Translation, cultural adaptation, and validation of the Portuguese version of ENDOPAIN-4D questionnaire

Background The endometriosis painful symptoms-4 dimensions ENDOPAIN-4D is a multidimensional questionnaire designed to assess endometriosis-related pain. This study aimed to translate, culturally adapt, and validate ENDOPAIN-4D for European Portuguese. Methodology Translation and content validity assessment were assessed in 32 women with endometriosis. For psychometric validation, 386 patients completed an online sociodemographic and clinical questionnaire, the Portuguese ENDOPAIN-4D, and the Endometriosis Health Profile Questionnaire-30 (EHP-30). Statistical analyses included descriptive statistics, exploratory factor analysis, internal consistency, item-total correlation, and concurrent validity.

Factor analysis of the “usual pain” dimension supported the original four-factor structure, accounting for 63.7% of variance (Cronbach’s α = 0.91). A novel three-factor structure was identified for the “worst pain” dimension, previously psychometrically untested, with good internal consistency (Cronbach’s α = 0.83) and acceptable item-total correlations. Concurrent validity with the EHP-30 ranged from weak to strong across domains.

The Portuguese ENDOPAIN-4D is a culturally adapted and validated instrument for multidimensional pain assessment in European Portuguese women with endometriosis, with validity likely limited for other Portuguese-speaking communities. The newly identified three-factor structure for worst pain may aid individualized pain management and follow-up in clinical and psychosomatic care. Further studies should evaluate concurrent validity and the stability and responsiveness of the new algorithms. Key messages The ENDOPAIN-4D enables multidimensional assessment of pain in women with endometriosis. The Portuguese version was translated, culturally adapted, and validated. The instrument showed excellent internal consistency and preserved factor structure. Further studies are needed to confirm concurrent validity and stability. This validation supports more patient-centered, evidence-based care in Portugal.

Endometriosis is a chronic inflammatory condition, characterized by the presence of endometrial tissue outside the uterus, affecting 5–10% of women of reproductive age [Citation1–4]. Its clinical spectrum is heterogeneous, ranging from asymptomatic cases to dysmenorrhea, chronic pelvic pain, dyspareunia, dysuria, dyschezia, infertility, and abnormal uterine bleeding, causing substantial physical, emotional, and social morbidity [Citation2,4–7]. Pain, reported in 80% of cases, and often incapacitating, is a primary reason women seek care, highlighting the importance of accurately characterizing symptomatology [Citation1,Citation2]. Endometriosis also imposes a significant economic burden estimated at €12.5 billion in Europe [Citation1]. Therefore, accurate characterization of pain symptomatology is crucial [Citation1]. Visual analogue scale (VAS) and numerical rating scale (NRS) are the most commonly used tools for general pain, including dysmenorrhea, deep dyspareunia, and chronic pelvic pain [Citation8]. However, these scales do not capture the heterogeneity of endometriosis-related pain, as individual symptoms involve multiple descriptors and their reporting can be influenced by both patients and clinicians [Citation9]. This highlights the need for multidimensional assessment tools for a more comprehensive evaluation. The Endometriosis Health Profile-30 (EHP-30) is a disease-specific questionnaire covering the impact of endometriosis on quality of life. Although it captures general pain, it does not fully access its multidimensional clinical characteristics, and its length and limited pain specificity may hinder routine clinical use [Citation5–7,10–12]. In response to these limitations, the ENDOPAIN questionnaire was developed by Arnaud Fauconnier with the support of the EndoFrance association in 2018 to assess the painful symptoms of endometriosis [Citation13]. Its psychometric validation was conducted by Anne Puchar (PhD) [Citation14]. The questionnaire has been recognized as a valuable tool for measuring endometriosis-related pain in clinical and research settings. The questionnaire, developed from patient testimonies, includes 21 items across four domains: spontaneous pelvic pain and dysmenorrhea, dyspareunia, painful bowel symptoms, and other symptoms. Each item is first assessed for symptom presence (Yes/No) and then for severity, distinguishing between usual and peak pain. Domain scores can be summed into a global pain score, while individual domain scores help guide targeted clinical interventions [Citation14–17]. The ENDOPAIN-4D provides a multidimensional assessment of endometriosis-related pain from the patient’s perspective [Citation18]. Originally developed in French and English, it has also been validated in Persian [Citation13,Citation14,Citation19]. To date, no tool exists for European Portuguese. This study presents the first cultural adaptation and psychometric validation of the ENDOPAIN-4D for European Portuguese speakers, enabling accurate assessment and international comparability. By converting the subjective symptom of pain into standardized clinical data [Citation8–13], the questionnaire offers a valuable tool for guiding personalized treatment strategies.

Authorization from the original ENDOPAIN-4D developers was obtained for its translation, cultural adaptation, and validation in Portuguese, marking its first use in Portugal. Intellectual property belongs to the Institute de Recherche en Sante de la Femme (IRSF). The adaption followed COSMIN (COnsensus-based Standards for the selection of health Measurement INstruments) guidelines [Citation13,Citation14], including dual translation, back-translation, expert review, and pre-testing. Authorization was also obtained to access the Portuguese EHP-30 for convergent validation [Citation5]. Translation and cultural adaptation The European Portuguese version was developed from the original English version. Two independent forward translations from English into Portuguese were performed by native speakers, one with a background in health sciences and the other without. Following review by an expert committee, the two versions were reconciled into a single translation, which was subsequently back-translated into English. The back-translations were compared with the original instrument, resulting in a preliminary Portuguese version. Pre-test A pretest was conducted with 32 participants to assess the comprehensibility and cultural adequacy of the Portuguese (Portugal) version of the ENDOPAIN-4D (Tables S1 and S2). This sample size was deemed sufficient for this type of instrument, considering disease prevalence (5–10%) [Citation20]. Due to logistical constraints associated with convening a group discussion with all participants, feedback was collected through an open-ended question included at the end of the questionnaire (“Would you change anything in this questionnaire?”). Feedback was analyzed descriptively, and cultural equivalence was considered acceptable when at least 80% of respondents reported no difficulty in understanding and answering the items, in accordance with Guillemin et al. [Citation21] Two participants indicated difficulties related to items referring to menstrual symptoms in the context of amenorrhea. As consultation with the original development team was not possible, two preliminary questions on uterine status and menstruation were added, along with instructions enabling participants to respond based on symptoms experienced even when items referred to menstruation. With 93.75% of participants reporting no difficulties, the questionnaire was deemed acceptable and finalized. Psychometric studies and validation The study received ethical approval. Participants were informed of the objectives, confidentiality, voluntary participation, and right to withdraw, and consent was obtained before completing the questionnaire. Sample and data collection The study was distributed via “MulherEndo” association. Eligible participants were Portuguese women aged ≥18 years with surgically or imaging-confirmed endometriosis. Exclusion criteria included gynaecological malignancy; major pelvic pathology; chronic pelvic pain unrelated to endometriosis; prior major pelvic surgery not related to endometriosis; or chronic diseases. The required sample size was based on Mesquita et al.’s recommendation of 10–15 participants per item, resulting in a minimum of 210–315 participants for the 21-item ENDOPAIN-4D [Citation22]. For reference, the original validation and the Persa translation included 220 and 169 participants, respectively. Data were collected online via self-administered questionnaires using Microsoft Forms®. All participants completed a sociodemographic and clinical questionnaire, the Portuguese versions of the ENDOPAIN-4D and EHP-30. Data collection occurred between August 28 and September 29, 2024, with 386 participants completing the questionnaires and included in the analysis. To ensure inclusion of only women with a confirmed diagnoses of endometriosis were included, warnings were displayed before and during the questionnaire emphasizing that participation was restricted to those with a confirmed diagnosis. Additionally, three verification questions were included, and participants providing inconsistent answers were excluded. The verification items were: “Beyond your symptoms, are you sure you have a CONFIRMED diagnosis of endometriosis by pelvic ultrasound, MRI, or surgery?”; “Which of the following examinations confirmed your diagnosis of endometriosis?”; and “In which country was the imaging examination or surgery confirming your diagnosis of endometriosis performed?”. Instruments ENDOPAIN-4D The ENDOPAIN-4D comprises 21-items divided into four dimensions: spontaneous pelvic pain and dysmenorrhea (items 1–10); dyspareunia (items 11–13); painful bowel symptoms (items 14–16); and other symptoms, such as dysuria, sciatica, right shoulder pain, and infertility (items 17–21). Each question is initially scored dichotomously (yes/no). If “yes,” the participant rates the symptom on a numerical scale from 0 (no pain) to 10 (worst pain imaginable). If “no,” a score of 0 is automatically assigned. For items referring to painful symptoms, participants rate both their usual pain and their worst pain experienced. Ten items assess painful symptoms, and eleven access the discomfort or emotional related impact of the pain [Citation14]. The sum of the items within each domain provides subscale scores, and the sum of these subscales yields the total score. The total score has a theoretical maximum of 170. The minimal clinically important difference (MCID) is 11 points [Citation13,Citation14]. Usual pain (in the past few months) reflects patients’ typical daily experience, while ‘worst pain’ captures peak episodes, allowing a comprehensive assessment of endometriosis-related pain intensity and variability. It should be noted that the algorithm developed by the original research team considered only usual pain, leaving the worst pain items unevaluated. The items included in the original algorithm are referred to as Part A, while those resulting from the development of a worst-pain algorithm are designated Part B. EHP-30 The EHP-30 is a self-administered questionnaire assessing quality of life in women with endometriosis. It comprises a 30-item core questionnaire, covering five dimensions (pain, control and powerlessness, emotional well-being, social support, and self-image) and a 23-item modular questionnaire evaluating six optional dimensions (work life, relationship with children, sexual relationships, healthcare providers, treatment, and infertility). Items are scored 0–4 (0 = never; 4 = always), and transformed to a 0–100 scale, with lower scores indicating better quality of life [Citation5,Citation12]. Statistical analysis Questionnaire validation followed COSMIN recommendations. Five criteria were used to assess psychometric properties: factor structure, internal consistency, item-total correlations, concurrent validity, and score distribution. Analyses were performed using the Statistical Package for the Social Sciences® (SPSS®), version 29.0). Descriptive analyses included frequencies, central tendency, and dispersion measures. Quantitative results are reported as mean ± standard deviation. Floor and ceiling effects were calculated, using a 70% threshold, as recommended by the instrument developers [Citation14] (Table S3). The factorial structure of the ENDOPAIN-4D, was examined using exploratory factorial analysis with principal components and Varimax rotation, preceded by KMO (Kaiser-Meyer-Olkin test) and Barlett tests. Factor loadings and communalities ≥0.4 and variance ≥60% were considered acceptable [Citation23], with KMO and Bartlett values ≥70% deemed satisfactory. Internal consistency was assessed via Cronbach’s α (≥0.7 acceptable, ≥0.8 good) and Item-total correlations ≥0.3 were considered acceptable [Citation23,Citation24]. Concurrent validity was evaluated using Pearson’s correlation (≥0.5 relevant) [Citation25]. Statistical significance was set at p < 0.05. Test-retest reliability was not assessed, in line with the original validation study, due to the fluctuating nature of pain symptoms in endometriosis [Citation26].

A total of 402 responses were collected, with 386 deemed valid. Participants had a mean age of 37.3 ± 7.8 years (range 20–55). Most women were married or cohabiting (61.1%) and 42.2% (n = 163) had a bachelor’s degree or higher. A large majority (90.4%, n = 349) were professionally active. Clinically, 47.7% (n = 184) reported comorbidities, mainly cardiovascular (13.5%; n = 52) and endocrine disorders. Regarding gynecological and obstetric history, 79.3% (n = 306) were sexually active, 45.6% (n = 176) had experienced pregnancy, 33.7% (n = 130) had at least one child, and 22.0% (n = 85) reported miscarriage. Amenorrhea was noted in 58.8% (n = 227), and 9.3% (n = 36) had a history of hysterectomy. For endometriosis, the majority had a surgical diagnosis (65.3%; n = 252) and had received treatment (63.5%; n = 245), with pharmacological interventions (60.6%; n = 184) being more common than non-pharmacological interventions (46.4%; n = 179) (). Descriptive statistics for ENDOPAIN-4D total and subscale scores are presented in Supplementary Table S4, and participants response distributions in Table S5 and Table S6. Exploratory factor analysis Exploratory factor analysis was conducted on Part A of the ENDOPAIN-4D (), including two additional items not in the original algorithm (items 20.1 and 21.2). In the original study, item 20.2 was excluded due to a floor effect, which is not observed here, and item 21.2 was excluded for conceptual non-correlation with the other items. However, item 21.2 was considered potentially relevant for interpreting pain/symptoms associated with endometriosis and was therefore included. The original ENDOPAIN-4D assumed uncorrelated factors and use Varimax rotation, as in this study. Although eigenvalues suggested a five-factor solution, a theory-guided exploratory factor analysis (EFA) was conducted to evaluate the empirical adequacy of the original four-factor model [Citation27] (Figures S1 and S2). This structure showed satisfactory factor loadings and interpretability, supporting the coherence of the theoretical framework. The KMO measure and Bartlett’s test indicated sampling adequacy (KMO = 0.90, p< 0.001). Item 21.2 showed low communality (0.19) and did not load adequately on any component; therefore, it was excluded from the analysis, in line with the original study. In the revised factor analysis, the KMO measure was 0.91 and Bartlett’s test was significant (p < 0.001), indicating sampling adequacy. All communalities were ≥0.40. A four-factor solution accounted for 63.7% of the variance. Most items loaded as expected, except for item 8.2. The final factor structure was: Factor 1 - Spontaneous Pelvic Pain (excluding item 8.2); Factor 2 - Other Symptoms (including item 8.2); Factor 3 - Dyspareunia; Factor 4 - Bowel Pain and/or Symptoms. A sub-analysis of participants diagnosed from 2020 onwards (n = 218) replicated the four-factor structure, accounting for 63.4% of the variance, confirming its robustness and stability in recently diagnosed women. An EFA with Varimax rotation was performed to develop an algorithm for Part B, which had not previously existed. Preliminary analysis highlighted a few challenges. Item 11.3 was the only item representing the original dyspareunia factor, but it loaded on a factor that lacked theoretical coherence. It was therefore excluded, and its low item-total correlation (<0.3) further supported this decision. A subsequent three-factor extraction was conducted, yielding KMO = 0.82 and and Bartlett’s test p 0.40, and a total variance explained of 67.46%. All items loaded strongly on the expected factors (): Factor 1 - Bowel Pain and/or Symptoms; Factor 2 - Other Symptoms; Factor 3 - Spontaneous Pelvic Pain. This analysis resulted in a newly developed algorithm for assessing worst pain. Item-total correlation Item-total correlations for both Part A and Part B ranged from 0.3 to 0.7, indicating good consistency. Concurrent validity Convergent validity was supported by correlations between the adapted Part A of the ENDOPAIN-4D and the EHP-30 domains (). Spontaneous Pelvic Pain correlated strongly with Pain (r = 0.67), Control and Powerlessness (r = 0.63), and Work Life (r = 0.60), but weakly with Sexual Relationships (r = 0.18). Dyspareunia correlated strongly with Sexual Relationships (r = 0.78) and weakly with the other domains (r = 0.21–0.23). Intestinal Pain and Other Symptoms showed moderate correlations with Pain, Control and Powerlessness, and Work Life, but weak correlations with Sexual Relationships ( and ).

This study translated, culturally adapted, and validated the ENDOPAIN-4D questionnaire into European Portuguese, providing a tool to assess the multidimensional nature of pain in women with endometriosis. Following COSMIN methodology, the process involved translation, back-translation, and pre-testing with 32 women, followed by validation. Data were collected via an online survey distributed through the “MulherEndo” association, yielding 402 responses, of which 386 were valid. The study sample had a mean age of 37.3 years, consistent with previously reported mean ages of women with endometriosis [Citation14,Citation19]. Regarding educational attainment, 42.2% of participants held a bachelor’s degree or higher, Detailed education data are not reported in the original ENDOPAIN-4D validation or the Persian translation, preventing direct comparison with our sample. Education levels, however, are broadly consistent with other endometriosis PROM validation studies, such as the Portuguese EHP-30 [Citation5]. Recruiting through a patient association may introduce selection bias, as participants could be more engaged and have higher health literacy. However, for psychometric validation, representativeness is less critical than ensuring adequate variability of the construct, and convenience samples are widely accepted [Citation28–30]. Recruitment was open to all eligible members, and similar strategies are commonly used in endometriosis validation studies. Residual selection bias, however, cannot be fully excluded. Although many participants completed the questionnaire years after treatment, recall bias is likely limited because the EndoPain-4D focuses on symptoms over the past few months [Citation14]. Nevertheless, we recognize that replicating the study with a more homogeneous sample would be relevant with respect to this aspect. Clinically, the distribution of comorbidities aligned with national data, with cardiovascular and endocrine diseases being the most prevalent [Citation31]. The high proportion of women reporting amenorrhea likely reflects the effects of commonly prescribed endometriosis treatments [Citation1]. Surgical diagnosis was most common, though imaging is increasingly incorporated into diagnostic pathways. Current guidelines support imaging as part of the diagnostic work-up, particularly for ovarian endometriomas and deep disease, while surgical confirmation remains the gold standard [Citation32,Citation33]. Notably, the original study also included imaging-based diagnoses in addition to surgical confirmation [Citation14]. Regarding treatment, 36.5% of women reported no ongoing therapy, a higher proportion than the 22% reported by Bourdon et al. [Citation34] This likely reflects the high number of recently diagnosed participants, which may result from increased medical and social awareness of endometriosis, improved diagnostic techniques, and greater engagement by newly diagnosed women [Citation35]. Collaboration with the “MulherEndo” association allowed access to a larger sample compared with both the original study and the Persian validation [Citation14,Citation19]. Using a patient-reported sample, based on self-report, not only enhanced nationwide recruitment and geographical representativeness but also ensured adequate variability for robust psychometric validation [Citation15,28–30]. While recruitment through a patient association may raise concerns about diagnostic reliability, the inclusion of three confirmatory items likely mitigated this risk. All ENDOPAIN-4D and EHP-30 items had >100 responses, with many exceeding 200 responses. Part A scores were lower than Part B, with pelvic pain–related disability highest, consistent with symptom patterns reported in the literature. [Citation4]. EHP-30 core scores exceeded 50, and the infertility domain showed the greatest burden, reflecting the substantial impact of endometriosis on quality of life. [Citation1,Citation4] In factor analysis of Part A, items 20.2 and 21.2 were initially included, despite their exclusion in the original study due to floor effect and conceptual mismatch, respectively. Item 21.2 was subsequently excluded because of low communality. The final analysis showed satisfactory psychometric indicators, including significant KMO and Bartlett’s tests, adequate communalities, and coherent factor loadings. Although the factor structure differed slightly from the original, the theoretical dimensions were preserved, and the explained variance (63.7%) supported construct validity. Cronbach’s α was 0.91, indicating high internal consistency. Although high values may rise concerns about item redundancy, concerns about redundancy generally arise only when inter-item correlations exceed 0.80 [Citation28,Citation29], which was not observed in this study, suggesting that the high α reflects internal consistency rather than item redundancy. Notably, except for item 8.2, all items loaded on their intended dimensions. The loading of Item 8.2 (“Pain spreads to the legs and hips”) onto the intestinal symptoms dimension is consistent with the theoretical construct of referred pelvic visceral pain commonly described in endometriosis. Pain arising from bowel and deep pelvic structures may radiate to the hips and lower limbs due to shared neural pathways and mechanisms of central sensitization. This pattern has been widely reported in the endometriosis literature and supports the interpretation of this factor as reflecting meaningful symptom clustering rather than item misalignment. Some discrepancies from the original French version, notably in the “other symptoms” domain, likely reflect the low incidence of “sciatic pain”, sample-specific characteristics, and cultural differences. Differences in recruitment compared with Puchar’s study may explain the emergence of a musculoskeletal dimension, possibly reflecting a broader sample including sensitization syndromes. Although imaging was used for diagnosis in both studies, the wider heterogeneity in our sample could contribute to musculoskeletal symptom reporting and the resulting factor structure. As this is the first adaptation of the ENDOPAIN-4D for Portuguese women, a theory-guided exploratory factor analysis was conducted, which is recommended when validating a scale in a new linguistic or cultural context [Citation27,Citation28]. These differences may reflect contextual or cultural factors affecting item interpretation, a common issue in scale adaptation. They do not compromise construct validity, but future research - such as confirmatory factor analysis based on the French structure - could further explore whether the original factor structure is replicable in the Portuguese context. For Part B, factor analysis was conducted to develop a new algorithm for assessing worst pain. Item 11.3 (dyspareunia) was removed due to multiple statistical issues, resulting in a three-factor solution with good fit: all items loaded adequately, the explained variance was 68.9%, and Cronbach’s α was 0.91. This algorithm enables assessment of worst pain and may support more personalized management of pelvic, bowel, and other symptoms, including dysuria, sciatica, and right shoulder pain. Future studies should consider conducting confirmatory factor analysis to verify the factor structure suggested by the exploratory analysis. To date, no other study in Portugal has used this scale with a different sample to confirm the proposed structure. Concurrent validity with the EHP-30 was assessed via Pearson’s correlation. The correlations observed between the ENDOPAIN-4D and the EHP-30 likely reflect that these instruments assess related but distinct constructs. While the ENDOPAIN-4D focuses specifically on pain characteristics, intensity, and distribution, the EHP-30 captures broader aspects of health-related quality of life, including emotional, social, and functional domains [Citation12,Citation14]. As pain represents only one of several determinants of quality of life in women with endometriosis, strong correlations between these measures are not necessarily expected. Additionally, differences in temporal focus and sample heterogeneity may further contribute to the observed correlation patterns. These findings therefore suggest acceptable concurrent validity while also supporting the discriminant value of the ENDOPAIN-4D. Finally, a test-retest assessment was not performed, in line with the original study, as pain fluctuations can produce artificially significant differences [Citation26]. The Portuguese ENDOPAIN-4D provides a multidimensional assessment of both usual and worst pain across symptom domains, contributing to more individualized clinical management. Further research is required to strengthen concurrent validity using instruments that specifically evaluate all ENDOPAIN-4D dimensions, as well as to confirm the performance of the newly proposed algorithms and their clinical correlations. This study did not evaluate the sensitivity to change of the ENDOPAIN-4D; therefore, its suitability for therapeutic evaluation remains to be established. Future studies should assess the responsiveness of the instrument in longitudinal and interventional settings.

This study represents the European Portuguese adaptation of the ENDOPAIN-4D; its validity in other Portuguese-speaking communities remains to be established, and future studies should evaluate its cross-cultural applicability. The instrument was translated, culturally adapted, and validated, allowing multidimensional assessment of pain in women with endometriosis. It is expected to improve the accuracy of pain evaluation in Portuguese women, ultimately supporting optimized treatment. Ethics approval and consent to participate The study was approved by the Ethics Committee for Research in Life and Health Sciences (Approval number: CEICVS 103/2024) and conducted in accordance with the Declaration of Helsinki. Participants provided electronic informed consent before completing the online questionnaire. Consent for publication Not applicable. Supplemental material Supplementary material Download MS Word (58.5 KB)Supplementary materialAcknowledgements The authors thank MulherEndo - Associação Portuguesa de Apoio a Mulheres com Endometriose for assisting with study dissemination and participant recruitment. They also thank Arnauld Fouconnier, designer of the EndoPain 4D Questionnaire, for his collaboration. Disclosure statement The authors declare no conflicts of interest. Data availability statement The datasets generated and/or analyzed during the current study are not publicly available due to containing sensitive personal information but are available from the corresponding author on reasonable request. Supplemental material Supplemental data for this article can be accessed at https://doi.org/10.1080/0167482X.2026.2643521. Additional information Funding

- Smolarz B, Szyłło K, Romanowicz H. Endometriosis: epidemiology, classification, pathogenesis, treatment and genetics (review of literature). Int J Mol Sci. 2021;22(19):10554. doi: 10.3390/ijms221910554 - Rempert AN, Rempert TH, Liu A, et al. A systematic review of the psychosocial impact of endometriosis before and after treatment. Reprod Sci. 2024;31:1828–1860. doi: 10.1007/s43032-024-01515-w - Taylor HS, Kotlyar AM, Flores VA. Endometriosis is a chronic systemic disease: clinical challenges and novel innovations. Lancet. 2021;397(10276):839–852. doi: 10.1016/S0140-6736(21)00389-5 - Gruber TM, Mechsner S. Pathogenesis of endometriosis: the origin of pain and subfertility. Cells. 2021;10(6):1381. doi: 10.3390/cells10061381 - Nogueira-Silva C, Costa P, Martins C, et al. Validation of the Portuguese version of the endometriosis health Profile-30 (EHP-30). Acta Med Port. 2015;28(3):347–356. doi: 10.20344/amp.5778 - Martins J, Ferreira G, Vilaça M, et al. Quality of life and sexual satisfaction in women with endometriosis: the moderator role of symptom severity. Psychol Sex. 2022;13(4):952–964. doi: 10.1080/19419899.2021.1943501 - Montanari E, Dauser B, Keckstein J, et al. Association between disease extent and pain symptoms in patients with deep infiltrating endometriosis. Reprod Biomed Online. 2019;39(5):845–851. doi: 10.1016/j.rbmo.2019.06.006 - Bourdel N, Alves J, Pickering G, et al. Systematic review of endometriosis pain assessment: how to choose a scale?Hum Reprod. 2015;30(7):1536–1551. - Fauconnier A, Staraci S, Huchon C, et al. Comparison of patient- and physician-based descriptions of symptoms of endometriosis: a qualitative study. Hum Reprod. 2013;28(10):2686–2694. doi: 10.1093/humrep/det310 - Capezzuoli T, Clemenza S, Sorbi F, et al. Classification/staging systems for endometriosis: the state of the art. GREM Gynecol Reprod Endocrinol Metab. 2020;01:14–22 [Accessed: Sep 2024] Available from: https://gremjournal.com/journal/01-2020/classification-staging-systems-for-endometriosis-the-state-of-the-art/ - Vincent K, Kennedy S, Stratton P. Pain scoring in endometriosis: entry criteria and outcome measures for clinical trials. Report from the art and science of endometriosis meeting. Fertil Steril. 2010;93(1):62–67. doi: 10.1016/j.fertnstert.2008.09.056 - Jones G, Kennedy S, Barnard A, et al. Development of an endometriosis quality-of-life instrument: the endometriosis health Profile-30. Obstet Gynecol. 2001;98(2):258–264. doi: 10.1016/S0029-7844(01)01433-8 - Fauconnier A, Staraci S, Daraï E, et al. A self-administered questionnaire to measure the painful symptoms of endometriosis: results of a modified DELPHI survey of patients and physicians. J Gynecol Obstet Hum Reprod. 2018;47(2):69–79. doi: 10.1016/j.jogoh.2017.11.003 - Puchar A, Panel P, Oppenheimer A, et al. The ENDOPAIN 4D questionnaire: a new validated tool for assessing pain in endometriosis. J Clin Med. 2021;10(15):3216. doi: 10.3390/jcm10153216 - Jones G, Jenkinson C, Kennedy S. Development of the short form endometriosis health profile questionnaire: the EHP-5. Qual Life Res. 2004;13(3):695–704. doi: 10.1023/B:QURE.0000021321.48041.0e - Nicolas-Boluda A, Oppenheimer A, Bouaziz J, et al. Patient-reported outcome measures in endometriosis. J Clin Med. 2021;10(21):5106. doi: 10.3390/jcm10215106 - Fauconnier A, Drioueche H, Huchon C, et al. Early identification of women with endometriosis by means of a simple patient-completed questionnaire screening tool: a diagnostic study. Fertil Steril. 2021;116(6):1580–1589. doi: 10.1016/j.fertnstert.2021.07.1205 - Rosenbloom BN, Di Renna T, Nella A, et al. Screening for endometriosis: a scoping review of screening measures that could support early diagnosis. BMC Womens Health. 2025;25:353. doi: 10.1186/s12905-025-03866-1 - Ahmadpour P, Jahangiry L, Bani S, et al. Validation of the Iranian version of the ENDOPAIN-4D questionnaire for measurement of painful symptoms of endometriosis. J Obstet Gynaecol. 2022;42(6):2341–2348. doi: 10.1080/01443615.2022.2049726 - Perneger TV, Courvoisier DS, Hudelson PM, et al. Sample size for pre-tests of questionnaires. Qual Life Res. 2014;24(1):147–151. doi: 10.1007/s11136-014-0752-2 - Guillemin F, Bombardier C, Beaton D. Cross-cultural adaptation of health-related quality of life measures: literature review and proposed guidelines. J Clin Epidemiol. 1993;46(12):1417–1432. doi: 10.1016/0895-4356(93)90142-N - Martins Mesquita E. A short guide on how to carry out validation of scales measuring health outcomes. Acta Med Port. 2023;36(11):695–697. doi: 10.20344/amp.20041 - Hair JF, Babin BJ, Black WC, et al. Multivariate data analysis. Boston: Cengage; 2019. - Nunnally JC, Bernstein IH. Psychometric theory. 3rd ed. New York: McGraw-Hill; 1994. - Mukaka MM. Statistics corner: a guide to appropriate use of correlation coefficient in medical research. Malawi Med J. 2012;24(3):69–71. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3576830/ - Tsang S, Royse C, Terkawi AS. Guidelines for developing, translating, and validating a questionnaire in perioperative and pain medicine. Saudi J Anaesth. 2017;11(5):80. doi: 10.4103/sja.sja_203_17 - Fabrigar LR, Wegener DT. Exploratory Factor Analysis In: Chapter 2, Requirements for and Decisions in Choosing Exploratory Common Factor Analysis. Oxford: Oxford University Press; 2012. pp. 19–38. - DeVellis RF. Scale development: theory and applications. 4th ed. Thousand Oaks (CA): Sage Publications; 2017. - Streiner DL, Norman GR, Cairney J. Health measurement scales: a practical guide to their development and use. 5th ed. Oxford: Oxford University Press; 2015. - Terwee CB, Prinsen CAC, Chiarotto A, et al. COSMIN methodology for evaluating the content validity of patient-reported outcome measures: a delphi study. Qual Life Res. 2018;27(5):1159–1170. doi: 10.1007/s11136-018-1829-0 - Direção-Geral da Saúde. 2024. Plano Nacional de Saúde 2021–2030: saúde sustentável: de tod@s para tod@s. Lisboa: DGS. [Accessed: Sep 2024]. Available from: https://pns.DGS.pt/files/2023/02/PNS2021-2030_Saude-da-Populacao-em-Portugal.pdf - Nisenblat V, Bossuyt PMM, Farquhar C, et al. Imaging modalities for the non-invasive diagnosis of endometriosis. Cochrane Database Syst Rev. 2016;2016(2):CD009591. doi: 10.1002/14651858.CD009591.pub2 - Becker CM, Bokor A, Heikinheimo O, et al. Guideline: endometriosis. Hum Reprod Open. 2022;2022(2):hoac009. doi: 10.1093/hropen/hoac009 - Bourdon M, Maignien C, Giraudet G, et al. Investigating the medical journey of endometriosis-affected women: results from a cross-sectional web-based survey (EndoVie) on 1,557 French women. J Gynecol Obstet Hum Reprod. 2023;53(2):102708. doi: 10.1016/j.jogoh.2023.102708 - Keilmann L, Beyer S, Meister S, et al. Trends among patients with endometriosis over a 7-year period and the impact of the COVID-19 pandemic: experience from an academic high-level endometriosis centre in Germany. Arch Gynecol Obstet. 2022;307(1):129–137. doi: 10.1007/s00404-022-06730-x