Different Characteristics of the Female Sexual Function Index in a Sample of Sexually Active and Inactive Women

Background: The Female Sexual Function Index (FSFI) is a widely used measurement tool to assess female sexual function along the six dimensions of desire, arousal, lubrication, orgasm, satisfaction, and pain. However, the structure of the questionnaire is not clear, and several studies have found high correlations among the dimensions, indicating that a common underlying "sexual function" factor might be present. Aim: To investigate whether female sexual function is best understood as a multidimensional construct or, alternatively, whether a common underlying factor explains most of the variance in FSFI scores, and to investigate the possible effect of the common practice of including sexually inactive women in studies using the FSFI. Methods: The sample consisted of 508 women: 202 university students, 177 patients with endometriosis, and 129 patients with polycystic ovary syndrome. Participants completed the FSFI, and confirmatory factor analyses were used to test the underlying structure of this instrument in the total sample and in samples including sexually active women only. Outcomes: The FSFI is a multidimensional self-report questionnaire composed of 19 items. Results: Strong positive correlations were found among five of the six original factors on the FSFI. Confirmatory factor analyses showed that in the total sample items loaded mainly on the general sexual function factor and very little variance was explained by the specific factors. However, when only sexually active women were included in the analyses, a clear factor structure emerged, with items loading on their six specific factors, and most of the variance in FSFI scores was explained by the specific factors, rather than the general factor. University students reported higher scores, indicating better functioning compared with the patient samples. Clinical Translation: The reliable and valid assessment of female sexual function can contribute to better understanding, prevention, and treatment of different sexual difficulties and dysfunctions. Strengths and Limitations: This study provides a rigorous statistical test of the structure of the FSFI and an explicit decision rule for categorizing sexually inactive women. Limitations include a lack of control over the circumstances of data collection. Conclusion: This study supports the use of the FSFI as a multidimensional measurement of female sexual function but highlights the need to establish clear decision rules for the inclusion or exclusion of sexually active and inactive respondents. Copyright (C) 2017, International Society for Sexual Medicine. Published by Elsevier Inc. All rights reserved.