Validity and reliability testing of the Pelvic Pain Impact Questionnaire

Initially, 269 participants were recruited from endometriosis-related social media groups and 29 were excluded; therefore, 240 adult women suffering from chronic pelvic pain and endometriosis (mean age 34.18 ± 6.7) participated in the study (Fig.  2 ). Fig. 2 Flow chart of the sampling process. Flow chart of the sampling process. The sample’s profile and sociodemographic characteristics are shown in Table  1 . Table 1 Sociodemographic characteristics of the sample. Variable Final sample n  = 240 n (%) 1. Marital status  Living alone 29 (12.1%)  Living with partner 89 (37.1%)  Married 117 (49.0%)  Divorced 4 (1.7%) 2. Educational level  Elementary school 4 (1.7%)  Secondary school 99 (41.3%)  Higher education 137 (57.1%) 3. Work category  Sedentary 139 (58.4%)  Light physical 52 (21.8%)  Heavy physical 7 (2.9%)  Standing 27 (11.3%)  Unemployed 13 (5.5%) 4. Residence  City 105 (43.8%)  Village 39 (16.3%)  Administrational center 37 (15.4%)  Capital 59 (24.6%) 5. Pelvic pain duration (years) 9.23 ± 7.7 6. Gynaecology surgery 184 (76.6%) 7. Number of children  0 126 (62.7%)  1 47 (11.9%)  2 24 (11.9%)  3 4 (2.0%) Sociodemographic characteristics of the sample. Floor and ceiling effects were insignificant, 0.7% and 8.9% of the participants scored the lowest and highest possible scores, respectively. Table  2 shows the descriptive results of the measurement instruments. Table 2 Average scores of the applied measurement tools. Outcome measurements Mean Pelvic Pain Impact Questionnaire PPIQ-HU 8 17.40 ± 8.075 Pelvic Pain Impact Questionnaire PPIQ-HU 10 22.01 ± 10.50 Average pain intensity – (NRS) 5.52 ± 2.22 Strongest pain intensity in the last month - NRS 7.29 ± 2.30 Current pain intensity, NRS 4.45 ± 2.89 Perceived stress level - PSS 31.52 ± 8.48 Pain catastrophizing - PCS 28.49 ± 13.86 Health-related quality of life - SF-36 Physical functioning (PF) 71.60 ± 23.51 Role limitations due to physical health 39.43 ± 40.09 Role limitations due to emotional problems 46.86 ± 44.05 Energy/fatigue 43.85 ± 13.41 Emotional wellbeing 46.18 ± 14.20 Social functioning 59.52 ± 32.09 Pain 42.63 ± 25.66 General health 43.33 ± 22.83 Average scores of the applied measurement tools. The internal consistency of the PPIQ–HU 8 was excellent with Cronbach’s α = 0.881 (Table  3 ), and Ω = 0.885. According to a recently published simulation model, Cronbach’s α indicator cutoff point for 8-item questionnaires of 0.784 was defined based on a minimum inter-item correlation of 0.4. Test-retest reliability of the PPIQ-HU in a sample of 40 women yielded excellent results (ICC = 0.977, 95% CI 0.955–0.988). The item-total correlation coefficients in our study ranged from 0.498 (item number 8) to 0.790 (item number 6), as presented in Table  3 . All item-total correlation coefficients were statistically significant, indicating that the direction of the scoring between each item and the total score was consistently positive. Table 3 Item-total statistics. Scale Mean if Item deleted Scale Variance if Item Deleted Corrected Item-Total correlation Cronbach’s α if Item deleted Item-total statistics  PPIQ1 14.83 51.205 0.698 0.862  PPIQ2 14.71 50.743 0.736 0.859  PPIQ3 15.29 50.061 0.641 0.867  PPIQ4 15.11 51.889 0.592 0.872  PPIQ5 15.92 52.072 0.536 0.878  PPIQ6 15.45 48.872 0.790 0.852  PPIQ7 15.16 49.298 0.733 0.858  PPIQ8 15.32 52.047 0.498 0.883 Item-total statistics. The Confirmatory Factor Analysis (CFA) confirmed the one-factor structure of the PPIQ-HU questionnaire in our sample, with the following results: RMSEA = 0.052, TLI (Tucker-Lewis Index) = 0.981, CFI = 0.989, χ 2 = 27.882, degrees of freedom (df) = 17, p  < 0.001, and χ 2 /df = 1.640. All items loaded significantly onto the scale, with standardized factor loadings ranging from 0.54 to 0.84, and all p-values being less than 0.01. Modification indices showed a connection between different items presented on Fig.  3 . Fig. 3 Confirmatory factor analysis: initial model. Confirmatory factor analysis: initial model. Table  4 presents the correlations between PPIQ–HU and other measurement tools. Significant weak to moderate negative correlations were found between SF-36 subscales and the PPIQ-HU total scores, and significant moderate positive correlations between PCS, PSS, and NRS and the PPIQ-HU total scores. The results of the Bayesian correlation analysis are also presented in Table  4 . Table 4 Convergent validity of the PPIQ-HU8 and the other measurement tools ( n  = 240). Questionnaire Correlation with total score of PPIQ HU (r) ( n  = 240) Bayesian correlation analysis of PPIQ HU (τb, BF 10 ) ( n  = 240) SF-36  Physical functioning − 0.576** − 0.452 7.504 × 10 + 22  Role functioning physical − 0.577** − 0.504 1.726 × 10 + 31  Social functioning − 0.574** − 0.477 7.616 × 10 + 27  Bodily pain − 0.706** − 0.588 7.547 × 10 + 42  Role functioning emotional − 0.385** − 0.346 1.483 × 10 + 14  Emotional well-being − 0.243** − 0.138 20.506  Energy/vitality − 0.447** − 0.345 1.193 × 10 + 14  General health perception − 0.390** − 0.295 8.894 × 10 + 9  PSS 0.370** 0.271 1.733 × 10 + 9  PCS 0.547** 0.428 1.537 × 10 + 22  NRS current 0.526** 0.460 6.908 × 10 + 25  NRS average in last month 0.595** 0.518 1.157 × 10 + 33  NRS strongest in last month 0.535** 0.487 1.024 × 10 + 25 (level of significance ** p  < 0.001) Convergent validity of the PPIQ-HU8 and the other measurement tools ( n  = 240). (level of significance ** p  < 0.001) During the examination of discriminant validity, the Mann-Whitney U test and the Bayesian Mann-Whitney U test were conducted, and the test results indicated a significant difference in the mean scores of the PPIQ-HU between the two groups formed based on the average NRS in the previous month ( p  < 0.001). The “mild pain” group (10.98 ± 6.53, n  = 81) and the “moderate or severe pain” group (20.31 ± 7.083, n  = 159) showed significant ( p  < 0.001) differences regarding the PPIQ-HU mean value scores (Table  5 ). Cohen’s d effect size was calculated ( r  = 0.54). Table 5 Known-groups validity of the sample. Mild pain ( n  = 81) Moderate or severe pain ( n  = 159) p -value Cohen’s d effect size BF 10 PPIQ-HU mean value and standard deviation (points) 10.98 ± 6.531 20.31 ± 7.083 p  < 0.001 r  = 0.54 1.903 × 10 + 6 Known-groups validity of the sample.

The present study is a cross-sectional online survey distributed via social media support groups in Hungary from January 2023 to May 2023. Females with endometriosis-related chronic pelvic pain, aged between 18 and 50, and living in Hungary, were eligible to participate voluntarily in our study. The sampling method was convenient. The exclusion criteria included individuals not diagnosed with endometriosis, or not suffering from chronic pelvic pain, having severe conditions (such as malignant tumors, not treated psychiatric disease, not cooperative, illiterate), pregnant women, or women under 18 and above 50 years of age. We used the validated Hungarian versions of the following questionnaires at both evaluations: Perceived Stress Scale (PSS14), Pain Catastrophizing Scale (PCS), 36-item Short Form Health Survey (SF-36), and Numeric Rating Scale (NRS). The self-administered PPIQ 17 is a simple questionnaire that aims to assess how pelvic pain affects daily life. The questionnaire consists of 8 mandatory and two optional questions, each rated on a 5-point Likert scale. The total score ranges from 0 to 32, with higher scores indicating a more significant impact of pelvic pain on the individual’s daily activities. The original English version of the questionnaire showed excellent internal consistency (Cronbach’s α = 0.92) and test-retest reliability. The PCS 18 is a self-administered measurement instrument consisting of 13 statements reflecting pain-related thoughts and feelings. The questionnaire can be divided into three categories: rumination (items 8–11), magnification (items 6, 7, and 13), and helplessness (items 1–5 and 12). Each item is scored on a 5-point scale, with total scores ranging from 0 to 52; higher scores indicate greater pain catastrophizing. The Hungarian version of the Pain Catastrophizing Scale (PCS- 19 has good internal consistency, with Cronbach’s alpha values of 0.74 to 0.93 across the subscales 19 . The 36 Item Short-Form Health Survey 20 is designed to assess the participants’ health-related quality of life by eight health concepts, and its scoring process consists of two steps. First, scores are summed for each domain, resulting in scores that range from 0 to 100, where 0 indicates the lowest health-related quality of life and 100 represents the highest. Then, the items within each scale are averaged to create eight domains: Physical functioning (10 items), Bodily pain (2 items), Role limitations due to physical health problems (4 items), Role limitations due to emotional problems (3 items), Emotional well-being (5 items), Social functioning (2 items), Energy/fatigue (4 items), General health perceptions (6 items). During the cross-cultural adaptation of the SF-36 the Hungarian version of the 36 Item Short-Form Health Survey 21 showed excellent internal consistency: Cronbach’s α = 0.93. PSS-10 22 is a self-administered measurement tool designed to assess stress levels and “the degree to which individuals appraise situations in their lives as stressful”. The scale consists of 10 questions, each question with 5 answer options related to frequency, varying from 0 to 4. A higher score means higher stress levels, 40 is the highest possible score. The Hungarian version of PSS-10 23 has demonstrated good internal consistency (Cronbach α = 0.85). The scale 24 utilized in this study is a well-recognized and validated instrument in the literature, specifically designed to assess subjective pain levels on a scale from 0 to 10. On this scale, 0 indicates no pain, while 10 signifies the most severe pain imaginable. Participants were asked to rate their average and maximum pain levels over the past four weeks, as well as their current pain intensity. The study was conducted anonymously, with all participants required to give informed consent after receiving detailed information about the research. They could only proceed with the questionnaire after providing their consent. Participation remained anonymous, as the study was conducted through an online questionnaire that did not require any registration or identification. Data was collected using a research ID to ensure participant privacy. Ethical approval for the study was obtained from the Institutional Review Board of the Faculty of Medicine, University of Pécs, in 2023 (no.: 9534-PTE 2023;), and all methods used in this study were performed in accordance with the relevant guidelines and regulations. After obtaining consent from the original investigator of the PPIQ for its translation, cross-cultural adaptation, and validation into Hungarian, the linguistic validation was completed according to the relevant guidelines 25 . The process is presented on Fig.  1 . Fig. 1 Linguistic validation of the PPIQ. Linguistic validation of the PPIQ. During the validation process, the PPIQ was translated from English to Hungarian by two independent translators. The first translator, a physiotherapist with a clinical background, possessed familiarity with the concepts underlying the questionnaire, while the second translator, an English teacher, had no prior knowledge of the questionnaire and lacked a clinical perspective. Following the completion of the translations, a synthesis was undertaken to ensure equivalence with the original version. Subsequently, an independent physiotherapist with advanced English proficiency performed a back-translation of the PPIQ into English. A committee, comprising a medical doctor, an English teacher, a physiotherapist, and a university lecturer, developed the pre-final version of the questionnaire. This pre-final version was later piloted with a sample of 15 Hungarian women with various backgrounds, experiencing endometriosis and chronic pelvic pain (CPP). These participants were invited to provide feedback through telephone interviews regarding the readability, cultural relevance, and comprehensiveness of the translated version. Feedback resulted in only minor revisions; for instance, the term 'energiáját' was substituted with 'energiaszintjét' for better understanding.” Additionally, five participants noted that certain sentences could benefit from improvement and clarification, indicating that the introductory sentences were overly lengthy. The initial calculation of the Readability Index for the questionnaire indicated a level of difficulty that was suitable only for educated adults. Following a process of further simplification, the PPIQ-HU showed a Flesch-Kincaid Grade Level of 5.8, Ease Score: 81.1 and Reading level: 6th Grade. This revised score reflects a more suitable difficulty level for adult respondents with different educational backgrounds. Consequently, the final Hungarian version of the self-administered PPIQ-HU was approved. Following the creation of the final version of the questionnaire, we evaluated the following psychometric properties of the PPIQ-HU: internal consistency, test-retest reliability, structural validity, convergent validity, and discriminative validity. Internal consistency examines the degree to which items within an instrument are interconnected, indicating their strength of homogeneity. Cronbach’s α was used to verify internal consistency; values between 0.70 and 0.95 were considered adequate 26 . For further clarification, based on a 2022 study 27 the cutoff points for Cronbach’s α for 8-item questionnaires were also used to determine the reliability of the PPIQ-HU. The minimum acceptable interitem correlation of 0.4 was applied. Based on this criterion, the corresponding threshold for Cronbach’s α was set at 0.784. Values equal to or exceeding this level were considered indicative of acceptable reliability. McDonald’s Ω was also calculated to provide a complementary estimate of internal consistency, particularly useful in the context of multidimensional constructs. Test-retest reliability was assessed with an intraclass correlation coefficient (ICC). ICC values of 0.75–1.00 were interpreted as excellent 28 . We asked 40 participants to fill in the questionnaire 2 weeks after the initial testing according to the COSMIN guideline and other relevant studies 25 , 29 , 30 . Descriptive statistics were used to determine the characteristics of the sample, estimate central tendency, and assess the variability of the data set. The results were presented as means, standard deviations (SD), or percentages (%). Content validity was evaluated by examining score distributions and checking for floor and ceiling effects. These effects are considered to be present if more than 15% of the sample achieves the minimum (floor) or maximum (ceiling) possible score. We determined the sample size to assess internal consistency and construct validity according to the COSMIN guideline 25 . Our study confirmed the structural validity of the instrument using confirmatory factor analysis (CFA) and reliability statistics such as comparative fit index (CFI), Tucker-Lewis index (TLI), root-mean-square error approximation (RMSEA), and 90% confidence interval (CI). A ratio of < 3 between the chi-square test and degrees of freedom, CFI and TLI of 0.90 or more, and RMSEA values of 0.08 or less indicated a good model fit. We calculated factor loadings for each item and identified loadings below 0.5 for potential item reduction 31 . Convergent validity of the PPIQ was examined using Spearman’s rank correlation analysis to assess the relationship between the total score of the PPIQ and the NRS and SF-36, PCS and PSS scores. The correlation was classified as moderate (0.3  0.69) or strong ( r  > 0.7) 32 . Bayesian correlation analysis was performed to enhance the results of the convergent validity analysis. For the examination of known-group validity, based on the average scores of NRS over the past 4 weeks, 2 groups were created (0–4, mild pain 5–10, moderate and severe). Mann-Whitney U-test was used to establish discriminative validity to examine the differences in PPIQ scores between patients having mild or moderate/severe pain 33 . Cohen’s d effect size was calculated for known-group validity analysis, setting the threshold by 0.1 for minimum, 0.3 for medium and 0.5 for large effect size 34 . Data analysis was carried out using IBM SPSS 28.0 software and IBM SPSS AMOS 29.0 (SPSS Inc., Chicago, IL) version. The level of significance was set at p  < 0.05.

The current study indicates that the PPIQ-HU is a valid and reliable instrument for evaluating the effect of chronic pelvic pain on individuals with chronic pelvic pain and endometriosis. The translation and cultural adaptation of the PPIQ-HU could contribute to further studies, therapeutic and educational programs 37 with monitoring therapeutic effect and the factors influencing the impact of chronic pelvic pain on women’s everyday lives. The translation and cultural adaptation of the PPIQ-HU may facilitate further interventional studies and educational programs on chronic pelvic pain and could lead to further understanding of the factors influencing its impact on women’s daily lives in Hungary.

Our study aimed to translate and cross-culturally adapt the PPIQ into the Hungarian language and examine its reliability and validity on a sample of women suffering from endometriosis-related chronic pelvic pain. PPIQ itself was used in other studies examining the impact of chronic pelvic pain. We examined the psychometric properties of the Hungarian version of PPIQ-HU. Our sample consisted of patients suffering from endometriosis and chronic pelvic pain, similar to the original development and validation study of Jane Chalmers 17 where the authors examined a sample consisting of women suffering from chronic pelvic pain due to endometriosis, adenomyosis, tight pelvic floor, pudendal neuralgia, pelvic congestion syndrome etc. According to the original development study the PPIQ is suitable for use across varying types of pelvic pain, including endometriosis-related pelvic pain. The psychometric analysis and validation process was conducted for the 8-item version of the questionnaire, as according to Jane Chalmers’ original study, the last two questions were included only as supplementary and did not contribute to the overall PPIQ score. The mean score of the PPIQ-HU in our study was 17.04 ± 8.07, while the mean score of the Turkish validation was 14.76 ± 7.99 points in a sample of patients with chronic pelvic pain. Similar to the Turkish validation study 16 in the current study CFA supported the one-factor structure of the PPIQ. With each item deleted, Cronbach’s α remained stable. No significant ceiling and floor effects were found. The PPIQ-HU showed good psychometric properties with good indications of reliability and validity. The PPIQ-HU showed excellent internal consistency (Cronbach’s α = 0.881, McDonald’s Ω = 0.885), in congruence with the Turkish validation (Cronbach’s α = 0.920). Both reliability coefficients exceeded the established threshold, indicating adequate internal consistency. The PPIQ-HU demonstrated high test-retest reliability (ICC = 0.977 95% CI 0.955–0.988) congruent with the Turkish validation study of the PPIQ, as ICC for test-retest reliability was 0.95 (95% confidence interval: 0.93–0.97). In the original validation study test-retest reliability was good (ICC 0.87–0.94), and the overall test-retest reliability was also good (intraclass correlation coefficient 0.91; confidence interval: 0.83–0.96; p  < 0.001). We used 2 weeks between initial test and retest suggested by the relevant literature 25 , 29 . Since pelvic pain significantly affects people’s daily lives, we examined the correlations between chronic pelvic pain and questionnaires identifying pain catastrophizing and health-related quality of life. Convergent validity was confirmed in our study, as the results indicated that the PPIQ-HU was significantly and positively associated with measures of pain catastrophizing, perceived stress, and pain levels 35 . The correlation between the PPIQ-HU and the SF36 domains was moderate ( r =− 0.243 to 0.577). The findings were validated through a supplementary Bayesian correlation analysis. A post hoc analysis using GPower software 36 was conducted to examine the power analysis for convergent validity testing (correlation analysis), resulting in adequate values (Power (1-ß err prob): 0.968–1.000. The results of the current study indicated a significant difference in the mean scores of the PPIQ-HU between the two groups 33 formed based on the NRS values of the participants ( p  < 0.001). An additional Bayesian Mann-Whitney U test was performed to increase the reliability of the known-group validity testing. A post hoc analysis was conducted to assess the power analysis for discriminant validity (Mann-Whitney U test), showing adequate values (Power (1-ß err prob): 0.968–1.000. The effect size of the known-group validity analysis was calculated, showing a large effect size ( r  = 0.54) 34 . Our study fills a gap as the PPIQ-HU is an ideal tool for rapid, quality-of-life-focused evaluation during clinical visits. Based on the psychometric indicators of the PPIQ-HU, it shows excellent internal consistency, stable test-retest reliability, good content and structural validity, generally acceptable convergent validity, and the effect size for discriminative validity is large. Despite the strengths of the study, the following limitations need to be considered. First, all patients were recruited from thematic social media groups, which may limit the representativeness of the sample. Additionally, the diagnosis of chronic pelvic pain and endometriosis was self-reported, rather than clinically verified. The number of participants was 240, which is an average number. The test-retest reliability analysis has a limited but mathematically adequate sample size of 40. The PPIQ-HU is not yet included in clinical practice and in the current clinical guidelines (urological, gynaecological, family medicine, etc.). Currently, it is mainly used for research purposes. This fact is unfortunate because it measures precisely the dimensions that are important to women (energy, work, sleep, intimacy, etc.). Further reliability testing on a larger sample and recruiting a more representative sample would be advisable. As the PPIQ has only been used for research purposes, future studies could be performed to prove its clinical usability, including high-quality randomized controlled trials. To ensure more focused patient-centered care, an examination of the individual sub-questions could be considered. Testing the psychometric properties of the questionnaire for other pathologies related to chronic pelvic pain, like IBS, PCOS, would also be advisable. The Hungarian adaptation and validation of the PPIQ-HU could contribute to developing patient-centered care in the Hungarian population with pelvic pain and endometriosis, by measuring the effect of interventions designed to alleviate chronic pelvic pain. This tool could lead to a better understanding of the impact of pelvic pain on everyday life. This questionnaire could also be used for validated baseline and follow-up measurements when examining the effectiveness of therapeutic interventions (e.g., CBT, physiotherapy, acupuncture), even if the diagnosis is not yet confirmed, because the PPIQ-HU is not dependent on the diagnosis. The PPIQ-HU can also be used in comparative analyses and may provide clinical benefits. Additionally, it can be included as part of a test package, such as HADS, PCS, TSK, or GUPI, to create complex patient profiles.

Chronic pelvic pain is a common health issue affecting up to 25% of females of reproductive age worldwide 1 . In women, it is often characterized by persistent pain, although it can also be cyclical. The European Association of Urology defines chronic pelvic pain (CPP) as long-lasting or persistent pain felt in parts of the male or female pelvis and includes the suprapubic region, inguinal, urethral, penile clitoral, perineal, rectal, and back region, hips, and thigh regions 2 . CPP is defined by the Royal College of Obstetrics & Gynaecology (RCOG) as “an intermittent or constant lower abdominal pain of greater than 6 months duration, not occurring exclusively with menstruation or intercourse and not associated with pregnancy” 3 , 4 . According to the 2019 World Health Organization guidelines, all pain persisting for over three months is classified as chronic 5 , 6 . Chronic pelvic pain significantly affects daily life. It can affect one’s ability to sit comfortably, wear tight clothing, influence self-esteem, sexual relationships, and work. Additionally, chronic pelvic pain has considerable socioeconomic consequences 7 , 8 . A significant number of females, between 71 and 87%, experiencing chronic pelvic pain (CPP) have endometriosis lesions that can be identified through laparoscopy 9 and among those with CPP, between 40–and 87% are diagnosed with endometriosis, making it the most frequently identified cause of CPP among females 10 . Endometriosis is a chronic, -progressive disease characterized by endometrial-like tissue outside the uterus and is the most common underlying cause of chronic pelvic pain. Endometriosis-related pelvic pain is associated with different pain symptoms, such as dyspareunia, dysmenorrhea, dyschezia, and dysuria. These conditions have a significant impact on quality of life and both mental and physical health 11 . Endometriosis could be considered either a predisposing or perpetuating factor for chronic pelvic pain 12 . Several internationally available measurement tools assess the impact of pelvic pain. One such instrument is the Impact of Female Chronic Pelvic Pain Questionnaire (IF-CPPQ) 13 a comprehensive tool designed for in-depth psychological profiling. It evaluates the relational, occupational, sexual, and psychological effects of chronic pelvic pain in detail. In Hungary, the Australian Pelvic Floor Questionnaire (APFQ) 14 has been culturally adapted and validated to assess pelvic symptoms. To the best of our knowledge, no culturally adapted and validated Hungarian-language instrument currently exists—for instance, the Pelvic Pain Impact Questionnaire (PPIQ)—that specifically assesses the impact of chronic pelvic pain on the daily lives of women. PPIQ has been used in many different studies focusing on the impact of pelvic pain, and it was also used to measure the efficacy of a group physiotherapy program 15 . The PPIQ is a short and user-friendly questionnaire as it has only eight items with a 5-point Likert scale and two optional items, as it is a quick, short, and practical in clinical routine, diagnosis-independent so it can be used in a wide range of conditions, including endometriosis, vulvodynia, IBS, and CPP. It could also be integrated into multidisciplinary protocols in the future. So far, the recently developed PPIQ (Chalmers) has been translated into Turkish language 16 . It is important to have a self-administered, user-friendly questionnaire in clinical practice to assess the impact of pelvic pain because many patients feel uncomfortable discussing their symptoms. This questionnaire can be used to assess the impact of an intervention aimed at alleviating chronic pelvic pain and can contribute to further clinical studies and a better understanding of chronic pelvic pain in Hungary. To our knowledge, there is currently no measurement tool available in Hungarian to evaluate the effects of pelvic pain on everyday life. Therefore, in this study, we aimed to translate and culturally adapt the PPIQ (Pelvic Pain Impact Questionnaire) to Hungarian.