric disorder requiring secondary care input, those registered blind, profound deafness preventing the use of a telephone, those with rapidly progressive symptoms and those with advanced cognitive problems unable to consent.\u003c/p\u003e\u003cp\u003eWe encouraged GPs to refer all consecutive eligible patients regardless of their clinical judgement or any initial test results. Further details have been reported previously [\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eIndex test\u003c/p\u003e\u003cp\u003eWe asked informants to complete the IQCODE-16, GPCOGi, and AD8 during the research clinic visit, facilitated by a single GP and performed as outlined by the original authors [\u003cspan additionalcitationids=\"CR9\" citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e–\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]. The facilitating GP was not aware of any other clinical information related to the participant or informant.\u003c/p\u003e\u003cp\u003eThe IQCODE-16 asks the informant to rate the patient from 1: “much improved” to 5: “much worse” now, compared to 10 years ago, across 16 questions and a mean score calculated. The original version of IQCODE consisted of 26 items. A short form, consisting of 16 items was subsequently developed and found to have comparable validity [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eAD8 consists of eight questions assessing whether for each statement there has been a change in the last several years caused by cognitive problems. Response options are: “yes, a change”, “no, no change” or “N/A, don’t know”. Answers “yes, a change” score 1 and other responses do not score. The AD8 can be completed by a patient or informant [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eUnlike IQCODE and AD8, GPCOG includes both a patient and informant component. The informant component consists of six questions asking the informant to compare the patient to how they were a few years ago. Response options are “yes”, “no”, “don’t know”, “N/A”. All responses except “yes” score 1 point [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]. Only the informant scores were used for analysis in this study. We refer to this as GPCOGi.\u003c/p\u003e\u003cp\u003eWe used a threshold of \u0026gt; 3.3 as a threshold for an abnormal index test on IQCODE (mean scores range 1–5; higher scores indicating worse cognition). This reflected the threshold used for the pooled analysis in Cochrane systematic review [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]. A threshold of greater or equal to 2 on AD8 (scores range 0–8; higher scores indicating worse cognition ) and \u0026lt; 5 on the GPCOGi (max score 6, lower scores indicating worse cognition).\u003c/p\u003e\u003cp\u003eWe categorised informant relationship types as spouse, adult descendant, sibling or friend, and collected information on informant age and sex, all based on self-report.\u003c/p\u003e\u003cp\u003eReference standard\u003c/p\u003e\u003cp\u003eA single specialist physician assessed participants over approximately one hour using a clinical history, Addenbrooke’s Cognitive Examination III (ACE-III), Brief Assessment Schedule Depression Cards (BASDEC) and the informant-completed Bristol Activities of Daily Living (BADL) Questionnaire. The specialist physician did not use specific thresholds for these measures and was not aware of any GP judgement, other test results or investigations. The specialist used their integrated assessment to consider a dementia diagnosis according to ICD-10 criteria [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]. The same specialist physician could also assign a diagnosis of Cognitive Impairment Not Dementia (CIND) if they felt their assessment met the criteria for Petersen mild cognitive impairment, or another cause of cognitive impairment such as traumatic brain injury or affective disorder [\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e]. We reviewed medical records for all patient participants six months after the research clinic to find subsequent information that would contradict the initial research clinic judgement. For borderline cases a second independent specialist reviewed initial assessment as well as the medical record to determine a final diagnostic classification.\u003c/p\u003e\u003cp\u003eStatistical methods\u003c/p\u003e\u003cp\u003eWe summarised information on participants and the variation across cognitive categories and informant types. We used linear regression to test the hypothesis of no association between continuous informant test score and categorical informant type (adult descendant, sibling, friend), compared to spouse as the baseline category. We derived diagnostic accuracy parameters with 95% confidence intervals for informant tests at pre-specified thresholds (see Index Tests) compared to reference standard dementia as determined by specialist assessment. We calculated sensitivity and specificity of informant tests at these thresholds in subgroups to derive accuracy by informant type and sex. We used logistic regression and t tests to investigate potential associations between a missing informant score and informant relationship type, age, and sex. We used Stata 15 for analysis.\u003c/p\u003e"},{"header":"Results","content":"\u003cp\u003eParticipants\u003c/p\u003e \u003cp\u003e We recruited 240 participants. Figure\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e shows a flowchart of study inclusion. We had demographic information available for 238 informants, and of these 231 completed IQCODE, and 238 completed AD8 and GPCOGi. The specialist classified all 240 patient participants according to the reference standard: \u0026lsquo;dementia\u0026rsquo; (n\u0026thinsp;=\u0026thinsp;132), \u0026lsquo;CIND\u0026rsquo; (n\u0026thinsp;=\u0026thinsp;61) and \u0026lsquo;normal\u0026rsquo; cognition (n\u0026thinsp;=\u0026thinsp;47). For the 238 who also had informant information, the specialist classified the patient-participants as: \u0026lsquo;dementia\u0026rsquo; (n\u0026thinsp;=\u0026thinsp;131), \u0026lsquo;CIND\u0026rsquo; (n\u0026thinsp;=\u0026thinsp;60) and \u0026lsquo;normal\u0026rsquo; cognition (n\u0026thinsp;=\u0026thinsp;47).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eTable\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e summarises informant characteristics and informant questionnaire score by participant cognitive category according to the reference standard.\u003c/p\u003e \u003cp\u003eThe median informant age was 70 years (IQR 60 years to 78 years). Informants for people with dementia tended to be younger (median age 69 years) than informants for people with normal cognition (median age 71 years) or with CIND (median age 73 years). Most informants were women (71%), and this was similar for patients categorised as having dementia, CIND or being cognitively normal.\u003c/p\u003e \u003cp\u003eThe most common informant type overall was spouse, 56% (n\u0026thinsp;=\u0026thinsp;134). People with dementia were more often accompanied by an adult descendant (43%) than people with CIND (28%) or normal cognition (15%), OR 4.3 (95% CI 1.7 to 11; p\u0026thinsp;=\u0026thinsp;0.0006).\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eCharacteristics of informants by patient participant cognitive category\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"4\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colspan=\"3\" nameend=\"c4\" namest=\"c2\"\u003e \u003cp\u003eCognitive category\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eInformant Characteristic\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cb\u003eDementia\u003c/b\u003e\u003csup\u003e\u003cb\u003ea\u003c/b\u003e\u003c/sup\u003e\u003c/p\u003e \u003cp\u003e(n\u0026thinsp;=\u0026thinsp;131)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u003cb\u003eCIND\u003c/b\u003e\u003csup\u003e\u003cb\u003eb\u003c/b\u003e\u003c/sup\u003e\u003c/p\u003e \u003cp\u003e(n\u0026thinsp;=\u0026thinsp;60)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cb\u003eNormal cognition\u003c/b\u003e\u003c/p\u003e \u003cp\u003e(n\u0026thinsp;=\u0026thinsp;47)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMedian age of informant at clinic, years (IQR)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e69 (59\u0026ndash;78)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e73 (58\u0026ndash;77)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e71 (65\u0026ndash;77)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSex (column %)\u003csup\u003ec\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMale n\u0026thinsp;=\u0026thinsp;62 (26)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e37 (28)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e13 (22)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e12 (26)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eFemale n\u0026thinsp;=\u0026thinsp;169 (71)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e93 (71)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e46 (77)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e30 (64)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eInformant type, n (column %)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSpouse n\u0026thinsp;=\u0026thinsp;134 (56)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e69 (53)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e36 (60)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e29 (62)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAdult descendant n\u0026thinsp;=\u0026thinsp;80 (34)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e56 (43)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e17 (28)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e7 (15)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSibling n\u0026thinsp;=\u0026thinsp;4 (2)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e2 (2)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e2 (3)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0 (0)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eFriend n\u0026thinsp;=\u0026thinsp;20 (8)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e4 (3)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e5 (8)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e11 (23)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"4\" nameend=\"c4\" namest=\"c1\"\u003e \u003cp\u003e\u003cb\u003eIQCODE\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMean IQCODE median score\u003csup\u003ed\u003c/sup\u003e (IQR)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e4.3 (3.8\u0026ndash;4.6)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e3.5 (3.3\u0026ndash;4.1)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e3.25 (3.1 to 3.4)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"4\" nameend=\"c4\" namest=\"c1\"\u003e \u003cp\u003e\u003cem\u003ePeople in each cognitive category whose score exceeded the abnormal IQCODE threshold, for each informant type, n (%)\u003c/em\u003e\u003csup\u003e\u003cem\u003ee\u003c/em\u003e\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSpouse (total n\u0026thinsp;=\u0026thinsp;129)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e63 (91)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e25 (78)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e15 (54)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAdult descendant (total n\u0026thinsp;=\u0026thinsp;80)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e56 (100)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e13 (76)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e5 (71)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSibling (total n\u0026thinsp;=\u0026thinsp;4)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e2 (100)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1 (50)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0 (0)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eFriend (total n\u0026thinsp;=\u0026thinsp;18)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e4 (100)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e2 (50)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e1 (10)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"4\" nameend=\"c4\" namest=\"c1\"\u003e \u003cp\u003e\u003cb\u003eAD8\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAD8 median score\u003csup\u003ef\u003c/sup\u003e (IQR)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e7 (5\u0026ndash;8)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e4 (2\u0026ndash;6)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e2 (0\u0026ndash;3)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"4\" nameend=\"c4\" namest=\"c1\"\u003e \u003cp\u003e\u003cem\u003ePeople in each cognitive category whose score exceeded the abnormal AD8 threshold, for each informant type, n (%)\u003c/em\u003e\u003csup\u003e\u003cem\u003eg\u003c/em\u003e\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSpouse (total n\u0026thinsp;=\u0026thinsp;134)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e65 (94)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e26 (72)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e21 (72)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAdult descendant (total n\u0026thinsp;=\u0026thinsp;80)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e56 (100)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e16 (94)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e5 (71)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSibling (total n\u0026thinsp;=\u0026thinsp;4)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e2 (100)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1 (50)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eFriend (total n\u0026thinsp;=\u0026thinsp;20)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e4 (100)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e2 (40)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e2 (18)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"4\" nameend=\"c4\" namest=\"c1\"\u003e \u003cp\u003e\u003cb\u003eGPCOGi\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eGPCOGi total median score\u003csup\u003eh\u003c/sup\u003e (IQR)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1 (1\u0026ndash;3)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e3 (2\u0026ndash;4)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e4 (3\u0026ndash;5)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"4\" nameend=\"c4\" namest=\"c1\"\u003e \u003cp\u003e\u003cem\u003ePeople in each cognitive category whose score exceeded the abnormal GPCOGi threshold, for each informant type, n (%)\u003c/em\u003e\u003csup\u003e\u003cem\u003ei\u003c/em\u003e\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSpouse (total n\u0026thinsp;=\u0026thinsp;134)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e68 (99)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e32 (89)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e22 (76)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAdult descendant (total n\u0026thinsp;=\u0026thinsp;80)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e56 (100)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e15 (88)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e5 (71)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSibling (total n\u0026thinsp;=\u0026thinsp;4)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e2 (100)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e2 (100)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eFriend (total n\u0026thinsp;=\u0026thinsp;20)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e4 (100)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e5 (100)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e5 (45)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"4\" nameend=\"c4\" namest=\"c1\"\u003e \u003cp\u003e\u003csup\u003ea\u003c/sup\u003e Dementia according to International Classification of Disease 10th Revision (ICD-10) definition. \u003csup\u003eb\u003c/sup\u003eCognitive impairment not including dementia (CIND) defined as Petersen mild cognitive impairment or another cause of cognitive impairment such as traumatic brain injury or affective disorder. \u003csup\u003ec\u003c/sup\u003e Sex was not recorded for 7 participants. \u003csup\u003ed\u003c/sup\u003e Mean IQCODE scores range 1 to 5, higher scores indicating worse cognition \u003csup\u003ee\u003c/sup\u003e IQCODE threshold of mean score\u0026thinsp;\u0026gt;\u0026thinsp;3.3 indicates abnormal test. For example, of the 131 people with dementia, there were 69 who were rated by a spouse informant, and of these 63 (91%) exceeded the abnormal threshold on IQCODE. \u003csup\u003ef\u003c/sup\u003eAD8 scores range from 0 to 8, higher scores indicate worse cognition. \u003csup\u003eg\u003c/sup\u003eAD8 threshold of \u0026ge;2 indicates abnormal test. \u003csup\u003eh\u003c/sup\u003eGPCOGi scores range from 0 to 6, lower scores indicate worse cognition. \u003csup\u003ei\u003c/sup\u003eGPCOGi threshold of \u0026lt;\u0026thinsp;5 indicates abnormal test.\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eTable\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e also shows that people with dementia had higher mean IQCODE and total AD8 scores (median 4.3 and 7 respectively) than people with CIND (median 3.5 and 4 respectively) and normal cognition (median 3.25 and 2 respectively). People with dementia had lower total scores on GPCOGi (median 1) than people with CIND (median 3) and normal cognition (median 4)\u003c/p\u003e \u003cp\u003eInformant Questionnaire Scores by Informant Characteristics\u003c/p\u003e \u003cp\u003eAdult descendants tended to score participants \u003cem\u003emore\u003c/em\u003e cognitively impaired on all three informant questionnaires when compared to spouses as the baseline informant type. However, there was no difference after adjustment for informant age, participant age, informant sex and diagnosis. Friends tended to score participants \u003cem\u003eless\u003c/em\u003e cognitively impaired on all three informant questionnaires when compared to spouses. However, once adjusted for informant age, participant age, informant sex and diagnosis, this difference attenuated for AD8 with modest evidence against the null hypothesis (-1.55, 95% CI -2.74 to -0.36. p\u0026thinsp;=\u0026thinsp;0.01) and there was no difference for IQCODE and GPCOGi. Siblings did not score participants significantly different on all three informant questionnaires when compared to spouses. (Tables\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e and \u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e). There was no association between informant sex and IQCODE, AD8 or GPCOGi score.\u003c/p\u003e \u003cp\u003eWith each additional five years in informant age, informants tended to score participants less cognitively impaired on IQCODE and AD8. However, once adjusted for participant age, informant sex and diagnosis, this difference attenuated for IQCODE and there was no difference for AD8. (Tables\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e and \u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e)\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eInformant Questionnaire Scores by Informant Characteristics, unadjusted\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"6\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colspan=\"6\" nameend=\"c6\" namest=\"c1\"\u003e \u003cp\u003eInformant Relationship Type\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eSpouse\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eAdult descendant\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"2\" nameend=\"c5\" namest=\"c4\"\u003e \u003cp\u003eSibling\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003eFriend\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eIQCODE\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.42\u003c/p\u003e \u003cp\u003e(0.25, 0.59)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c5\" namest=\"c4\"\u003e \u003cp\u003e-0.18\u003c/p\u003e \u003cp\u003e(-0.78, 0.42)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e-0.55\u003c/p\u003e \u003cp\u003e(-0.85, -0.25)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eAD8\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1.73\u003c/p\u003e \u003cp\u003e(1.04, 2.43)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c5\" namest=\"c4\"\u003e \u003cp\u003e0.52\u003c/p\u003e \u003cp\u003e(-1.97, 3.02)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e-2.48\u003c/p\u003e \u003cp\u003e(-3.66, -1.30)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eGPCOGi\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e-0.63\u003c/p\u003e \u003cp\u003e(-1.06, -0.20)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c5\" namest=\"c4\"\u003e \u003cp\u003e-0.24\u003c/p\u003e \u003cp\u003e(-1.80, 1.32)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.81\u003c/p\u003e \u003cp\u003e(0.07, 1.54)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"6\" nameend=\"c6\" namest=\"c1\"\u003e \u003cp\u003e\u003cb\u003eInformant Sex\u003c/b\u003e\u003csup\u003e\u003cb\u003eb\u003c/b\u003e\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colspan=\"3\" nameend=\"c4\" namest=\"c2\"\u003e \u003cp\u003e\u003cb\u003eFemale\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c6\" namest=\"c5\"\u003e \u003cp\u003e\u003cb\u003eMale\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eIQCODE\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"3\" nameend=\"c4\" namest=\"c2\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c6\" namest=\"c5\"\u003e \u003cp\u003e0.09\u003c/p\u003e \u003cp\u003e(-0.10, 0.29)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eAD8\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"3\" nameend=\"c4\" namest=\"c2\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c6\" namest=\"c5\"\u003e \u003cp\u003e-0.03\u003c/p\u003e \u003cp\u003e(-0.82, 0.77)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eGPCOGi\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"3\" nameend=\"c4\" namest=\"c2\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c6\" namest=\"c5\"\u003e \u003cp\u003e-0.15\u003c/p\u003e \u003cp\u003e(-0.61, 0.30)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"6\" nameend=\"c6\" namest=\"c1\"\u003e \u003cp\u003e\u003cb\u003eInformant Age\u003c/b\u003e\u003csup\u003e\u003cb\u003ec\u003c/b\u003e\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colspan=\"5\" nameend=\"c6\" namest=\"c2\"\u003e \u003cp\u003eDifference in score for every additional five years in informant age\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eIQCODE\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"5\" nameend=\"c6\" namest=\"c2\"\u003e \u003cp\u003e-0.06\u003c/p\u003e \u003cp\u003e(-0.09, \u0026minus;\u0026thinsp;0.03)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eAD8\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"5\" nameend=\"c6\" namest=\"c2\"\u003e \u003cp\u003e-0.25\u003c/p\u003e \u003cp\u003e(-0.385, -0.114)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eGPCOGi\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"5\" nameend=\"c6\" namest=\"c2\"\u003e \u003cp\u003e0.04\u003c/p\u003e \u003cp\u003e(-0.04, 0.12)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"6\" nameend=\"c6\" namest=\"c1\"\u003e \u003cp\u003e\u003csup\u003ea\u003c/sup\u003e Difference in score when compared to spouses as the baseline informant type. \u003csup\u003eb\u003c/sup\u003e Difference in score when compared to male as the baseline informant sex. \u003csup\u003ec\u003c/sup\u003e Difference in score when compared to normal cognition as the baseline diagnosis.\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab3\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eInformant Questionnaire Scores by Informant Characteristics, adjusted\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"7\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colspan=\"7\" nameend=\"c7\" namest=\"c1\"\u003e \u003cp\u003eInformant Relationship Type\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e \u003cp\u003eSpouse\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eAdult descendant\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"2\" nameend=\"c6\" namest=\"c5\"\u003e \u003cp\u003eSibling\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c7\"\u003e \u003cp\u003eFriend\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eIQCODE\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e-0.07\u003c/p\u003e \u003cp\u003e(-0.42, 0.28)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c6\" namest=\"c5\"\u003e \u003cp\u003e-0.35\u003c/p\u003e \u003cp\u003e(-0.88, 0.17)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e-0.26\u003c/p\u003e \u003cp\u003e(-0.57, 0.05)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eAD8\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.38\u003c/p\u003e \u003cp\u003e(-1.02, 1.78)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c6\" namest=\"c5\"\u003e \u003cp\u003e0.05\u003c/p\u003e \u003cp\u003e(-2.10, 2.20)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e-1.55\u003c/p\u003e \u003cp\u003e(-2.74, -0.36)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eGPCOGi\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.03\u003c/p\u003e \u003cp\u003e(-0.85, 0.91)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c6\" namest=\"c5\"\u003e \u003cp\u003e0.09\u003c/p\u003e \u003cp\u003e(-1.26, 1.43)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e0.06\u003c/p\u003e \u003cp\u003e(-0.69, 0.80)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"7\" nameend=\"c7\" namest=\"c1\"\u003e \u003cp\u003e\u003cb\u003eInformant Sex\u003c/b\u003e\u003csup\u003e\u003cb\u003eb\u003c/b\u003e\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colspan=\"3\" nameend=\"c4\" namest=\"c2\"\u003e \u003cp\u003e\u003cb\u003eFemale\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"3\" nameend=\"c7\" namest=\"c5\"\u003e \u003cp\u003e\u003cb\u003eMale\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eIQCODE\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"3\" nameend=\"c4\" namest=\"c2\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"3\" nameend=\"c7\" namest=\"c5\"\u003e \u003cp\u003e0.08\u003c/p\u003e \u003cp\u003e(-0.08, 0.24)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eAD8\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"3\" nameend=\"c4\" namest=\"c2\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"3\" nameend=\"c7\" namest=\"c5\"\u003e \u003cp\u003e-0.12\u003c/p\u003e \u003cp\u003e(-0.76, 0.53)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eGPCOGi\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"3\" nameend=\"c4\" namest=\"c2\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"3\" nameend=\"c7\" namest=\"c5\"\u003e \u003cp\u003e-0.10\u003c/p\u003e \u003cp\u003e(-0.50, 0.30)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"7\" nameend=\"c7\" namest=\"c1\"\u003e \u003cp\u003e\u003cb\u003eInformant Age\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colspan=\"6\" nameend=\"c7\" namest=\"c2\"\u003e \u003cp\u003eDifference in score for every additional five years in informant age\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eIQCODE\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"6\" nameend=\"c7\" namest=\"c2\"\u003e \u003cp\u003e-0.06\u003c/p\u003e \u003cp\u003e(-0.12, -0.003)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eAD8\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"6\" nameend=\"c7\" namest=\"c2\"\u003e \u003cp\u003e-0.15\u003c/p\u003e \u003cp\u003e(-0.39, 0.10)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eGPCOGi\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"6\" nameend=\"c7\" namest=\"c2\"\u003e \u003cp\u003e0.01\u003c/p\u003e \u003cp\u003e(-0.14, 0.17)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"7\" nameend=\"c7\" namest=\"c1\"\u003e \u003cp\u003e\u003cb\u003eParticipant Age\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colspan=\"6\" nameend=\"c7\" namest=\"c2\"\u003e \u003cp\u003eDifference in score for every additional five years in participant age\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eIQCODE\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"6\" nameend=\"c7\" namest=\"c2\"\u003e \u003cp\u003e0.09\u003c/p\u003e \u003cp\u003e(0.01, 0.17)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eAD8\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"6\" nameend=\"c7\" namest=\"c2\"\u003e \u003cp\u003e0.12\u003c/p\u003e \u003cp\u003e(-0.22, 0.45)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eGPCOGi\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"6\" nameend=\"c7\" namest=\"c2\"\u003e \u003cp\u003e-0.22\u003c/p\u003e \u003cp\u003e(-0.43, -0.01)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"7\" nameend=\"c7\" namest=\"c1\"\u003e \u003cp\u003e\u003cb\u003eDiagnosis\u003c/b\u003e\u003csup\u003e\u003cb\u003ec\u003c/b\u003e\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cb\u003eNormal cognition\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"3\" nameend=\"c5\" namest=\"c3\"\u003e \u003cp\u003e\u003cb\u003eCIND\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c7\" namest=\"c6\"\u003e \u003cp\u003e\u003cb\u003eDementia\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eIQCODE\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"3\" nameend=\"c5\" namest=\"c3\"\u003e \u003cp\u003e0.31\u003c/p\u003e \u003cp\u003e(0.1, 0.53)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c7\" namest=\"c6\"\u003e \u003cp\u003e0.76\u003c/p\u003e \u003cp\u003e(0.56, 0.96)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eAD8\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"3\" nameend=\"c5\" namest=\"c3\"\u003e \u003cp\u003e1.11\u003c/p\u003e \u003cp\u003e(0.25, 1.98)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c7\" namest=\"c6\"\u003e \u003cp\u003e3.36\u003c/p\u003e \u003cp\u003e(2.55, 4.16)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eGPCOGi\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"3\" nameend=\"c5\" namest=\"c3\"\u003e \u003cp\u003e-0.78\u003c/p\u003e \u003cp\u003e(-1.32, -0.24)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c7\" namest=\"c6\"\u003e \u003cp\u003e-1.84\u003c/p\u003e \u003cp\u003e(-2.34, -1.34)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"7\" nameend=\"c7\" namest=\"c1\"\u003e \u003cp\u003eAdjusted for informant type, informant sex, informant age, participant age and diagnosis.\u003c/p\u003e \u003cp\u003e\u003csup\u003ea\u003c/sup\u003e Difference in score when compared to spouses as the baseline informant type. \u003csup\u003eb\u003c/sup\u003e Difference in score when compared to male as the baseline informant sex. \u003csup\u003ec\u003c/sup\u003e Difference in score when compared to normal cognition as the baseline diagnosis.\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eDiagnostic accuracy\u003c/p\u003e \u003cp\u003eThe diagnostic accuracy of IQCODE, AD8 and GPCOGi are summarised in Tables\u0026nbsp;\u003cspan refid=\"Tab4\" class=\"InternalRef\"\u003e4\u003c/span\u003e, \u003cspan refid=\"Tab5\" class=\"InternalRef\"\u003e5\u003c/span\u003e and \u003cspan refid=\"Tab6\" class=\"InternalRef\"\u003e6\u003c/span\u003e respectively.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab4\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 4\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eAccuracy of informant judgement for the diagnosis of dementia using IQCODE\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"6\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eAUROC\u003c/p\u003e \u003cp\u003e(95 CI %)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eSensitivity\u003c/p\u003e \u003cp\u003e(95 CI %)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eSpecificity\u003c/p\u003e \u003cp\u003e(95 CI %)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003ePPV\u003c/p\u003e \u003cp\u003e(95 CI %)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003eNPV\u003c/p\u003e \u003cp\u003e(95 CI %)\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eOverall\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.67\u003c/p\u003e \u003cp\u003e(0.62, 0.72)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e95\u003c/p\u003e \u003cp\u003e(90, 98)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e38\u003c/p\u003e \u003cp\u003e(29, 48)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e67\u003c/p\u003e \u003cp\u003e(60, 74)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e86\u003c/p\u003e \u003cp\u003e(73, 95)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"6\" nameend=\"c6\" namest=\"c1\"\u003e \u003cp\u003eInformant Relationship Type\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSpouse\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.62\u003c/p\u003e \u003cp\u003e(0.55, 0.69)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e91\u003c/p\u003e \u003cp\u003e(82, 97)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e33\u003c/p\u003e \u003cp\u003e(22, 47)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e61\u003c/p\u003e \u003cp\u003e(51, 71)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e77\u003c/p\u003e \u003cp\u003e(56, 91)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAdult descendant\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.63\u003c/p\u003e \u003cp\u003e(0.54, 0.71)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e100\u003c/p\u003e \u003cp\u003e(94, 100)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e25\u003c/p\u003e \u003cp\u003e(10,47)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e76\u003c/p\u003e \u003cp\u003e(64, 85)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e100\u003c/p\u003e \u003cp\u003e(54, 100)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSibling\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.75\u003c/p\u003e \u003cp\u003e(0.26, 1)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e100\u003c/p\u003e \u003cp\u003e(16, 100)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e50\u003c/p\u003e \u003cp\u003e(1, 99)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e67\u003c/p\u003e \u003cp\u003e(9, 99)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e100\u003c/p\u003e \u003cp\u003e(3, 100)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eFriend\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.89\u003c/p\u003e \u003cp\u003e(0.78, 1)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e100\u003c/p\u003e \u003cp\u003e(40, 100)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e79\u003c/p\u003e \u003cp\u003e(49, 95)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e57\u003c/p\u003e \u003cp\u003e(18, 90)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e100\u003c/p\u003e \u003cp\u003e(72, 100)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"6\" nameend=\"c6\" namest=\"c1\"\u003e \u003cp\u003eInformant Sex\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMale\u003c/p\u003e \u003cp\u003einformant\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.74\u003c/p\u003e \u003cp\u003e(0.63, 0.85)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e97\u003c/p\u003e \u003cp\u003e(86, 100)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e50\u003c/p\u003e \u003cp\u003e(28, 72)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e77\u003c/p\u003e \u003cp\u003e(62, 88)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e92\u003c/p\u003e \u003cp\u003e(62, 100)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eFemale informant\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.63\u003c/p\u003e \u003cp\u003e(0.57, 0.69)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e95\u003c/p\u003e \u003cp\u003e(88, 98)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e32\u003c/p\u003e \u003cp\u003e(21, 44)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e64\u003c/p\u003e \u003cp\u003e(56, 72)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e82\u003c/p\u003e \u003cp\u003e(63, 94)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"6\" nameend=\"c6\" namest=\"c1\"\u003e \u003cp\u003eAUROC\u0026thinsp;=\u0026thinsp;areas under the receiver operating characteristic curve. PPV\u0026thinsp;=\u0026thinsp;positive predictive value. NPV\u0026thinsp;=\u0026thinsp;negative predictive value. 95% CI\u0026thinsp;=\u0026thinsp;95% Confidence interval\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab5\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 5\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eAccuracy of informant judgement for the diagnosis of dementia using AD8\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"6\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eAUROC\u003c/p\u003e \u003cp\u003e(95 CI %)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eSensitivity\u003c/p\u003e \u003cp\u003e(95 CI %)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eSpecificity\u003c/p\u003e \u003cp\u003e(95 CI %)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003ePPV\u003c/p\u003e \u003cp\u003e(95 CI %)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003eNPV\u003c/p\u003e \u003cp\u003e(95 CI %)\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eOverall\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.64\u003c/p\u003e \u003cp\u003e(0.60, 0.69)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e97\u003c/p\u003e \u003cp\u003e(92, 99)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e32\u003c/p\u003e \u003cp\u003e(23, 42)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e64\u003c/p\u003e \u003cp\u003e(56, 70)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e90\u003c/p\u003e \u003cp\u003e(75, 97)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"6\" nameend=\"c6\" namest=\"c1\"\u003e \u003cp\u003e\u003cb\u003eInformant Relationship Type\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSpouse\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.61\u003c/p\u003e \u003cp\u003e(0.55, 0.67)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e94\u003c/p\u003e \u003cp\u003e(86, 98)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e28\u003c/p\u003e \u003cp\u003e(17, 40)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e58\u003c/p\u003e \u003cp\u003e(48, 67)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e82\u003c/p\u003e \u003cp\u003e(60, 95)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAdult descendant\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.56\u003c/p\u003e \u003cp\u003e(0.50, 0.63)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e100\u003c/p\u003e \u003cp\u003e(94, 100)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e13\u003c/p\u003e \u003cp\u003e(3,32)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e73\u003c/p\u003e \u003cp\u003e(61, 82)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e100\u003c/p\u003e \u003cp\u003e(30, 100)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSibling\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.7\u003c/p\u003e \u003cp\u003e(0.26, 1)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e100\u003c/p\u003e \u003cp\u003e(16, 100)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e50\u003c/p\u003e \u003cp\u003e(1, 99)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e67\u003c/p\u003e \u003cp\u003e(9, 99)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e100\u003c/p\u003e \u003cp\u003e(3, 100)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eFriend\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.88\u003c/p\u003e \u003cp\u003e(0.77, 0.99)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e100\u003c/p\u003e \u003cp\u003e(40, 100)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e75\u003c/p\u003e \u003cp\u003e(48, 93)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e50\u003c/p\u003e \u003cp\u003e(16, 84)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e100\u003c/p\u003e \u003cp\u003e(74, 100)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"6\" nameend=\"c6\" namest=\"c1\"\u003e \u003cp\u003e\u003cb\u003eInformant Sex\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMale\u003c/p\u003e \u003cp\u003einformant\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.72\u003c/p\u003e \u003cp\u003e(0.62, 0.82)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e100\u003c/p\u003e \u003cp\u003e(91, 100)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e44\u003c/p\u003e \u003cp\u003e(24, 65)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e73\u003c/p\u003e \u003cp\u003e(58, 84)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e100\u003c/p\u003e \u003cp\u003e(72, 100)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eFemale informant\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.60\u003c/p\u003e \u003cp\u003e(0.55, 0.66)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e96\u003c/p\u003e \u003cp\u003e(89, 99)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e25\u003c/p\u003e \u003cp\u003e(16, 36)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e61\u003c/p\u003e \u003cp\u003e(53, 69)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e83\u003c/p\u003e \u003cp\u003e(61, 95)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"6\" nameend=\"c6\" namest=\"c1\"\u003e \u003cp\u003eAUROC\u0026thinsp;=\u0026thinsp;areas under the receiver operating characteristic curve. PPV\u0026thinsp;=\u0026thinsp;positive predictive value. NPV\u0026thinsp;=\u0026thinsp;negative predictive value 95%. CI 95%. Confidence interval\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab6\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 6\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eAccuracy of informant judgement for the diagnosis of dementia using GPCOGi\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"6\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eAUROC\u003c/p\u003e \u003cp\u003e(95 CI %)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eSensitivity\u003c/p\u003e \u003cp\u003e(95 CI %)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eSpecificity\u003c/p\u003e \u003cp\u003e(95 CI %)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003ePPV\u003c/p\u003e \u003cp\u003e(95 CI %)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003eNPV\u003c/p\u003e \u003cp\u003e(95 CI %)\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eOverall\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.59\u003c/p\u003e \u003cp\u003e(0.56, 0.63)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e99\u003c/p\u003e \u003cp\u003e(96, 100)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e20\u003c/p\u003e \u003cp\u003e(13, 28)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e60\u003c/p\u003e \u003cp\u003e(53, 67)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e96\u003c/p\u003e \u003cp\u003e(77, 100)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"6\" nameend=\"c6\" namest=\"c1\"\u003e \u003cp\u003e\u003cb\u003eInformant Relationship Type\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSpouse\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.58\u003c/p\u003e \u003cp\u003e(0.53, 0.63)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e99\u003c/p\u003e \u003cp\u003e(92, 100)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e17\u003c/p\u003e \u003cp\u003e(9, 28)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e56\u003c/p\u003e \u003cp\u003e(47, 65)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e92\u003c/p\u003e \u003cp\u003e(62, 100)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAdult descendant\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.58\u003c/p\u003e \u003cp\u003e(0.51, 0.66)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e100\u003c/p\u003e \u003cp\u003e(94, 100)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e17\u003c/p\u003e \u003cp\u003e(5, 37)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e74\u003c/p\u003e \u003cp\u003e(62, 83)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e100\u003c/p\u003e \u003cp\u003e(40, 100)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSibling\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eFriend\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.69\u003c/p\u003e \u003cp\u003e(0.57, 0.81)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e100\u003c/p\u003e \u003cp\u003e(40, 100)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e38\u003c/p\u003e \u003cp\u003e(15, 64)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e29\u003c/p\u003e \u003cp\u003e(8, 58)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e100\u003c/p\u003e \u003cp\u003e(54, 100)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"6\" nameend=\"c6\" namest=\"c1\"\u003e \u003cp\u003e\u003cb\u003eInformant Sex\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMale\u003c/p\u003e \u003cp\u003einformant\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.62\u003c/p\u003e \u003cp\u003e(0.54, 0.71)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e100\u003c/p\u003e \u003cp\u003e(91, 100)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e24\u003c/p\u003e \u003cp\u003e(9, 45)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e66\u003c/p\u003e \u003cp\u003e(52, 54)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e100\u003c/p\u003e \u003cp\u003e(54, 100)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eFemale informant\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.57\u003c/p\u003e \u003cp\u003e(0.53, 0.62)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e99\u003c/p\u003e \u003cp\u003e(94, 100)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e16\u003c/p\u003e \u003cp\u003e(8, 26)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e59\u003c/p\u003e \u003cp\u003e(51, 67)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e92\u003c/p\u003e \u003cp\u003e(64, 100)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"6\" nameend=\"c6\" namest=\"c1\"\u003e \u003cp\u003eAUROC\u0026thinsp;=\u0026thinsp;areas under the receiver operating characteristic curve. PPV\u0026thinsp;=\u0026thinsp;positive predictive value. NPV\u0026thinsp;=\u0026thinsp;negative predictive value 95%. CI 95% = Confidence interval\u003c/p\u003e \u003cp\u003e\u003csup\u003ea\u003c/sup\u003eAll four informants classed as siblings categorised patient participants as impaired on GPCOGi\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eAll informants\u003c/p\u003e \u003cp\u003eOverall sensitivity was 95% (95% CI 90\u0026ndash;98%) for IQCODE, 97% (95% CI 92\u0026ndash;99%) for AD8 and 99% (95% CI 96\u0026ndash;100%) for GCPOGi. Overall specificity was 38% (95% CI 29\u0026ndash;48%) for IQCODE, 32% (95% CI 23\u0026ndash;42%) for AD8 and 20% (95% CI 13\u0026ndash;28%) for GPCOGi.\u003c/p\u003e \u003cp\u003eOverall accuracy was similar for all informant questionnaires with area under the receiver operating characteristic curve (AUROC) of 0.67 (95% CI, 0.62 to 0.72) for IQCODE, 0.64 (95% CI, 0.60 to 0.69) for AD8 and 0.59 (95% CI, 0.56 to 0.63) for GPCOGi, though the 95% confidence intervals only just overlapped for IQCODE and GPCOGi.\u003c/p\u003e \u003cp\u003eInformants by Relationship Type\u003c/p\u003e \u003cp\u003eSensitivity was consistently high across all informant relationship types for all three informant questionnaires. Sensitivity by informant relationship type ranged from 91\u0026ndash;100% for IQCODE, 94\u0026ndash;100% for AD8 and 99% to100% for GPCOGI. Spouses tended to have the lowest sensitivity. However, sensitivity CIs overlap across all informant types on IQCODE, AD8 and GPCOGi and these differences were consistent with chance.\u003c/p\u003e \u003cp\u003eSpecificity was lower across all informant relationship types for all three informant questionnaires. Specificity by informant relationship type ranged from 25\u0026ndash;79% for IQCODE, 13\u0026ndash;75% for AD8 and 17\u0026ndash;38% for GPCOGi. Adult descendants tended to have the lowest specificity at 25% (95% CI 10\u0026ndash;47%) for IQCODE, 13% (95% CI 3\u0026ndash;32%) for AD8 and 17% (95% CI 5\u0026ndash;37%) for GPCOGi. Friends tended to have the highest specificity at 79% (95% CI 49\u0026ndash;95%) for IQCODE, 75% (95% CI 48\u0026ndash;93%) for AD8 and 38% (95% CI 15\u0026ndash;64%) for GPCOGi.\u003c/p\u003e \u003cp\u003eAUROC by informant relationship type ranged from 0.62 to 0.89 for IQCODE, 0.56 to 0.88 for AD8 and 0.58 to 0.69 for GPCOGi. Friends tended to have the highest AUROC at 0.89 (95% CI 0.78 to 1) for IQCODE, 0.88 (95% CI 0.77 to 0.99) for AD8 and 0.69 (95% CI 0.57 to 0.81) for GPCOGi. It was not possible to calculate a p value for GPCOGi because there were zero siblings who rated their participant as being cognitively healthy. However, there was strong evidence against the null hypothesis of no difference by informant type for IQCODE (p\u0026thinsp;=\u0026thinsp;0.0004) and AD8 (p\u0026thinsp;=\u0026thinsp;0.0001), suggesting that overall friends are more accurate when using IQCODE and AD8, due to an increase in the specificity (that is, ability to detect correctly someone without dementia), without loss of sensitivity.\u003c/p\u003e \u003cp\u003eThere was substantial uncertainty in the estimates for friends and siblings with large confidence intervals, as there were small numbers of these informants.\u003c/p\u003e \u003cp\u003eInformants by Sex\u003c/p\u003e \u003cp\u003eFemales had a higher AUROC for all three tests, driven by higher specificity for females. However, 95% CIs overlapped and were consistent with chance.\u003c/p\u003e \u003cp\u003eMissing IQCODE scores\u003c/p\u003e \u003cp\u003eWe found no association between informant sex and missing IQCODE. The odds ratio for not completing IQCODE was 2.1 (95% 0.46 to 9.6, p\u0026thinsp;=\u0026thinsp;0.35) when male informants were compared to female informants.\u003c/p\u003e \u003cp\u003eWe did find an association between missing IQCODE and informant age. The seven informants who did not complete IQCODE were on average 12 years older (95% CI 2 years to 21 years) than those who did complete the IQCODE; t test p\u0026thinsp;=\u0026thinsp;0.02.\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eThis is the first study to our knowledge to explore diagnostic accuracy by informant relationship type. Overall, all three informant tests had relatively high sensitivity, low specificity and had a similar AUROC. Compared to spouses, adult descendants tended to score participants more cognitively impaired, whereas friends scored participants less cognitively impaired on all three questionnaires. However, there was little evidence of scoring difference by informant relationship type once fully adjusted, except for friends who scored participants lower on AD8. Friends tended to have the best overall diagnostic accuracy with the highest AUROC for IQCODE, AD8 and GPCOGi.\u003c/p\u003e\n\u003ch3\u003eComparison with existing literature\u003c/h3\u003e\n\u003cp\u003eAlthough common thresholds for detecting dementia using IQCODE tend to be applied (often ranging from 3.3 to 3.6), there is no universally accepted threshold, making comparison across studies challenging [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e]. Previous literature, which considers studies with varying thresholds, suggests a pooled estimate of IQCODE sensitivity of 80\u0026ndash;91% and specificity of 65\u0026ndash;85% but study quality is noted to be poor [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]. A systematic review found only one previous suitable study conducted in primary care [\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e]. The identified study had a sensitivity of 100% and specificity of 82% using a threshold of 3.3. The study reported a decreasing sensitivity and increasing specificity as the threshold increased and suggested an optimal cut-point of 3.35 using AUROC analyses [\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e]. We found a similarly high sensitivity but a notably lower specificity in comparison to that study which may reflect aspects of the study design. For example, the other study conducted IQCODE over the telephone, had a lower prevalence of dementia (7% compared to 54% in our study), had a similar proportion of informants that were a spouse (47%), and was assessed as being at high risk of bias in all four Quality Assessment of Diagnostic Accuracy Studies (QUADAS) domains [\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e, \u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eThe original author for AD8 defined a threshold of 2 [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]. However, systematic reviews identified that thresholds applied in studies have differed and result in differing test performance [\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e, \u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e]. For example, a systematic review looking at the use of AD8 across healthcare settings found a sensitivity of 92% and specificity of 64% at a threshold of \u0026ge;\u0026thinsp;2 compared to a sensitivity of 91% and specificity of 76% at a threshold of \u0026ge;\u0026thinsp;3 [\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e]. The systematic review identified only one study in a primary care setting which reported a sensitivity of 90% and specificity of 88% using a threshold of \u0026ge;\u0026thinsp;3 [\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e]. We found a similar sensitivity of 97%, but lower specificity of 32% using a threshold of \u0026ge;\u0026thinsp;2. The other study in primary care was assessed as being at risk of bias in one QUADAS domain and unclear in two [\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eThere is less data available to evaluate the use of GPCOG. The original study reported a sensitivity of 85% and specificity of 86% when used as the full two-stage questionnaire. The informant component used in isolation had a reported sensitivity of 89% and specificity of 66% [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]. We found higher sensitivity, 99%, and a notably lower specificity, 20%, in comparison to the original study which may reflect aspects of the study design. We only included those over age 70 where a concern about cognition had been raised and there was no formal diagnosis of dementia. However, the original GPCOG study included all adults over 75 regardless of cognitive status and those aged 50 to 74 with suspected cognitive impairment [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eAll informants completed AD8 and GPCOG. This is consistent with their reported ease of administration including fast completion and minimal training requirements [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e, \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e]. Not all informants completed IQCODE in this study, but completion was still high at 97%. An in-hospital study found poor uptake and completion rate of IQCODE by informants. It is likely that this reflected the inpatient nature of the study, and the authors suggested that short admissions and relatives being away from the ward during working hours may have been contributing factors [\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e]. Conversely, a community study suggested IQCODE was acceptable to informants and easy to use, which is in keeping with our findings [\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eInformant characteristics may influence test scores. However, reported data on the influence of informant characteristics is limited and variable. One study reported that the age of informants who were wives was not associated with IQCODE scoring [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e, \u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]. When considering all informant types, we found older informants scored participants less cognitively impaired on IQCODE. We found no association between AD8 or GPCOGi score and informant age when adjusted for informant sex and informant type.\u003c/p\u003e \u003cp\u003eSome investigators have reported that IQCODE is not influenced by relationship type or length [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e], whereas others have found that spouses reported better cognitive function for patients than non-spouses [\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e]. We found that friends, compared to spouses, tended to score participants less cognitively impaired on IQCODE and also AD8.\u003c/p\u003e \u003cp\u003eStrengths and limitations\u003c/p\u003e \u003cp\u003e We recruited a representative group of participants from several GP surgeries, across a geographically diverse area. Our findings are therefore likely to closely reflect clinical practice in the United Kingdom. Although we made efforts to maximise inclusion, including providing translation services, participants were mostly white, native English speakers. IQCODE is, however, thought to be relatively unaffected by language and AD8 has been translated and validated in a variety of languages [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e, \u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e]. This study has limited applicability to people with advanced cognitive impairment, since we excluded those people.\u003c/p\u003e \u003cp\u003eThe uncertainty in the estimates increases when analysing by informant subtype, which limits the extent to which we can draw comparisons between categories; the number of informants in the sibling category was especially small, with large confidence intervals. Whilst we would expect informants attending the research clinic to mirror similar patterns to those who may routinely accompany patients to appointments, we could not investigate this formally. Index test informant measures (IQCODE, AD8, GPCOGi) were not used by the expert assessors when deciding the reference standard diagnosis, but the same informant who completed these index tests contributed to the expert evaluation and completed BADL, though this formed only one part of the holistic expert judgement about the diagnosis.\u003c/p\u003e \u003cp\u003eWe applied a commonly used threshold for IQCODE and AD8, but there are a range of thresholds [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e, \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e, \u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e]. The accuracy at other thresholds may be different. An alternative approach for primary care could be to apply a threshold which optimises for specificity and therefore the use of informant questionnaires to rule in dementia, minimising overdiagnosis and associated psychological harm. However, further analysis exploring the influence of threshold by informant relationship type would be required.\u003c/p\u003e \u003cp\u003eGPCOG consists of two components, a patient and informant questionnaire but we evaluated the informant component of GPCOG in isolation because we were interested specifically in informant characteristics [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e].\u003c/p\u003e"},{"header":"Conclusion","content":"\u003cp\u003eOverall, informants, of any relationship type, when using IQCODE, AD8 or GPCOGi may be useful for ruling out dementia but not for ruling it in. We found little difference between spouse and adult descendants, who made around 90% of informants. In contrast only 8% of informants were a friend, but they performed significantly better overall on IQCODE and AD8 due to an increase in specificity without loss of sensitivity.\u003c/p\u003e \u003cp\u003eAD8 and GPCOGi have fewer items than IQCODE and are arguably less time-consuming in a traditional consultation. However, with the increasing use of e-consultations, this may be less of a consideration as informant questionnaires could be sent electronically, or posted, prior to an appointment.\u003c/p\u003e \u003cp\u003eIf an informant questionnaire does not suggest impaired cognition, this could guide the consultation to consider alternative causes for the presentation such as hearing or visual impairment or mood disorders. Indeed, one option in people over 70 years, who do not report otherwise seriously distressing symptoms, would be to use a normal IQCODE, AD8 or GPCOGi to avoid prolonged and burdensome diagnostic pathways for patients and carers, recognising that if patients or their family desired further tests then clinicians could (perhaps should) offer these. Future research should examine how informants rating of cognition might change over time and whether this differs by type of informant.\u003c/p\u003e \u003cp\u003eWhere IQCODE, AD8 or GPCOGi scoring is suggestive of dementia, we believe clinicians should use a further tool with high specificity to avoid misdiagnosis. In our related paper from the same study, we found that GP judgement was highly specific but poorly sensitive [\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e]. Given the low burden of both GP judgement and informant questionnaires, a further area of research would be to consider whether combining both these tools could achieve reasonable diagnostic accuracy in general practice.\u003c/p\u003e \u003cp\u003eInformants provide invaluable information in helping assess the clinical diagnosis of dementia. We find little empirical evidence that the type of informant is important in ruling out a diagnosis but may differ if trying to rule in a diagnosis.\u003c/p\u003e"},{"header":"Abbreviations","content":"\u003cp\u003e\u003cstrong\u003e\u003cem\u003eACE-III:\u003c/em\u003e\u003c/strong\u003e Addenbrooke\u0026rsquo;s Cognitive Examination III\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cem\u003eAUROC:\u003c/em\u003e\u003c/strong\u003e Area under receiver operator curve\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cem\u003eBADL:\u003c/em\u003e\u003c/strong\u003e Bristol Activities of Daily Living\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cem\u003eBASDEC:\u003c/em\u003e\u003c/strong\u003e Brief Assessment Schedule Depression Cards\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cem\u003eBNSSG:\u0026nbsp;\u003c/em\u003e\u003c/strong\u003eBristol, North Somerset and South Gloucestershire\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cem\u003eCIND:\u003c/em\u003e\u003c/strong\u003e Cognitive impairment not dementia\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cem\u003eGP:\u003c/em\u003e\u003c/strong\u003e General Practitioner/Practice\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cem\u003eGPCOG:\u003c/em\u003e\u003c/strong\u003e General Practitioner Assessment of Cognition\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cem\u003eGPCOGi:\u0026nbsp;\u003c/em\u003e\u003c/strong\u003e\u003cem\u003einformant component of\u0026nbsp;\u003c/em\u003eGeneral Practitioner Assessment of Cognition\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cem\u003eICD-10:\u003c/em\u003e\u003c/strong\u003e International Classification of Disease 10th Revision\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cem\u003eIQCODE:\u0026nbsp;\u003c/em\u003e\u003c/strong\u003eInformant Questionnaire on Cognitive Decline in the Elderly\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cem\u003eNICE:\u0026nbsp;\u003c/em\u003e\u003c/strong\u003eNational Institute for Health and Care Excellence\u003c/p\u003e"},{"header":"Declarations","content":"\u003ch2\u003eEthnics approval and consent to participate\u0026nbsp;\u003c/h2\u003e\n\u003cp\u003eThe National Research Ethics Service Committee London – Bromley (reference 14/LO/2025) gave a favourable ethical opinion on 25 November 2014. NHS Research and Development approvals were granted by Avon Primary Care Research Collaboration on behalf of Bristol, North Somerset and South Gloucestershire clinical commissioning groups. The University of Bristol acted as Sponsor.\u003c/p\u003e\n\u003ch2\u003eConsent for publication\u003c/h2\u003e\n\u003cp\u003eNot applicable.\u003c/p\u003e\n\u003ch2\u003eAvailability of data and materials\u0026nbsp;\u003c/h2\u003e\n\u003cp\u003eThe datasets used and analysed during the current study are available from the corresponding author on reasonable request.\u003c/p\u003e\n\u003ch2\u003eCompeting interests\u003c/h2\u003e\n\u003cp\u003eThe authors declare no competing interest.\u003c/p\u003e\n\u003ch2\u003eFunding\u003c/h2\u003e\n\u003cp\u003eThe research reported in this publication was funded through The Wellcome Trust (Fellowship 108804/Z/15/z), Avon Primary Care Research Collaboration, The Claire Wand fund, and the National Institute for Health Research School for Primary Care Research. The Western Clinical Research Networks approved an application for service support costs for practices to provide for the expense of room hire in GP surgeries and GPs referring people to the study.\u003c/p\u003e\n\u003ch2\u003eAuthor contributions\u003c/h2\u003e\n\u003cp\u003eJC and STC prepared the main manuscript including data analysis, interpretation and preparation of all tables and figures. All authors contributed to conception of the research question and review of the manuscript.\u003c/p\u003e\n\u003ch2\u003eAcknowledgements\u003c/h2\u003e\n\u003cp\u003eThe authors thank the participants and the staff at participating practices, without whom this work would not have been possible. The staff at the West of England Clinical Research Network arranged for redaction, collection, and transport of medical records from general practices.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eNational Institute for Health and Care Excellence. Dementia: What is it? https://cks.nice.org.uk/topics/dementia/backgroun d-information/definition/. Accessed 5 June 2024.\u003c/li\u003e\n\u003cli\u003eAlzheimer\u0026apos;s Society. Alzheimer\u0026rsquo;s Society\u0026rsquo;s view on diagnosis and assessment. https://www.alzheimers.org.uk/about-us/policy-and-influencing/what-we-think/diagnosis-assessment. Accessed 5 June 2024.\u003c/li\u003e\n\u003cli\u003eManthorpe J, Samsi K, Campbell S, Abley C, Keady J, Bond J, et al. From forgetfulness to dementia: clinical and commissioning implications of diagnostic experiences. British Journal of General Practice. 2013;63:e69\u0026ndash;75.\u003c/li\u003e\n\u003cli\u003eWittenberg R, Hu B, Barraza-Araiza LF, Rehill A. Projections of Older People with Dementia and Costs of Dementia Care in the United Kingdom, 2019-2040. CPEC Working Paper 5. 2019; November:1\u0026ndash;79.\u003c/li\u003e\n\u003cli\u003eNHS England. Dementia. https://www.england.nhs.uk/mental-health/dementia/. Accessed 5 June 2024.\u003c/li\u003e\n\u003cli\u003eNational Institute for Health and Care Excellence. Dementia: assessment, management and support for people living with dementia and their carers. NICE Guideline (NG97). https://www.nice.org.uk/guidance/ng97/chapter/Recommendations#diagnosis. Accessed 5 June 2024.\u003c/li\u003e\n\u003cli\u003eJames Lind Alliance. Dementia Top 10 | https://www.jla.nihr.ac.uk/priority-setting-partnerships/dementia/top-10-priorities/. Accessed 5 June 2024.\u003c/li\u003e\n\u003cli\u003eJorm AF. A short form of the Informant Questionnaire on Cognitive Decline in the Elderly (IQCODE): development and cross-validation. Psychol Med. 1994;24:145\u0026ndash;53.\u003c/li\u003e\n\u003cli\u003eGalvin JE, Roe CM, Powlishta KK, Coats MA, Muich SJ, Grant E, et al. The AD8: brief informant interview to detect dementia. Neurology. 2005;65:559\u0026ndash;64.\u003c/li\u003e\n\u003cli\u003eBrodaty H, Pond D, Kemp NM, Luscombe G, Harding L, Berman K, et al. The GPCOG: A New Screening Test for Dementia Designed for General Practice. J Am Geriatr Soc. 2002;50:530\u0026ndash;4.\u003c/li\u003e\n\u003cli\u003eTaylor-Rowan M, Nafisi S, Owen R, Duffy R, Patel A, Burton JK, et al. Informant-based screening tools for dementia: an overview of systematic reviews. Psychol Med. 2023;53:580-9.\u003c/li\u003e\n\u003cli\u003eJorm AF, Broe GA, Creasey H, Sulway MR, Dent O, Fairley MJ, et al. Further data on the validity of the informant questionnaire on cognitive decline in the elderly (IQCODE). Int J Geriatr Psychiatry. 1996;11:131-9.\u003c/li\u003e\n\u003cli\u003eFuh JL, Teng EL, Lin KN, Larson EB, Wang SJ, Liu CY, et al. The Informant Questionnaire on Cognitive Decline in the Elderly (IQCODE) as a screening tool for dementia for a predominantly illiterate Chinese population. Neurology. 1995;45:92\u0026ndash;6.\u003c/li\u003e\n\u003cli\u003eOffice for National Statistics. Health geographies population estimates (Accredited official statistics). https://www.ons.gov.uk/peoplepopulationandcommunity/populationandmigration/populationestimates/datasets/clinicalcommissioninggroupmidyearpopulationestimates. Accessed 5 June 2024.\u003c/li\u003e\n\u003cli\u003eCreavin ST, Haworth J, Fish M, Cullum S, Bayer A, Purdy S, et al. Clinical judgment of GPs for the diagnosis of dementia: a diagnostic test accuracy study. BJGP Open. 2021; 5(5):BJGPO.2021.0058.\u003c/li\u003e\n\u003cli\u003eICD-10 Version:2019. https://icd.who.int/browse10/2019/en#/F00-F09. Accessed 5 June 2024.\u003c/li\u003e\n\u003cli\u003ePetersen RC. Mild cognitive impairment as a diagnostic entity. J Intern Med. 2004;256:183\u0026ndash;94.\u003c/li\u003e\n\u003cli\u003eJorm AF. The Informant Questionnaire on Cognitive Decline in the Elderly (IQCODE): a review. Int Psychogeriatr. 2004;16:275\u0026ndash;93.\u003c/li\u003e\n\u003cli\u003eHarrison JK, Fearon P, Noel-Storr AH, McShane R, Stott DJ, Quinn TJ. Informant Questionnaire on Cognitive Decline in the Elderly (IQCODE) for the diagnosis of dementia within a general practice (primary care) setting. Cochrane Database of Systematic Reviews. 2014;7:CD010771.\u003c/li\u003e\n\u003cli\u003eTokuhara KG, Valcour VG, Masaki KH, Blanchette PL. Utility of the Informant Questionnaire on Cognitive Decline in the Elderly (IQCODE) for dementia in a Japanese-American population. Hawaii Med J. 2006;65:72\u0026ndash;5.\u003c/li\u003e\n\u003cli\u003eChen HH, Sun FJ, Yeh TL, Liu HE, Huang HL, Kuo BIT, et al. The diagnostic accuracy of the Ascertain Dementia 8 questionnaire for detecting cognitive impairment in primary care in the community, clinics and hospitals: a systematic review and meta-analysis. Fam Pract. 2018;35:239-46.\u003c/li\u003e\n\u003cli\u003eHendry K, Green C, McShane R, Noel-Storr AH, Stott DJ, Anwer S, et al. AD‐8 for detection of dementia across a variety of healthcare settings. Cochrane Database Syst Rev. 2019;3:CD011121.\u003c/li\u003e\n\u003cli\u003eChan QL, Xu X, Shaik MA, Chong SST, Hui RJY, Chen CLH, et al. Clinical Utility of the Informant AD8 as a Dementia Case Finding Instrument in Primary Healthcare. JAlzheimers Dis. 2016;49:121\u0026ndash;7.\u003c/li\u003e\n\u003cli\u003eBloomfield K, John N. Informant Questionnaire on Cognitive Decline in the Elderly (IQCODE) completion on an acute care ward for the elderly: a brief study of informant characteristics. Int Psychogeriatr. 2012;24:1700\u0026ndash;1.\u003c/li\u003e\n\u003cli\u003eHancock P, Larner AJ. Diagnostic utility of the Informant Questionnaire on Cognitive Decline in the Elderly (IQCODE) and its combination with the Addenbrooke\u0026rsquo;s Cognitive Examination-Revised (ACE-R) in a memory clinic-based population. Int Psychogeriatr. 2009;21:526\u0026ndash;30.\u003c/li\u003e\n\u003cli\u003eNygaard HA, Naik M, Geitung JT. The Informant Questionnaire on Cognitive Decline in the Elderly (IQCODE) is associated with informant stress. Int J Geriatr Psychiatry. 2009;24:1185\u0026ndash;91.\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"bmc-primary-care","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"famp","sideBox":"Learn more about [BMC Primary Care](https://bmcprimcare.biomedcentral.com/)","snPcode":"","submissionUrl":"https://author-welcome.nature.com/12875","title":"BMC Primary Care","twitterHandle":"BMC_series","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"Dementia, informant, relationship, accuracy, IQCODE, AD8, GPCOG, primary care","lastPublishedDoi":"10.21203/rs.3.rs-4637777/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-4637777/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003eBackground\u003c/h2\u003e\n\u003cp\u003eIncreasing numbers of people are requiring evaluation for possible dementia. There has been limited research exploring the accuracy of informant questionnaires in primary care.\u003c/p\u003e\n\u003ch2\u003eMethods\u003c/h2\u003e\n\u003cp\u003eA diagnostic accuracy study to explore the influence of informant relationship type on the accuracy of IQCODE, AD8 and GPCOGi in primary care.\u003c/p\u003e\n\u003cp\u003e240 participants were recruited from 21 general practitioner (GP) surgeries in the South West of England.\u003c/p\u003e\n\u003cp\u003eThe reference standard for a diagnosis of dementia was made against ICD-10 criteria based on specialist clinician assessment. A threshold of greater than 3.3 on IQCODE, greater or equal to 2 on AD8 and less than 5 on the informant component of GPCOG (GPCOGi) was used to indicate an abnormal test.\u003c/p\u003e\n\u003ch2\u003eResults\u003c/h2\u003e\n\u003cp\u003eOf 238 participants with informant data, 131 had dementia, 60 CIND, and 47 had normal cognition. Median informant age was 70 years (IQR 60 years to 78 years). 71% of informants were female and 56% of informants were spouses.\u003c/p\u003e\n\u003cp\u003eOn all three questionnaires, compared to spouses, adult descendants tended to score participants more cognitively impaired, whereas friends scored participants less cognitively impaired. However, there was little evidence of difference by informant relationship type once fully adjusted.\u003c/p\u003e\n\u003cp\u003eOverall accuracy was similar for all three informant questionnaires with an AUROC of 0.67 (95% CI, 0.62 to 0.72) for IQCODE, 0.64 (95% CI, 0.60 to 0.69) for AD8 and 0.59 (95% CI, 0.56 to 0.63) for GPCOGi. Friends tended to have the highest AUROC at 0.89 (95% CI 0.78 to 1) for IQCODE, 0.88 (95% CI 0.77 to 0.99) for AD8 and 0.69 (95% CI 0.57 to 0.81) for GPCOGi. This difference was significant for IQCODE (p=0.0004) and AD8 (p=0.0001).\u003c/p\u003e\n\u003ch2\u003eConclusions\u003c/h2\u003e\n\u003cp\u003eMost informants were either a spouse or adult descendant. Overall, informants, when using IQCODE, AD8 or GPCOGi may be useful at ruling out dementia but less useful for ruling it in. We found no evidence of difference between spouse or adult descendants but friends (while accounting for only 8% of informants) performed significantly better overall on IQCODE and AD8 due to an increase in specificity without loss of sensitivity.\u003c/p\u003e","manuscriptTitle":"Informant Accuracy of IQCODE, AD8 and GPCOGi for diagnosis of dementia: Does your friend know best?","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-07-19 19:23:56","doi":"10.21203/rs.3.rs-4637777/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2024-06-28T10:28:44+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2024-06-26T08:27:14+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2024-06-26T07:40:54+00:00","index":"","fulltext":""},{"type":"submitted","content":"BMC Primary Care","date":"2024-06-25T16:10:18+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"bmc-primary-care","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"famp","sideBox":"Learn more about [BMC Primary Care](https://bmcprimcare.biomedcentral.com/)","snPcode":"","submissionUrl":"https://author-welcome.nature.com/12875","title":"BMC Primary Care","twitterHandle":"BMC_series","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"f024004d-35ee-463a-aba4-c0b9cfdfed1e","owner":[],"postedDate":"July 19th, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2025-04-21T15:59:20+00:00","versionOfRecord":{"articleIdentity":"rs-4637777","link":"https://doi.org/10.1186/s12875-025-02745-w","journal":{"identity":"bmc-primary-care","isVorOnly":false,"title":"BMC Primary Care"},"publishedOn":"2025-04-15 15:57:11","publishedOnDateReadable":"April 15th, 2025"},"versionCreatedAt":"2024-07-19 19:23:56","video":"","vorDoi":"10.1186/s12875-025-02745-w","vorDoiUrl":"https://doi.org/10.1186/s12875-025-02745-w","workflowStages":[]},"version":"v1","identity":"rs-4637777","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-4637777","identity":"rs-4637777","version":["v1"]},"buildId":"qtupq5eGEP_6zYnWcrvyt","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}