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

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.

Keywords:

• Validity
• reliability
• endopain-4D
• endometriosis

Acknowledgements

The authors hereby wish to express our gratitude to all the participants in this study. We are also grateful to Arnaud Fauconnier, creator of the ENDOPAIN-4D, for giving us the permission to use the questionnaire and for giving methodological advices for the scoring methods.

Ethics approval and consent to participate

Ethical approval was obtained from Tabriz University of Medical Sciences (Ethics code: IR.TBZMED.REC.1398.986) and written informed consent was obtained from participants. All methods were performed in accordance with the Declaration of Helsinki.

Disclosure statement

The authors declare that they have no conflict of interest.

Additional information

Funding

The research protocol was approved & supported by Tabriz University of Medical Sciences. Funding sources did not play any role in the design of the study and collection, analysis, and interpretation of data.