Validation of the Iranian version of the ENDOPAIN-4D questionnaire for measurement of painful symptoms of endometriosis

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