Field Testing of the Psychometric Properties of the Oral Symptom Assessment Scale – Portuguese Version: A Methodological Study

Field Testing of the Psychometric Properties of the Oral Symptom Assessment Scale – Portuguese Version: A Methodological Study | 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 Field Testing of the Psychometric Properties of the Oral Symptom Assessment Scale – Portuguese Version: A Methodological Study Ricardo Serra, Alexandra Barreiros, Ana Mourão, Ana Serra, Gabriela Serra, and 7 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-9393168/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Purpose This study aimed to Translate the Oral Symptom Assessment Scale into Portuguese; and evaluate the construct validity of the Portuguese version of the Oral Symptom Assessment Scale. Methods A methodological, quantitative descriptive, multicentred, cross-sectional study was conducted. The translation, cross-cultural adaptation and construct validity followed COSMIN guidelines. The original instrument was translated to Portuguese, the final translated version was pre-tested in a sample of 30 patients with advanced cancer, locally or metastatically. The final translated version was applied to a sample of 101 patients with advanced cancer, locally or metastatically in an oncology outpatient consultation or receiving hospital palliative care. Three hypothesised structures were analysed with confirmatory factor analysis, following COSMIN guidelines. Results The Portuguese version of the OSAS was well understood, accepted, considered relevant and feasible by the participants. A three-factor model with 17 items was retained with a good overall fit (scaled CFI = 0.979; SRMR = 0.67; RMSEA = 0.60, CI 95% [0.033, 0.082]). No inadmissible parameter estimates were identified in the three factor-model. All factor loadings were statistically significant and within acceptable ranges (from 0.57 to 0.98). Conclusions The three-factor model demonstrated satisfactory model fit, stable parameter estimates, adequate reliability, and acceptable construct validity. Accordingly, we retained the three-factor model as the most appropriate representation of the instrument’s latent structure in this population. The Portuguese version of the OSAS is adequate for research and clinical purposes in Portuguese patients with advanced cancer. Clinical Trial number: Not applicable. Palliative Care Signs and Symptoms Patient Reported Outcome Measures Oral Health Neoplasms 1. INTRODUCTION A symptom reflects changes in the biopsychosocial functioning, sensation, or cognition, it is experienced by the individual and is, therefore, a subjective experience [ 1 ]. Evidence indicates that oral symptoms are frequent in patients with advanced cancer [ 2 ] and in patients with cancer receiving specialist palliative care [ 3 ]. Oral symptoms can be caused by changes in the oral mucosa, due to infections or oral mucositis [ 4 , 5 ], and can be more frequent in patients with progressive disease and impaired functional capacity [ 6 ]. The perception of the symptom by the person experiencing it and their self-report form the basis for the study of symptoms [ 1 ]. It is composed of three interacting concepts: 1) symptom experience; 2) symptom management strategies; 3) outcomes, where the main objective of interest is a change in the symptom status – it’s frequency, severity and distress caused by the symptom [ 1 , 7 ]. At least four validated tools for the assessment of oral symptoms in patients with advanced cancer were identified in published studies [ 8 ]. These include the Memorial Symptom Assessment Scale (MSAS) [ 9 ], the EORTC QLQ-OH17 [ 10 ], the EORTC QLQ-OH15 [ 11 ] and the Oral Symptom Assessment Scale (OSAS) [ 2 ]. The OSAS assesses 20 oral symptoms in their frequency, severity and distress/bothersome [ 2 ]. The OSAS obtained face validity; content validity; and concurrent criterion validity against the Memorial Symptom Assessment Scale – Short Form (MSAS-SF) [ 2 ]. In another study, the OSAS obtained criterion validity against the EORTC QLQ-OH15 [ 12 ]. Instruments to assess the oral symptoms of patients with advanced cancer care are required to perform a rational assessment of the oral symptoms experienced by the patients [ 13 ] and to evaluate the outcomes of oral symptoms management strategies [ 14 ]. To this date, there is no validated instrument to assess multiple oral symptoms in the Portuguese population of patients with advanced cancer. The objectives of this study were to a) Translate the OSAS into Portuguese; b) Assess the construct validity of the Portuguese version of the Oral Symptom Assessment Scale (OSAS-Pt); c) Evaluate the psychometric properties of the OSAS-Pt, in a sample of Portuguese adult patients with advanced cancer in an outpatient oncology consultation; receiving intra-hospital specialist palliative care; or admitted to a palliative care unit. 2. METHODS 2.1. Study design This study followed the COnsensus-based Standards for the selection of health Measurement Instruments (COSMIN) guidelines [ 15 ]. For reporting, the COSMIN guidelines for studies on measurement properties of patient‑reported outcome measures (version 2.0) were followed [ 16 ]. According to COSMIN [ 15 ], the translation process adhered to Beaton et al method [ 17 ]: 1) Translation into Portuguese by two independent translators. Two translations were created. 2) The two translators synthesised their results, producing a single translation. 3) Back-translation into the original language of the instrument by two independent translators, resulting in two back-translations. 4) Analysis of the translations by a committee of experts and creation of a preliminary version. The expert committee was composed of a palliative care specialist nurse with more than 10 years of experience in the field; a palliative care doctor with a PhD and more than 10 years of experience in the field; a nursing professor with a PhD and experience in quantitative research; an oral hygienist professor with a PhD and experience in research; and a linguistic expert. The expert committee analysed the translations and composed a pre-final version that maintained the item’s original meaning. We presented the pre-final version to the authors of the original instrument and they validated it. 5) Pre-testing of the final version of the questionnaire. It is recommended that the final translated version should be tested in a small sample (n = 15–30) of the target population to assess comprehensibility, acceptability and feasibility [ 15 ]. Given the expected physical condition, and frailty, of some of the participants, we opted for the “think out loud” [ 15 ] method to reduce the burden caused by the research on the participants. The following question was asked to 30 participants: “ What is your perception of the oral symptoms questionnaire you have just completed? ”. The dataset was analysed with reflexive thematic analysis, with a deductive approach, in line with COSMIN recommendations [ 18 ]. A methodological, quantitative descriptive, multicentred, cross-sectional study was conducted to assess construct validity and the psychometric properties [ 15 ]. Although exploratory factor analysis (EFA) data from the original authors was available, no confirmatory factor analysis (CFA) results existed or were provided, which are essential to perform a construct validation. Considering that EFA alone cannot confirm model stability [ 19 ]; data on the original CFA is necessary for cross-cultural validation; and that a CFA is the statistical technique that can analyse the stability of the model proposed by an EFA [ 19 ], it’s reliability, convergent validity, and discriminant validity [ 20 ], we proceeded to perform a construct validation. Construct validity was examined through structural validity and hypothesis testing [ 15 , 21 ]. Recommended sample sizes for CFA range from four to ten participants per item, with an absolute minimum of 100 participants and is preferred over EFA when a possible factor structure is already known [ 15 ]. We tested the models proposed by the EFA of the original population and also hypothesized a theory and evidence-based [ 1 – 3 , 22 ] model comprised of three factors with 17 items: changes in oral functions, changes in oral mucosa and dental changes. The OSAS item that screens for symptom presence, was modelled as the basis for frequency scoring to avoid missing data and was analysed as an ordinal scale [ 23 – 25 ]. 2.2. Participants Adult patients, ≥ 18 years old, with a diagnosis of advanced cancer, admitted to a palliative care unit, or in intra-hospital palliative care, or followed in an oncology outpatient consultation, with cognitive capacity to understand and answer the questionnaire, were invited to participate in the study. Data was collected between December 2023 and December 2025. A sample of 30 participants was obtained for the pre-test and a sample of 101 participants was obtained for the cross-cultural validation, both through convenience sampling. 2.3. Data collection The applied data collection instrument consisted of a paper document with three parts: 1) sociodemographic data; 2) capacity for autonomy for activities of daily living; 3) Oral Symptom Assessment Scale. 2.4. Data of the original Oral Symptom Assessment Scale The OSAS is a 20-item questionnaire, which can be considered a reflexive instrument as the underlying construct manifests itself in the items [ 15 ], that asks about the presence of oral symptoms during the past week. The patients are then asked to rate 1) the frequency of each oral symptom as “rarely”, “occasionally”, “frequently”, “almost constantly”; 2) the severity of each oral symptom as “slight”, “moderate”, “severe”, “very severe”; 3) the distressed/bothersome caused by each oral symptom as “not at all”, “a little bit”, “somewhat”, “quite a bit”, “very much” [ 2 ]. The EFA, conducted by the authors of the original version, demonstrated two possible factor structures (data provided upon request). A five factors model, based on the prevalence of the symptom (a nominal and dichotomic variable), as the optimal solution. Another possible optimal solution, based in the symptoms’ frequency, also produced a 5 factors mode. In both models, the authors considered only 14 symptoms with a prevalence of > 15%. 2.5. Statistical analysis We performed all statistical analysis in Jamovi® version 2.7.17. To assess the model fit, we used the comparative fit index (CFI), the root mean square error of approximation (RMSEA) and the standardized root mean square residual (SRMR) in both models identified by the original authors of the OSAS. Chi-square tests can lead to rejection of good fitting models, due to their high sensitivity to sample size, and were not reported [ 15 ]. All models were estimated in a sample of 101 participants using diagonally weighted least squares (DWLS) with robust standard errors and a mean-adjusted scaled and shifted test statistic, based on a polychoric correlation matrix of ordered ordinal indicators [ 24 – 26 ]. Models with a CFI > 0.90 represent an acceptable fit; a CFI > 0.95 represents a good fit; a RMSEA 0.10 represents a poor fit; a SRMR < 0.08 represents a good fit. Parsimony Normed Fit Index (PNFI) closer to 1 are indicative of a better fit. The internal consistency was assessed using Cronbach’s Alpha coefficient a value of 0.7 ≤ α < 0.8: Acceptable; 0.8 ≤ α < 0.9: Good; ≥0.9: Excellent. The Composite Reliability (CR) was measured to assess the internal consistency of a set of latent construct indicators, CR ≥ 0.70: Indicates adequate reliability; CR ≥ 0.80: Indicates good reliability; CR ≥ 0.90: Indicates excellent reliability. Average Variance Extracted (AVE) was measured to assess the amount of variance captured by a latent construct in relation to the amount of variance due to measurement error, with an acceptable threshold of 0.50 in which 50% of the variance of the indicators should be accounted for by the latent variable [ 20 ]. 3. ETHICAL CONSIDERATIONS The study was part of a broader project to develop an oral symptom management strategy for terminally ill patients with cancer in palliative care. Prior authorisation to use the original OSAS was obtained from its authors. The research followed the MORECare Statement, which provides guidance for conducting ethically sound complex intervention research in palliative care [ 27 ]. Responsibility for communicating diagnostic and prognostic information remained with the clinical team, who should disclose such information at the patients request and pace [ 28 ]. Although the patients had previous knowledge of their diagnosis, we did not explicitly reveal cancer diagnoses or prognostic details. Instead, participants were informed that the research aimed to validate a tool for assessing oral symptoms, and inclusion criteria were described without reference to specific diseases or prognoses. The study received ethical approval from the ethics committee and the administrative boards of all participating institutions. Written free and informed consent was obtained from all participants. 4. RESULTS 4.1. Translation and analysis by the experts committee The experts committee compared the original English version, the translated versions, the back translated version and the Portuguese synthesis version, to ensure that semantic, idiomatic, experiential and conceptual equivalence were present in the pre-test version. The experts committee, upon analysis and discussion reached consensus and considered that the OSAS-Pt (Additional file 1) was adequate to be understood by the equivalent of a 12-year-old (approximately a grade six level of reading) and that the pre-final version was ready to be tested [ 17 ]. We presented the pre-final version to the original authors, and after they validated it, we proceeded with the pilot test. 4.2. Pilot testing The comprehensibility, relevance, acceptability, and feasibility by the participants was assessed with a reflexive thematic analysis, following a deductive approach, of the participants answers to the question “ What is your perception of the oral symptoms questionnaire you have just completed?” . 30 participants with a mean age of 65,9 years of age and a median age of 67, ranging from 45 to 86 years of age, participated in the pilot test. Eight participants had a primary education level; 10 participants had a second level of primary education; four participants had a third level of primary education; two participants had a secondary education; six participants had higher education. Overall, participants found the OSAS-Pt easy to understand and to complete, suggesting face validity and linguistic clarity [ 15 ]. Only one item (Coating of tongue) was reported by some participants to not be more difficult to understand ( Língua saborrosa ). The OSAS-Pt was found relevant, and feasible, by the participants and was well accepted; however, some participants thought the questionnaire was too long felt tired after completing. 4.3. Psychometric properties analysis 4.3.1. Participants’ characteristics 101 participants were recruited and completed the study. Participants characteristics are presented in Table 1 . Participants were 52 male (51.5%) and 49 female (48.5%). The mean age was 66.9 years old, the median age was 68, the participants’ age ranged from 30 to 91 years of age. The majority of participants had a level of first cycle of primary education (n = 38; 37.6%), followed by those with a second level of primary education (n = 19; 18.8%) and secondary education (n = 19; 18.8%). Those with the third level of primary education and higher education were 12 each (11.9%). Only one participant reported not knowing how to write or read (1.0%). The sample studied is characterized by a low to medium level of education and a relevant proportion of participants with primary education level. Most participants were classified as independent for ADL (n = 52; 52.3%), 37 participants were classified as highly dependent for ADL (36.6%), and 11 participants were classified has having a moderate dependence for ADL (10.9%). The sample studied was composed of mostly older adults with a low to medium level of education, a relevant portion of the participants presented some level of dependence for ADL and metastatic cancer. Table 1 Descriptive characteristics of the sample. Variable Category / Statistic n (%) / Value Age (years) Mean (SD) 66.9 (12.7) Median 68 Mode 67 Range 30–91 95% CI for the mean [64.4, 69.4] Sex Male 52 (51.5%) Female 49 (48.5%) Marital status Single 12 (11.9%) Married 57 (56.4%) Widowed 15 (14.9%) Divorced 11 (10.9%) Cohabiting (civil partnership) 6 (5.9%) Educational level Illiterate 1 (1.0%) Primary education 38 (37.6%) Second level of primary education 19 (18.8%) Third level of primary education 12 (11.9%) Secondary education 19 (18.8%) Higher education 12 (11.9%) Independence for ADL Independent 53 (52.5%) Moderately dependent 11 (10.9%) Highly dependent 37 (36.6%) Note. Percentages are based on valid responses. 4.3.2. Reliability We assessed the internal consistency of the OSAS-Pt using Cronbach’s α and McDonald’s ω coefficient, of the 20 items (prevalence and frequency); of the 15 and 14 items identified in the original factor structure (prevalence and frequency); and of the 17 items that comprise the 3-factor model. For the results based on the prevalence of 20 items, Cronbach’s α = 0.901 and McDonald’s ω = 0.901. Based on the frequency of 20 items, Cronbach’s α = 0.908 and McDonald’s ω = 0.912. Both Cronbach’s α values are indicative of excellent internal consistency [ 20 , 29 ]. Both McDonald’s ω are indicative of an excellent internal consistency [ 30 , 31 ]. For the results based on the prevalence of the 14 items of the original factor structure, Cronbach’s α = 0.878 and McDonald’s ω = 0.880. For the results based on the frequency of the 14 items of the original factor structure, Cronbach’s α = 0.882 and McDonald’s ω = 0.887. Both Cronbach’s α values are indicative of good internal consistency [ 20 , 29 ]. Both McDonald’s ω are indicative of good internal consistency [ 30 , 31 ]. For the results based on the prevalence of the 17 items of the three-factor structure, Cronbach’s α = 0.896 and McDonald’s ω = 0.897. For the results based on the frequency of the 17 items of the three-factor structure, Cronbach’s α = 0.905 and McDonald’s ω = 0.907. Both Cronbach’s α values are indicative of good internal consistency [ 20 , 29 ]. Both McDonald’s ω are indicative of good internal consistency [ 30 , 31 ]. 4.3.3. Construct validity - Confirmatory factor analysis We conducted a CFA to test the prevalence based five-factor structure identified in the original EFA (Additional file 2), which included five latent factors and 14 items that assessed the symptoms prevalence: Factor 1 (Coating of tongue, dirty mouth, taste disturbance, bad breath); Factor 2 (Lip discomfort, Difficulty speaking, Difficulty chewing, Difficulty swallowing); Factor 3 (Mouth discomfort, Ulcers in mouth); Factor 4 (jagged teeth, sensivity of teeth); Factor 5 (cracking of lips, cracking of corners of mouth). Overall model fit results indicate a very good fit (scaled CFI = 0.985; SRMR = 0.085; RMSEA = 0.045 95% CI [0.000, 0.077]). The observed Parsimony Normed Fit Index (PNFI) was 0.697. A very high loading for item15_freq of 1.288, as well as a negative variance for that item ( \(\:\beta\:=\:-0.659\) ). Negative variances are indicative of improper solutions and local model misspecification. A model with inadmissible parameter estimates cannot be considered psychometrical sound, regardless of global fit statistics [ 32 ]. Therefore, this model was not retained. We conducted another CFA to test the original frequency-based five-factor structure identified in the original EFA (Additional file 3). This model included five latent factors and 14 items that assessed the symptoms frequency: Factor 1 (Items 7; 8; 9), Factor 2 (items 6; 10; 11; 12), Factor 3 (items 2; 20), Factor 4 (items 3; 4; 5) and Factor 5 (items 14; 15). The scaled results indicate a good model fit with SRMR = 0.058, RMSEA = 0.065 (95% CI [0.030, 0.093] p =.209). The observed PNFI was 0.688. A very high loading for item15_freq exceeding 1.90, as well as a negative variance for that item ( \(\:\beta\:=\:-0.279\) ). Negative variances and improper solutions indicate local model misspecification. We also observed some very high latent factor correlations (approaching 0.90). These results are suggestive of overlapping latent variables. A model with inadmissible parameter estimates cannot be considered psychometrical sound, regardless of global fit statistics [ 32 ]. Therefore, this model was not retained. Considering the instability of the five factor models, a theoretically informed three-factor model was tested (Additional file 4). This model comprised 17 items distributed across three correlated latent variables. The three-factor model demonstrated good overall fit (scaled CFI = 0.979; SRMR = 0.67; RMSEA = 0.60, CI 95% [0.033, 0.082]). The observed PNFI was 0.790. No inadmissible parameter estimates were identified. All factor loadings were statistically significant and within acceptable ranges (from 0.57 to 0.98). No negative residual variances or loadings greater than 1.00 were observed. The latent covariance matrix was positive definite, and the inter-factor correlations did not exceed 0.90. Reliability estimates were acceptable to good. Cronbach’s α ranged from 0.738 (Factor 3) to 0.896 (Factor 2). Ordinal α ranged from 0.850 (Factor 1) to 0.936 (Factor2). Composite reliability indices ω₁, ω₂, ω₃, ranged from 0.786 to 0.936. AVE for Factor1 was 0.612; for Factor 2 was 0.622; for Factor3 was 0.741, all values indicative of adequate convergent validity. Thus, the three-factor model was retained. 5. DISCUSSION This study presents, to our knowledge, the first multi-symptom oral assessment instrument validated for Portuguese patients with advanced cancer. The use of inappropriate tools to assess oral symptoms hinders the evaluation of oral symptom management strategies [ 14 ]; therefore, validated instruments for assessing oral symptoms are essential to examine the effectiveness of interventions to manage oral symptoms in both research and clinical practice [ 2 , 14 ]. Some participants stated that some items may not apply to all patients (e.g., denture-fitting problems). Excessively long instruments may hinder clinical feasibility for both professionals and patients [ 33 ] and fatigue is known to have a detrimental effect on quality of life of patients with advanced cancer [ 34 ]. Although the CFA did not reveal issues with the item “Coating of tongue”, some participants found it difficult to understand. User feedback is essential in instrument development [ 15 ]; therefore, future studies could develop a shorter version to minimize patient burden, modelled after the MSAS short form [ 2 , 35 ], as proposed by the original authors [ 2 ]; adopt less clinical terms to enhance comprehensibility [ 15 ]; and clarify that certain items may be non-applicable. An EFA cannot assess factor stability or detect inadmissible solutions [ 19 ], such as Heywood cases [ 36 ], which are only identified with a CFA [ 19 , 36 ]. Heywood cases, as those identified in the five-factors models, are often the result of a structure misspecification [ 37 ]. Both five-factors models had acceptable global fit indices [ 15 ]. However, they presented inadmissible solutions and structural instability, such as Heywood cases [ 36 , 38 ] and high inter-factor correlations that compromised construct distinction [ 32 ]. Construct validation requires testing alternative models informed by theory and empirical evidence [ 15 , 32 ]. Guided by the Symptom Management Theory, empirical evidence, and the data derived from the five-factor structure models, we tested a three-factor model, which demonstrated good fit, statistical stability, and greater parsimony with a higher PNFI [ 20 ]. The three-factor model comprises 17 items, that assess symptom frequency loaded into three factors: Factor 1 – “ Changes in oral functions” (items: Taste disturbance; Difficulty chewing; Difficulty swallowing; Difficulty speaking – items 6–9, respectively). Factor 2 – “Changes in oral mucosa” , (items: Dry mouth; Mouth discomfort/pain; Lip discomfort; Cracking of lips; Cracking of corners of mouth; “Dirty” mouth; Coating of tongue; Bad breath; Burning sensation in mouth; Altered sensation in mouth – items 1–5; 10–12; 18, 19 respectively). Factor 3 – “ Dental changes” (items – Toothache/pain in teeth; Sensitivity of teeth; Jagged teeth – items 13–15, respectively). Two items did not fit the factor structure as they can be considered signs: Bleeding from the mouth and Ulcers in mouth (items 17 and 20, respectively). The item Denture fitting problems (item 16) also did not fit the model structure, as it is not applicable to all the possible patients that the instrument was developed for. Although these items do not load into any of the identified factors, they remain clinically relevant to assess oral problems in patients with advanced cancer [ 3 , 11 ], therefore we decided to maintain these items in the OSAS-Pt. 5.1. Limitations The absence of data from the original OSAS population did not allow for cross-cultural validation, restricting the study to construct validation. Responsiveness [ 33 ] was not assessed, as this would require a longitudinal study and repeated patient participation, which was considered ethically inappropriate given the expected population’s frailty and uncertainty regarding the validation of the translated version. As instrument development is iterative [ 15 ], future studies should examine responsiveness of the OSAS-Pt. Although item 6 (Coating of tongue) was statistically adequate, reported comprehension difficulties warrant reconsideration of its translation in future research. 6. CONCLUSIONS The OSAS-Pt was well understood, accepted, considered relevant and feasible by the participants of this study. The five-factor structures were not psychometrically supported due to inadmissible parameter estimates and structural instability. The three-factor model demonstrated satisfactory model fit, stable parameter estimates, adequate reliability, and acceptable construct validity. Accordingly, we retained the three-factor model as the most appropriate representation of the instrument’s latent structure in this population. The OSAS-Pt is a psychometrically robust and culturally appropriate instrument to assess oral symptoms in Portuguese patients with advanced cancer. Future studies can further confirm the identified factor-structure in other populations, revise the items that are less comprehensible, investigate the OSAS-Pt responsiveness, and develop a short-form OSAS-Pt more adequate to clinical practice. Declarations Ethics approval This study was performed in line with the principles of the Declaration of Helsinki. Ethical approval was obtained from the Ethics Committee of all involved institutions: Administração Regional de Saúde do Alentejo (15/CE/2023); Instituto São João de Deus (Ethics Committee approval on the 31st of March 2023); Unidade Local de Saúde do Litoral Alentejano (E/5635/23/CA); Unidade Local de Saúde do Norte Alentejano (13/2023); Unidade Local de Saúde do Algarve (on the 4th of March 2024). Funding The authors declare that no funds, grants, or other support were received during the preparation of this manuscript. Author Contribution Ricardo Serra and Helena Arco contributed to the study conception and design. Data collection was performed by Alexandra Barreiros, Ana Mourão, Ana Serra, Gabriela Serra, Rita Lourenço, Rosário Neto, Sofia Coito, and Vânia Cunha. Material preparation and analysis were performed by Ricardo Serra, Adelaide Proença, Andreia Costa and Helena Arco. The first draft of the manuscript was written by Ricardo Serra and all authors commented on previous versions of the manuscript. All authors read and approved the final manuscript. Acknowledgement We would like to thank Dr. Andrew Davies and colleagues, for developing the OSAS and granting authorization to translate and validate it in the Portuguese population, as well as all the staff that cooperated at the study sites: Unidade Local de Saúde do Alto Alentejo (Oncology Service and Palliative care Unit); Unidade Local de Saúde do Litoral Alentejano (Palliative Care Unit); Unidade Local de Saúde do Alentejo Central (Intra-Hospital Palliative Care Support Team); Unidade Local de Saúde do Algarve (Palliative Care Unit); Instituto São João de Deus, Hospital de Montemor (Palliative Care Unit). RS is a nursing PhD student at Lisbon Nursing School of the University of Lisbon; this study forms part of his doctoral thesis. 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[cited 2026 Jan 16];24:561–77. https://doi.org/10.9734/ajeba/2024/v24i71430 Mokkink LB, Terwee CB, Patrick DL, Alonso J, Stratford PW, Knol DL et al (2010) The COSMIN study reached international consensus on taxonomy, terminology, and definitions of measurement properties for health-related patient-reported outcomes. J Clin Epidemiol [Internet] 63:737–745. https://doi.org/10.1016/j.jclinepi.2010.02.006 Walsh M, Fagan N, Davies A (2023) Xerostomia in patients with advanced cancer: a scoping review of clinical features and complications. BMC Palliat Care [Internet] BioMed Cent Ltd 22:178. https://doi.org/10.1186/s12904-023-01276-4 Liu Y, Verkuilen J (2013) Item Response Modeling of Presence-Severity Items. Appl Psychol Meas [Internet] 37:58–75 [cited 2026 Feb 19];. https://doi.org/10.1177/0146621612455091 Marôco J (2024) Factor Analysis of Ordinal Items: Old Questions, Modern Solutions? Stats (Basel). Multidisciplinary Digital Publishing Institute (MDPI); ;7:984–1001. https://doi.org/10.3390/stats7030060 Robitzsch A (2022) On the Bias in Confirmatory Factor Analysis When Treating Discrete Variables as Ordinal Instead of Continuous. Axioms MDPI 11. https://doi.org/10.3390/axioms11040162 Park CG (2024) Implementing alternative estimation methods to evaluate the reliability of Likert-scale instruments. Womens Health Nurs [Internet] 30:18–25 [cited 2026 Feb 14];. https://doi.org/10.4069/whn.2024.03.12 Higginson IJ, Evans CJ, Grande G, Preston N, Morgan M, Mccrone P et al (2013) Evaluating complex interventions in End of Life Care: the MORECare Statement on good practice generated by a synthesis of transparent expert consultations and systematic reviews [Internet]. http://www.biomedcentral.com/1741-7015/11/111 van der Velden NCA, Meijers MC, Han PKJ, van Laarhoven HWM, Smets EMA, Henselmans I (2020) The Effect of Prognostic Communication on Patient Outcomes in Palliative Cancer Care: a Systematic Review. Curr Treat Options Oncol [Internet] 21:40. https://doi.org/10.1007/s11864-020-00742-y Cronbach LJ, COEFFICIENT ALPHA AND, THE INTERNAL STRUCTURE OF TESTS* (1951) Psychometrika 16:297–334 Zhang Z, Yuan KH (2016) Robust Coefficients Alpha and Omega and Confidence Intervals With Outlying Observations and Missing Data: Methods and Software. Educ Psychol Meas [Internet]. SAGE Publications Inc.; [cited 2026 Feb 11];76:387–411. https://doi.org/10.1177/0013164415594658 Kalkbrenner MT (2024) Choosing Between Cronbach’s Coefficient Alpha, McDonald’s Coefficient Omega, and Coefficient H: Confidence Intervals and the Advantages and Drawbacks of Interpretive Guidelines. Measurement and Evaluation in Counseling and Development [Internet]. [cited 2026 Feb 11];57:93–105. https://doi.org/10.1080/07481756.2023.2283637 Alavi M, Biros E, Cleary M (2024) Notes to Factor Analysis Techniques for Construct Validity. Canadian Journal of Nursing Research, vol 56. SAGE Publications Inc., pp 164–170. https://doi.org/10.1177/08445621231204296 Reeve BB, Wyrwich KW, Wu AW, Velikova G, Terwee CB, Snyder CF et al (2013) ISOQOL recommends minimum standards for patient-reported outcome measures used in patient-centered outcomes and comparative effectiveness research. Qual Life Res 22:1889–1905. https://doi.org/10.1007/s11136-012-0344-y Curt GA (2000) The Impact of Fatigue on Patients with Cancer. Overview of FATIGUE 1 and 2. Oncologist, vol 5. Oxford University Press (OUP), pp 9–12. https://doi.org/10.1634/theoncologist.5-suppl_2-9 Chang VT, Hwang SS, Feuerman M, Kasimis BS, Thaler HT The Memorial Symptom Assessment Scale Short Form (MSAS-SF). Cancer [Internet]. 2000 [cited 2026 Feb 18];89:1162–71. https://doi.org/10.1002/1097-0142(20000901)89:5%3C1162::AID-CNCR26%3E3.0.CO;2-Y Verkuilen J, Johnson PJ (2024) A Definition of a Heywood Case in Item Response Theory Based on Fisher Information. Entropy. Multidisciplinary Digital Publishing Institute (MDPI), p 26. https://doi.org/10.3390/e26121096 Kolenikov S, Bollen KA (2012) Testing Negative Error Variances: Is a Heywood Case a Symptom of Misspecification? Sociol Methods Res 40:124–167. https://doi.org/10.1177/0049124112442138 Karstoft KI, Vindbjerg E, Nielsen ABS, Andersen SB, Folke S (2025) The factor structure of the International Trauma Questionnaire–Heywood cases in confirmatory factor analysis. Eur J Psychotraumatol Taylor Francis Ltd 16. https://doi.org/10.1080/20008066.2024.2444745 Additional Declarations No competing interests reported. Supplementary Files AF1OSASPt.pdf AF2Original5f14sinprev.pdf AF4CFA3f17sint.pdf AF3Original5f14sinfreq.pdf Cite Share Download PDF Status: Posted Version 1 posted 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. 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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-9393168","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":623840185,"identity":"4249488b-e5cc-496d-9349-f2412c590abe","order_by":0,"name":"Ricardo 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INTRODUCTION","content":"\u003cp\u003eA symptom reflects changes in the biopsychosocial functioning, sensation, or cognition, it is experienced by the individual and is, therefore, a subjective experience [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]. Evidence indicates that oral symptoms are frequent in patients with advanced cancer [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e] and in patients with cancer receiving specialist palliative care [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]. Oral symptoms can be caused by changes in the oral mucosa, due to infections or oral mucositis [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e, \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e], and can be more frequent in patients with progressive disease and impaired functional capacity [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eThe perception of the symptom by the person experiencing it and their self-report form the basis for the study of symptoms [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]. It is composed of three interacting concepts: 1) symptom experience; 2) symptom management strategies; 3) outcomes, where the main objective of interest is a change in the symptom status \u0026ndash; it\u0026rsquo;s frequency, severity and distress caused by the symptom [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e, \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eAt least four validated tools for the assessment of oral symptoms in patients with advanced cancer were identified in published studies [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]. These include the Memorial Symptom Assessment Scale (MSAS) [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e], the EORTC QLQ-OH17 [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e], the EORTC QLQ-OH15 [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e] and the Oral Symptom Assessment Scale (OSAS) [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eThe OSAS assesses 20 oral symptoms in their frequency, severity and distress/bothersome [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]. The OSAS obtained face validity; content validity; and concurrent criterion validity against the Memorial Symptom Assessment Scale \u0026ndash; Short Form (MSAS-SF) [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]. In another study, the OSAS obtained criterion validity against the EORTC QLQ-OH15 [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]. Instruments to assess the oral symptoms of patients with advanced cancer care are required to perform a rational assessment of the oral symptoms experienced by the patients [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e] and to evaluate the outcomes of oral symptoms management strategies [\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e]. To this date, there is no validated instrument to assess multiple oral symptoms in the Portuguese population of patients with advanced cancer.\u003c/p\u003e \u003cp\u003e The objectives of this study were to a) Translate the OSAS into Portuguese; b) Assess the construct validity of the Portuguese version of the Oral Symptom Assessment Scale (OSAS-Pt); c) Evaluate the psychometric properties of the OSAS-Pt, in a sample of Portuguese adult patients with advanced cancer in an outpatient oncology consultation; receiving intra-hospital specialist palliative care; or admitted to a palliative care unit.\u003c/p\u003e"},{"header":"2. METHODS","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003e2.1. Study design\u003c/h2\u003e \u003cp\u003eThis study followed the COnsensus-based Standards for the selection of health Measurement Instruments (COSMIN) guidelines [\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e]. For reporting, the COSMIN guidelines for studies on measurement properties of patient‑reported outcome measures (version 2.0) were followed [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eAccording to COSMIN [\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e], the translation process adhered to Beaton et al method [\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e]: 1) Translation into Portuguese by two independent translators. Two translations were created. 2) The two translators synthesised their results, producing a single translation. 3) Back-translation into the original language of the instrument by two independent translators, resulting in two back-translations. 4) Analysis of the translations by a committee of experts and creation of a preliminary version. The expert committee was composed of a palliative care specialist nurse with more than 10 years of experience in the field; a palliative care doctor with a PhD and more than 10 years of experience in the field; a nursing professor with a PhD and experience in quantitative research; an oral hygienist professor with a PhD and experience in research; and a linguistic expert. The expert committee analysed the translations and composed a pre-final version that maintained the item\u0026rsquo;s original meaning. We presented the pre-final version to the authors of the original instrument and they validated it. 5) Pre-testing of the final version of the questionnaire. It is recommended that the final translated version should be tested in a small sample (n\u0026thinsp;=\u0026thinsp;15\u0026ndash;30) of the target population to assess comprehensibility, acceptability and feasibility [\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e]. Given the expected physical condition, and frailty, of some of the participants, we opted for the \u0026ldquo;think out loud\u0026rdquo; [\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e] method to reduce the burden caused by the research on the participants. The following question was asked to 30 participants: \u0026ldquo;\u003cem\u003eWhat is your perception of the oral symptoms questionnaire you have just completed?\u003c/em\u003e\u0026rdquo;. The dataset was analysed with reflexive thematic analysis, with a deductive approach, in line with COSMIN recommendations [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eA methodological, quantitative descriptive, multicentred, cross-sectional study was conducted to assess construct validity and the psychometric properties [\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eAlthough exploratory factor analysis (EFA) data from the original authors was available, no confirmatory factor analysis (CFA) results existed or were provided, which are essential to perform a construct validation. Considering that EFA alone cannot confirm model stability [\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e]; data on the original CFA is necessary for cross-cultural validation; and that a CFA is the statistical technique that can analyse the stability of the model proposed by an EFA [\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e], it\u0026rsquo;s reliability, convergent validity, and discriminant validity [\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e], we proceeded to perform a construct validation.\u003c/p\u003e \u003cp\u003eConstruct validity was examined through structural validity and hypothesis testing [\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e, \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e]. Recommended sample sizes for CFA range from four to ten participants per item, with an absolute minimum of 100 participants and is preferred over EFA when a possible factor structure is already known [\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e]. We tested the models proposed by the EFA of the original population and also hypothesized a theory and evidence-based [\u003cspan additionalcitationids=\"CR2\" citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e, \u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e] model comprised of three factors with 17 items: changes in oral functions, changes in oral mucosa and dental changes. The OSAS item that screens for symptom presence, was modelled as the basis for frequency scoring to avoid missing data and was analysed as an ordinal scale [\u003cspan additionalcitationids=\"CR24\" citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e].\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec4\" class=\"Section2\"\u003e \u003ch2\u003e2.2. Participants\u003c/h2\u003e \u003cp\u003eAdult patients, \u0026ge;\u0026thinsp;18 years old, with a diagnosis of advanced cancer, admitted to a palliative care unit, or in intra-hospital palliative care, or followed in an oncology outpatient consultation, with cognitive capacity to understand and answer the questionnaire, were invited to participate in the study. Data was collected between December 2023 and December 2025. A sample of 30 participants was obtained for the pre-test and a sample of 101 participants was obtained for the cross-cultural validation, both through convenience sampling.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec5\" class=\"Section2\"\u003e \u003ch2\u003e2.3. Data collection\u003c/h2\u003e \u003cp\u003eThe applied data collection instrument consisted of a paper document with three parts: 1) sociodemographic data; 2) capacity for autonomy for activities of daily living; 3) Oral Symptom Assessment Scale.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec6\" class=\"Section2\"\u003e \u003ch2\u003e2.4. Data of the original Oral Symptom Assessment Scale\u003c/h2\u003e \u003cp\u003eThe OSAS is a 20-item questionnaire, which can be considered a reflexive instrument as the underlying construct manifests itself in the items [\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e], that asks about the presence of oral symptoms during the past week. The patients are then asked to rate 1) the frequency of each oral symptom as \u0026ldquo;rarely\u0026rdquo;, \u0026ldquo;occasionally\u0026rdquo;, \u0026ldquo;frequently\u0026rdquo;, \u0026ldquo;almost constantly\u0026rdquo;; 2) the severity of each oral symptom as \u0026ldquo;slight\u0026rdquo;, \u0026ldquo;moderate\u0026rdquo;, \u0026ldquo;severe\u0026rdquo;, \u0026ldquo;very severe\u0026rdquo;; 3) the distressed/bothersome caused by each oral symptom as \u0026ldquo;not at all\u0026rdquo;, \u0026ldquo;a little bit\u0026rdquo;, \u0026ldquo;somewhat\u0026rdquo;, \u0026ldquo;quite a bit\u0026rdquo;, \u0026ldquo;very much\u0026rdquo; [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]. The EFA, conducted by the authors of the original version, demonstrated two possible factor structures (data provided upon request). A five factors model, based on the prevalence of the symptom (a nominal and dichotomic variable), as the optimal solution. Another possible optimal solution, based in the symptoms\u0026rsquo; frequency, also produced a 5 factors mode. In both models, the authors considered only 14 symptoms with a prevalence of \u0026gt;\u0026thinsp;15%.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec7\" class=\"Section2\"\u003e \u003ch2\u003e2.5. Statistical analysis\u003c/h2\u003e \u003cp\u003eWe performed all statistical analysis in Jamovi\u0026reg; version 2.7.17. To assess the model fit, we used the comparative fit index (CFI), the root mean square error of approximation (RMSEA) and the standardized root mean square residual (SRMR) in both models identified by the original authors of the OSAS. Chi-square tests can lead to rejection of good fitting models, due to their high sensitivity to sample size, and were not reported [\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e]. All models were estimated in a sample of 101 participants using diagonally weighted least squares (DWLS) with robust standard errors and a mean-adjusted scaled and shifted test statistic, based on a polychoric correlation matrix of ordered ordinal indicators [\u003cspan additionalcitationids=\"CR25\" citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eModels with a CFI\u0026thinsp;\u0026gt;\u0026thinsp;0.90 represent an acceptable fit; a CFI\u0026thinsp;\u0026gt;\u0026thinsp;0.95 represents a good fit; a RMSEA\u0026thinsp;\u0026lt;\u0026thinsp;0.05 represents a good fit, a 0.05\u0026ndash;0.08 represents an acceptable fit, \u0026gt;\u0026thinsp;0.10 represents a poor fit; a SRMR\u0026thinsp;\u0026lt;\u0026thinsp;0.08 represents a good fit. Parsimony Normed Fit Index (PNFI) closer to 1 are indicative of a better fit. The internal consistency was assessed using Cronbach\u0026rsquo;s Alpha coefficient a value of 0.7\u0026thinsp;\u0026le;\u0026thinsp;α\u0026thinsp;\u0026lt;\u0026thinsp;0.8: Acceptable; 0.8\u0026thinsp;\u0026le;\u0026thinsp;α\u0026thinsp;\u0026lt;\u0026thinsp;0.9: Good; \u0026ge;0.9: Excellent. The Composite Reliability (CR) was measured to assess the internal consistency of a set of latent construct indicators, CR\u0026thinsp;\u0026ge;\u0026thinsp;0.70: Indicates adequate reliability; CR\u0026thinsp;\u0026ge;\u0026thinsp;0.80: Indicates good reliability; CR\u0026thinsp;\u0026ge;\u0026thinsp;0.90: Indicates excellent reliability. Average Variance Extracted (AVE) was measured to assess the amount of variance captured by a latent construct in relation to the amount of variance due to measurement error, with an acceptable threshold of 0.50 in which 50% of the variance of the indicators should be accounted for by the latent variable [\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e].\u003c/p\u003e \u003c/div\u003e"},{"header":"3. ETHICAL CONSIDERATIONS","content":"\u003cp\u003eThe study was part of a broader project to develop an oral symptom management strategy for terminally ill patients with cancer in palliative care. Prior authorisation to use the original OSAS was obtained from its authors. The research followed the MORECare Statement, which provides guidance for conducting ethically sound complex intervention research in palliative care [\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e]. Responsibility for communicating diagnostic and prognostic information remained with the clinical team, who should disclose such information at the patients request and pace [\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e]. Although the patients had previous knowledge of their diagnosis, we did not explicitly reveal cancer diagnoses or prognostic details. Instead, participants were informed that the research aimed to validate a tool for assessing oral symptoms, and inclusion criteria were described without reference to specific diseases or prognoses.\u003c/p\u003e \u003cp\u003e The study received ethical approval from the ethics committee and the administrative boards of all participating institutions. Written free and informed consent was obtained from all participants.\u003c/p\u003e"},{"header":"4. RESULTS","content":"\u003cdiv id=\"Sec10\" class=\"Section2\"\u003e \u003ch2\u003e4.1. Translation and analysis by the experts committee\u003c/h2\u003e \u003cp\u003eThe experts committee compared the original English version, the translated versions, the back translated version and the Portuguese synthesis version, to ensure that semantic, idiomatic, experiential and conceptual equivalence were present in the pre-test version. The experts committee, upon analysis and discussion reached consensus and considered that the OSAS-Pt (Additional file 1) was adequate to be understood by the equivalent of a 12-year-old (approximately a grade six level of reading) and that the pre-final version was ready to be tested [\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e]. We presented the pre-final version to the original authors, and after they validated it, we proceeded with the pilot test.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec11\" class=\"Section2\"\u003e \u003ch2\u003e4.2. Pilot testing\u003c/h2\u003e \u003cp\u003eThe comprehensibility, relevance, acceptability, and feasibility by the participants was assessed with a reflexive thematic analysis, following a deductive approach, of the participants answers to the question \u0026ldquo;\u003cem\u003eWhat is your perception of the oral symptoms questionnaire you have just completed?\u0026rdquo;\u003c/em\u003e. 30 participants with a mean age of 65,9 years of age and a median age of 67, ranging from 45 to 86 years of age, participated in the pilot test. Eight participants had a primary education level; 10 participants had a second level of primary education; four participants had a third level of primary education; two participants had a secondary education; six participants had higher education.\u003c/p\u003e \u003cp\u003eOverall, participants found the OSAS-Pt easy to understand and to complete, suggesting face validity and linguistic clarity [\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e]. Only one item (Coating of tongue) was reported by some participants to not be more difficult to understand (\u003cem\u003eL\u0026iacute;ngua saborrosa\u003c/em\u003e). The OSAS-Pt was found relevant, and feasible, by the participants and was well accepted; however, some participants thought the questionnaire was too long felt tired after completing.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec12\" class=\"Section2\"\u003e \u003ch2\u003e4.3. Psychometric properties analysis\u003c/h2\u003e \u003cdiv id=\"Sec13\" class=\"Section3\"\u003e \u003ch2\u003e4.3.1. Participants\u0026rsquo; characteristics\u003c/h2\u003e \u003cp\u003e101 participants were recruited and completed the study. Participants characteristics are presented in Table \u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e. Participants were 52 male (51.5%) and 49 female (48.5%). The mean age was 66.9 years old, the median age was 68, the participants\u0026rsquo; age ranged from 30 to 91 years of age.\u003c/p\u003e \u003cp\u003eThe majority of participants had a level of first cycle of primary education (n\u0026thinsp;=\u0026thinsp;38; 37.6%), followed by those with a second level of primary education (n\u0026thinsp;=\u0026thinsp;19; 18.8%) and secondary education (n\u0026thinsp;=\u0026thinsp;19; 18.8%). Those with the third level of primary education and higher education were 12 each (11.9%). Only one participant reported not knowing how to write or read (1.0%). The sample studied is characterized by a low to medium level of education and a relevant proportion of participants with primary education level.\u003c/p\u003e \u003cp\u003eMost participants were classified as independent for ADL (n\u0026thinsp;=\u0026thinsp;52; 52.3%), 37 participants were classified as highly dependent for ADL (36.6%), and 11 participants were classified has having a moderate dependence for ADL (10.9%).\u003c/p\u003e \u003cp\u003e The sample studied was composed of mostly older adults with a low to medium level of education, a relevant portion of the participants presented some level of dependence for ADL and metastatic cancer.\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\u003eDescriptive characteristics of the sample.\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 \u003cp\u003eVariable\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e \u003cp\u003eCategory / Statistic\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003en (%) / Value\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"4\" rowspan=\"5\"\u003e \u003cp\u003eAge (years)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e \u003cp\u003eMean (SD)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e66.9 (12.7)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e \u003cp\u003eMedian\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e68\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e \u003cp\u003eMode\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e67\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e \u003cp\u003eRange\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e30\u0026ndash;91\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e \u003cp\u003e95% CI for the mean\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e[64.4, 69.4]\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eSex\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e \u003cp\u003eMale\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e52 (51.5%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e \u003cp\u003eFemale\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e49 (48.5%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"4\" rowspan=\"5\"\u003e \u003cp\u003eMarital status\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e \u003cp\u003eSingle\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e12 (11.9%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e \u003cp\u003eMarried\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e57 (56.4%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e \u003cp\u003eWidowed\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e15 (14.9%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e \u003cp\u003eDivorced\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e11 (10.9%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e \u003cp\u003eCohabiting (civil partnership)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e6 (5.9%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"5\" rowspan=\"6\"\u003e \u003cp\u003eEducational level\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e \u003cp\u003eIlliterate\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e1 (1.0%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e \u003cp\u003ePrimary education\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e38 (37.6%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e \u003cp\u003eSecond level of primary education\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e19 (18.8%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e \u003cp\u003eThird level of primary education\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e12 (11.9%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e \u003cp\u003eSecondary education\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e19 (18.8%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e \u003cp\u003eHigher education\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e12 (11.9%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"2\" rowspan=\"3\"\u003e \u003cp\u003eIndependence for ADL\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e \u003cp\u003eIndependent\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e53 (52.5%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e \u003cp\u003eModerately dependent\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e11 (10.9%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e \u003cp\u003eHighly dependent\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e37 (36.6%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"4\"\u003e\u003cb\u003eNote.\u003c/b\u003e Percentages are based on valid responses.\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec14\" class=\"Section3\"\u003e \u003ch2\u003e4.3.2. Reliability\u003c/h2\u003e \u003cp\u003eWe assessed the internal consistency of the OSAS-Pt using Cronbach\u0026rsquo;s α and McDonald\u0026rsquo;s ω coefficient, of the 20 items (prevalence and frequency); of the 15 and 14 items identified in the original factor structure (prevalence and frequency); and of the 17 items that comprise the 3-factor model.\u003c/p\u003e \u003cp\u003eFor the results based on the prevalence of 20 items, Cronbach\u0026rsquo;s α\u0026thinsp;=\u0026thinsp;0.901 and McDonald\u0026rsquo;s ω\u0026thinsp;=\u0026thinsp;0.901. Based on the frequency of 20 items, Cronbach\u0026rsquo;s α\u0026thinsp;=\u0026thinsp;0.908 and McDonald\u0026rsquo;s ω\u0026thinsp;=\u0026thinsp;0.912. Both Cronbach\u0026rsquo;s α values are indicative of excellent internal consistency [\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e, \u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e]. Both McDonald\u0026rsquo;s ω are indicative of an excellent internal consistency [\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e, \u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eFor the results based on the prevalence of the 14 items of the original factor structure, Cronbach\u0026rsquo;s α\u0026thinsp;=\u0026thinsp;0.878 and McDonald\u0026rsquo;s ω\u0026thinsp;=\u0026thinsp;0.880. For the results based on the frequency of the 14 items of the original factor structure, Cronbach\u0026rsquo;s α\u0026thinsp;=\u0026thinsp;0.882 and McDonald\u0026rsquo;s ω\u0026thinsp;=\u0026thinsp;0.887. Both Cronbach\u0026rsquo;s α values are indicative of good internal consistency [\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e, \u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e]. Both McDonald\u0026rsquo;s ω are indicative of good internal consistency [\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e, \u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eFor the results based on the prevalence of the 17 items of the three-factor structure, Cronbach\u0026rsquo;s α\u0026thinsp;=\u0026thinsp;0.896 and McDonald\u0026rsquo;s ω\u0026thinsp;=\u0026thinsp;0.897. For the results based on the frequency of the 17 items of the three-factor structure, Cronbach\u0026rsquo;s α\u0026thinsp;=\u0026thinsp;0.905 and McDonald\u0026rsquo;s ω\u0026thinsp;=\u0026thinsp;0.907. Both Cronbach\u0026rsquo;s α values are indicative of good internal consistency [\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e, \u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e]. Both McDonald\u0026rsquo;s ω are indicative of good internal consistency [\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e, \u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e].\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec15\" class=\"Section3\"\u003e \u003ch2\u003e4.3.3. Construct validity - Confirmatory factor analysis\u003c/h2\u003e \u003cp\u003eWe conducted a CFA to test the prevalence based five-factor structure identified in the original EFA (Additional file 2), which included five latent factors and 14 items that assessed the symptoms prevalence: Factor 1 (Coating of tongue, dirty mouth, taste disturbance, bad breath); Factor 2 (Lip discomfort, Difficulty speaking, Difficulty chewing, Difficulty swallowing); Factor 3 (Mouth discomfort, Ulcers in mouth); Factor 4 (jagged teeth, sensivity of teeth); Factor 5 (cracking of lips, cracking of corners of mouth). Overall model fit results indicate a very good fit (scaled CFI\u0026thinsp;=\u0026thinsp;0.985; SRMR\u0026thinsp;=\u0026thinsp;0.085; RMSEA\u0026thinsp;=\u0026thinsp;0.045 95% CI [0.000, 0.077]). The observed Parsimony Normed Fit Index (PNFI) was 0.697. A very high loading for item15_freq of 1.288, as well as a negative variance for that item (\u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\:\\beta\\:=\\:-0.659\\)\u003c/span\u003e\u003c/span\u003e). Negative variances are indicative of improper solutions and local model misspecification. A model with inadmissible parameter estimates cannot be considered psychometrical sound, regardless of global fit statistics [\u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e]. Therefore, this model was not retained.\u003c/p\u003e \u003cp\u003eWe conducted another CFA to test the original frequency-based five-factor structure identified in the original EFA (Additional file 3). This model included five latent factors and 14 items that assessed the symptoms frequency: Factor 1 (Items 7; 8; 9), Factor 2 (items 6; 10; 11; 12), Factor 3 (items 2; 20), Factor 4 (items 3; 4; 5) and Factor 5 (items 14; 15). The scaled results indicate a good model fit with SRMR\u0026thinsp;=\u0026thinsp;0.058, RMSEA\u0026thinsp;=\u0026thinsp;0.065 (95% CI [0.030, 0.093] \u003cem\u003ep\u003c/em\u003e=.209). The observed PNFI was 0.688. A very high loading for item15_freq exceeding 1.90, as well as a negative variance for that item (\u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\:\\beta\\:=\\:-0.279\\)\u003c/span\u003e\u003c/span\u003e). Negative variances and improper solutions indicate local model misspecification. We also observed some very high latent factor correlations (approaching 0.90). These results are suggestive of overlapping latent variables. A model with inadmissible parameter estimates cannot be considered psychometrical sound, regardless of global fit statistics [\u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e]. Therefore, this model was not retained.\u003c/p\u003e \u003cp\u003eConsidering the instability of the five factor models, a theoretically informed three-factor model was tested (Additional file 4). This model comprised 17 items distributed across three correlated latent variables. The three-factor model demonstrated good overall fit (scaled CFI\u0026thinsp;=\u0026thinsp;0.979; SRMR\u0026thinsp;=\u0026thinsp;0.67; RMSEA\u0026thinsp;=\u0026thinsp;0.60, CI 95% [0.033, 0.082]). The observed PNFI was 0.790. No inadmissible parameter estimates were identified. All factor loadings were statistically significant and within acceptable ranges (from 0.57 to 0.98). No negative residual variances or loadings greater than 1.00 were observed. The latent covariance matrix was positive definite, and the inter-factor correlations did not exceed 0.90. Reliability estimates were acceptable to good. Cronbach\u0026rsquo;s α ranged from 0.738 (Factor 3) to 0.896 (Factor 2). Ordinal α ranged from 0.850 (Factor 1) to 0.936 (Factor2). Composite reliability indices ω₁, ω₂, ω₃, ranged from 0.786 to 0.936. AVE for Factor1 was 0.612; for Factor 2 was 0.622; for Factor3 was 0.741, all values indicative of adequate convergent validity. Thus, the three-factor model was retained.\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e"},{"header":"5. DISCUSSION","content":"\u003cp\u003e This study presents, to our knowledge, the first multi-symptom oral assessment instrument validated for Portuguese patients with advanced cancer. The use of inappropriate tools to assess oral symptoms hinders the evaluation of oral symptom management strategies [\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e]; therefore, validated instruments for assessing oral symptoms are essential to examine the effectiveness of interventions to manage oral symptoms in both research and clinical practice [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e, \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eSome participants stated that some items may not apply to all patients (e.g., denture-fitting problems). Excessively long instruments may hinder clinical feasibility for both professionals and patients [\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e] and fatigue is known to have a detrimental effect on quality of life of patients with advanced cancer [\u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e]. Although the CFA did not reveal issues with the item \u0026ldquo;Coating of tongue\u0026rdquo;, some participants found it difficult to understand. User feedback is essential in instrument development [\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e]; therefore, future studies could develop a shorter version to minimize patient burden, modelled after the MSAS short form [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e, \u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e35\u003c/span\u003e], as proposed by the original authors [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]; adopt less clinical terms to enhance comprehensibility [\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e]; and clarify that certain items may be non-applicable.\u003c/p\u003e \u003cp\u003eAn EFA cannot assess factor stability or detect inadmissible solutions [\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e], such as Heywood cases [\u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e36\u003c/span\u003e], which are only identified with a CFA [\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e, \u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e36\u003c/span\u003e]. Heywood cases, as those identified in the five-factors models, are often the result of a structure misspecification [\u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e37\u003c/span\u003e]. Both five-factors models had acceptable global fit indices [\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e]. However, they presented inadmissible solutions and structural instability, such as Heywood cases [\u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e36\u003c/span\u003e, \u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e38\u003c/span\u003e] and high inter-factor correlations that compromised construct distinction [\u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e]. Construct validation requires testing alternative models informed by theory and empirical evidence [\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e, \u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e]. Guided by the Symptom Management Theory, empirical evidence, and the data derived from the five-factor structure models, we tested a three-factor model, which demonstrated good fit, statistical stability, and greater parsimony with a higher PNFI [\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eThe three-factor model comprises 17 items, that assess symptom frequency loaded into three factors: Factor 1 \u0026ndash; \u0026ldquo;\u003cb\u003eChanges in oral functions\u0026rdquo;\u003c/b\u003e (items: Taste disturbance; Difficulty chewing; Difficulty swallowing; Difficulty speaking \u0026ndash; items 6\u0026ndash;9, respectively). Factor 2 \u0026ndash; \u003cb\u003e\u0026ldquo;Changes in oral mucosa\u0026rdquo;\u003c/b\u003e, (items: Dry mouth; Mouth discomfort/pain; Lip discomfort; Cracking of lips; Cracking of corners of mouth; \u0026ldquo;Dirty\u0026rdquo; mouth; Coating of tongue; Bad breath; Burning sensation in mouth; Altered sensation in mouth \u0026ndash; items 1\u0026ndash;5; 10\u0026ndash;12; 18, 19 respectively). Factor 3 \u0026ndash; \u0026ldquo;\u003cb\u003eDental changes\u0026rdquo;\u003c/b\u003e (items \u0026ndash; Toothache/pain in teeth; Sensitivity of teeth; Jagged teeth \u0026ndash; items 13\u0026ndash;15, respectively). Two items did not fit the factor structure as they can be considered signs: Bleeding from the mouth and Ulcers in mouth (items 17 and 20, respectively). The item Denture fitting problems (item 16) also did not fit the model structure, as it is not applicable to all the possible patients that the instrument was developed for. Although these items do not load into any of the identified factors, they remain clinically relevant to assess oral problems in patients with advanced cancer [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e, \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e], therefore we decided to maintain these items in the OSAS-Pt.\u003c/p\u003e \u003cdiv id=\"Sec17\" class=\"Section2\"\u003e \u003ch2\u003e5.1. Limitations\u003c/h2\u003e \u003cp\u003eThe absence of data from the original OSAS population did not allow for cross-cultural validation, restricting the study to construct validation. Responsiveness [\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e] was not assessed, as this would require a longitudinal study and repeated patient participation, which was considered ethically inappropriate given the expected population\u0026rsquo;s frailty and uncertainty regarding the validation of the translated version. As instrument development is iterative [\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e], future studies should examine responsiveness of the OSAS-Pt. Although item 6 (Coating of tongue) was statistically adequate, reported comprehension difficulties warrant reconsideration of its translation in future research.\u003c/p\u003e \u003c/div\u003e"},{"header":"6. CONCLUSIONS","content":"\u003cp\u003eThe OSAS-Pt was well understood, accepted, considered relevant and feasible by the participants of this study. The five-factor structures were not psychometrically supported due to inadmissible parameter estimates and structural instability. The three-factor model demonstrated satisfactory model fit, stable parameter estimates, adequate reliability, and acceptable construct validity. Accordingly, we retained the three-factor model as the most appropriate representation of the instrument\u0026rsquo;s latent structure in this population. The OSAS-Pt is a psychometrically robust and culturally appropriate instrument to assess oral symptoms in Portuguese patients with advanced cancer.\u003c/p\u003e \u003cp\u003eFuture studies can further confirm the identified factor-structure in other populations, revise the items that are less comprehensible, investigate the OSAS-Pt responsiveness, and develop a short-form OSAS-Pt more adequate to clinical practice.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e \u003ch2\u003eEthics approval\u003c/h2\u003e \u003cp\u003e This study was performed in line with the principles of the Declaration of Helsinki. Ethical approval was obtained from the Ethics Committee of all involved institutions: Administra\u0026ccedil;\u0026atilde;o Regional de Sa\u0026uacute;de do Alentejo (15/CE/2023); Instituto S\u0026atilde;o Jo\u0026atilde;o de Deus (Ethics Committee approval on the 31st of March 2023); Unidade Local de Sa\u0026uacute;de do Litoral Alentejano (E/5635/23/CA); Unidade Local de Sa\u0026uacute;de do Norte Alentejano (13/2023); Unidade Local de Sa\u0026uacute;de do Algarve (on the 4th of March 2024).\u003c/p\u003e \u003c/p\u003e\u003ch2\u003eFunding\u003c/h2\u003e \u003cp\u003eThe authors declare that no funds, grants, or other support were received during the preparation of this manuscript.\u003c/p\u003e\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003eRicardo Serra and Helena Arco contributed to the study conception and design. Data collection was performed by Alexandra Barreiros, Ana Mour\u0026atilde;o, Ana Serra, Gabriela Serra, Rita Louren\u0026ccedil;o, Ros\u0026aacute;rio Neto, Sofia Coito, and V\u0026acirc;nia Cunha. Material preparation and analysis were performed by Ricardo Serra, Adelaide Proen\u0026ccedil;a, Andreia Costa and Helena Arco. The first draft of the manuscript was written by Ricardo Serra and all authors commented on previous versions of the manuscript. All authors read and approved the final manuscript.\u003c/p\u003e\u003ch2\u003eAcknowledgement\u003c/h2\u003e\u003cp\u003eWe would like to thank Dr. Andrew Davies and colleagues, for developing the OSAS and granting authorization to translate and validate it in the Portuguese population, as well as all the staff that cooperated at the study sites: Unidade Local de Sa\u0026uacute;de do Alto Alentejo (Oncology Service and Palliative care Unit); Unidade Local de Sa\u0026uacute;de do Litoral Alentejano (Palliative Care Unit); Unidade Local de Sa\u0026uacute;de do Alentejo Central (Intra-Hospital Palliative Care Support Team); Unidade Local de Sa\u0026uacute;de do Algarve (Palliative Care Unit); Instituto S\u0026atilde;o Jo\u0026atilde;o de Deus, Hospital de Montemor (Palliative Care Unit). RS is a nursing PhD student at Lisbon Nursing School of the University of Lisbon; this study forms part of his doctoral thesis.\u003c/p\u003e\u003ch2\u003eData Availability\u003c/h2\u003e\u003cp\u003eThe datasets supporting the conclusions of this article are included within the article (and its additional files).\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eDodd M, Janson S, Facione N, Faucett J, Froelicher E, Humphreys J et al (2001) Advancing the science of symptom management. J Adv Nurs 33:668\u0026ndash;676\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eDavies A, Buchanan A, Todd J, Gregory A, Batsari KM (2021) Oral symptoms in patients with advanced cancer: an observational study using a novel oral symptom assessment scale. 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Eur J Psychotraumatol Taylor Francis Ltd 16. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1080/20008066.2024.2444745\u003c/span\u003e\u003cspan address=\"10.1080/20008066.2024.2444745\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"Palliative Care, Signs and Symptoms, Patient Reported Outcome Measures, Oral Health, Neoplasms","lastPublishedDoi":"10.21203/rs.3.rs-9393168/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-9393168/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003ePurpose\u003c/h2\u003e \u003cp\u003e This study aimed to Translate the Oral Symptom Assessment Scale into Portuguese; and evaluate the construct validity of the Portuguese version of the Oral Symptom Assessment Scale.\u003c/p\u003e\u003ch2\u003eMethods\u003c/h2\u003e \u003cp\u003eA methodological, quantitative descriptive, multicentred, cross-sectional study was conducted. The translation, cross-cultural adaptation and construct validity followed COSMIN guidelines. The original instrument was translated to Portuguese, the final translated version was pre-tested in a sample of 30 patients with advanced cancer, locally or metastatically. The final translated version was applied to a sample of 101 patients with advanced cancer, locally or metastatically in an oncology outpatient consultation or receiving hospital palliative care. Three hypothesised structures were analysed with confirmatory factor analysis, following COSMIN guidelines.\u003c/p\u003e\u003ch2\u003eResults\u003c/h2\u003e \u003cp\u003eThe Portuguese version of the OSAS was well understood, accepted, considered relevant and feasible by the participants. A three-factor model with 17 items was retained with a good overall fit (scaled CFI\u0026thinsp;=\u0026thinsp;0.979; SRMR\u0026thinsp;=\u0026thinsp;0.67; RMSEA\u0026thinsp;=\u0026thinsp;0.60, CI 95% [0.033, 0.082]). No inadmissible parameter estimates were identified in the three factor-model. All factor loadings were statistically significant and within acceptable ranges (from 0.57 to 0.98).\u003c/p\u003e\u003ch2\u003eConclusions\u003c/h2\u003e \u003cp\u003eThe three-factor model demonstrated satisfactory model fit, stable parameter estimates, adequate reliability, and acceptable construct validity. Accordingly, we retained the three-factor model as the most appropriate representation of the instrument\u0026rsquo;s latent structure in this population. The Portuguese version of the OSAS is adequate for research and clinical purposes in Portuguese patients with advanced cancer.\u003c/p\u003e\u003ch2\u003eClinical Trial number:\u003c/h2\u003e \u003cp\u003eNot applicable.\u003c/p\u003e","manuscriptTitle":"Field Testing of the Psychometric Properties of the Oral Symptom Assessment Scale – Portuguese Version: A Methodological Study","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-04-23 12:34:52","doi":"10.21203/rs.3.rs-9393168/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"69aea53c-0132-4b6f-8dd9-8b3173335040","owner":[],"postedDate":"April 23rd, 2026","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2026-04-23T12:34:53+00:00","versionOfRecord":[],"versionCreatedAt":"2026-04-23 12:34:52","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-9393168","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-9393168","identity":"rs-9393168","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}