LAUSR

Abstract Endometriosis is one of the leading gynecological disorders in reproductive ages. About two-thirds of women with endometriosis experience chronic pelvic pain. There are different methods for the assessment of pain in endometriosis. One of these questionnaires is endometriosis painful symptoms-4 dimensions (ENDOPAIN-4D) questionnaire, which has not been validated in Iran. Therefore, we decided to conduct a study to determine the psychometric properties of this questionnaire. In this study, we randomly selected 169 women with endometriosis from two educational-medical centres of Al-Zahra and Taleghani in Tabriz, Iran, in 2020. We evaluated the validity of ENDOPAIN-4D in terms of face, content, and structure (through exploratory and confirmatory factor analyses). We used internal consistency assessment and test-retest reliability to determine the questionnaire reliability. In this study, the CVI and CVR for the ENDOPAIN-4D instrument were obtained as 0.99 and 0.98, respectively. In the exploratory factor analysis, we extracted a four-factor structure, and the confirmatory factor analysis gave a good fit for the extracted model. We obtained Cronbach's alpha coefficient as 0.96 and the intra-class correlation coefficient (ICC) (at 95% confidence interval) as 0.94 (0.85 to 0.98). The Persian version of ENDOPAIN-4D has acceptable content validity, construct validity and reliability for the evaluation of pelvic pain and gynaecology in Iranian women with endometriosis. Impact Statement What is already known on this subject? There are different methods for the assessment of pain in endometriosis. But there is no specific psychometric instrument to determine the painful symptoms of endometriosis in Iran so far. What do the results of this study add? The Persian version of ENDOPAIN-4D is a valid and reliable instrument for the evaluation of pelvic pain and gynaecology in Iranian women with endometriosis. What are the implications of these findings for clinical practice and/or future research? The validation of the Persian version of the ENDOPAIN-4D questionnaire leads to correct assessment of painful symptoms in Iranian women with endometriosis and will be useful in evaluating the patients' pain intensity and the response to treatment in practice.