Validation of the Sexual Activity Questionnaire in women with endometriosis

Is the Sexual Activity Questionnaire (SAQ) a valid tool for patients treated for symptomatic endometriosis?

For women having surgical treatment for endometriosis, we determined that the SAQ is a valid and responsive tool.

Endometriosis adversely affects sexual quality of life. Suitable validated sexual quality of life instruments for endometriosis are lacking both in clinical practice and for research.

A total of 367 women with proven endometriosis undergoing medical or surgical treatment were included in an observational study conducted between 1 January 2012 and 31 December 2014 in two French tertiary care centers. Both hospitals are reference centers for endometriosis treatment. Of these 367 women, 267 were sexually active and constituted the baseline population.

Women >18 years old with histological or radiological proven endometriosis, consulting for painful symptoms of at least 3 months duration, infertility, or other symptoms (bleeding, cysts) were invited to complete self-administered questionnaires before (T0) and 12 months after treatment (T1). Tests of data quality included descriptive statistics of the data, missing data levels, floor and ceiling effects, structural validity and internal consistency.The construct validity was obtained by testing presupposed relationships between previously established SAQ scores and prespecified characteristics of the patients by comparing different subgroups of patients at T0. Sensitivity to change was subsequently calculated by comparing the SAQ score between T1 and T0 overall and for different subgroups of treatment. Effect sizes (to T1) were calculated according to Cohen's method. The minimally important difference was estimated by a step-wise triangulation approach (including anchor-based method).

In total, 267 sexually active patients (204 surgical and 63 medical treatment) completed the SAQ at T0 and 136 (50.9%) at T1. The SAQ score ranged from 2.0 to 28.0 (mean ± SD: 16.8 ± 5.7).The SAQ score was one-dimensional according to the scree plot with good internal consistency (Cronbach alpha = 0.78, 95% CI 0.74-0.81) and had good discriminative ability according to pain descriptors and quality of life in endometriosis. The SAQ was responsive in patients treated by surgery but the effect size was low (0.3, 95% CI (0.0-0.6), P = 0.01). The minimally important difference was determined at 2.2.

The effect size for medical treatment was non-significant. Other effect sizes were low but statistically significant. This could be explained by lower libido due to progestin intake, which was used for both surgically and medically treated patients.

The SAQ is easy to use, valid and effective in assessing sexual quality of life in patients with endometriosis. This patient-reported score could be used as a primary outcome for future clinical studies. The minimally important difference estimation will be useful for future research. We recommend using 2.2 for the minimally important difference of the SAQ.

This work was funded by the 'Direction à la Recherche Clinique et à l'Innovation' of Versailles, France and the 'Institut de Recherche en Santé de la Femme' (IRSF). The authors have no conflicts of interest to declare.