Measurement properties of sexual function assessment questionnaires in women with endometriosis: A systematic review following COSMIN guidelines

Introduction: Sexual function of patients with endometriosis should be assessed by patient-reported outcome measures (PROMs) that present high reliability and validity. The objective was to study the PROMs used to assess sexual function for patients with endometriosis to improve their selection for research and clinical practice.Material and methods: We performed a systematic literature review from January 2000 to September 2023. All studies including women with confirmed endometriosis and assessing sexual quality of life or sexual function or sexual distress were retrieved. Different properties of PROMs used for sexual dysfunction were assessed according to the COnsensus-based Standards for the selection of health Measurement Instruments (COSMIN) recommendations. Properties evaluated were: structural validity, internal consistency, cross-cultural validity, reliability, measurement error, criterion validity, construct validity, and responsiveness. This literature review was registered on Prospero as 2018 CRD42018102278.Results: Seventy-four articles with evaluation of sexual function were included. Of the 25 PROMs assessing sexual function, the Female Sexual Function Index (FSFI) was the most frequently used (34/74 [45.9%] items), followed by the Female Sexual Distress Scale (9/74 [12.2%] items) and the Sexual Activity Questionnaire (SAQ) (8/74 [10.8%] items). The most commonly used measurement properties were "hypothesis testing" and "responsiveness". The PROMs with a high level of evidence for these two measurement properties were the FSFI, the SAQ, the Short Sexual Functioning Scale, the Sexual Satisfaction Scale for Women, Sexual Quality of Life-Female, the Brief Profile of Female Sexual Function, and the Sexual Health Outcomes in Women Questionnaire. The FSFI questionnaire appeared to be more relevant for evaluating medical treatment, and the SAQ for evaluating surgical treatment. Only one instrument was specific to endometriosis (the Subjective Impact of Dyspareunia Inventory [SIDI]).Conclusions: In this systematic literature review of sexual function assessment questionnaires in endometriosis, the FSFI and the SAQ questionnaires emerged as having the best measurement properties according to the COSMIN criteria. The FSFI questionnaire appears to be suited for evaluating medical treatment, and the SAQ for surgical treatment. The SIDI is the only specific questionnaire, but its responsiveness remains to be defined.