Challenges in measuring sleep quality among women with endometriosis: A comparison of two questionnaires

Objective: This study aimed to underscore the issues associated with the dichotomization of categories in sleep questionnaires among women diagnosed with endometriosis and sleep disturbances, as well as their potential impact on the validity of the research findings.

Background: A range of questionnaires is employed across settings from primary care to research to classify sleep disturbances. Insomnia Severity Index (ISI) and the Pittsburgh Sleep Quality Index (PSQI) are two frequently utilized instruments for evaluating sleep. Nonetheless, these tools may produce divergent outcomes when applied to the same population.

Methods: To evaluate the sleep quality of patients with deep endometriosis (DE), two self-administered questionnaires were utilized: ISI and PSQI. Patients rated their average pelvic pain over the preceding four weeks on a numeric rating scale (NRS) ranging from 0 to 10. Patients with an ISI score >14 or PSQI >5 were classified as poor sleepers, while the others as good sleepers.

Results: Among the 161 patients who completed both sleep questionnaires, 129 (80 %) rated their subjective sleep quality as good. However, when the scores from the sleep questionnaires were analyzed, only 17 (11 %) patients were classified as good sleepers by the PSQI, whereas the ISI classified 83 (52 %) patients as good sleepers. When comparing the standardized scores, moderate to good reliability was found (intraclass correlation coefficient, 0.76; 95 % confidence interval, 0.69-0.82).

Conclusion: Both questionnaires yield consistent scores that seem comparable in women with DE; however, the cutoff values seem inadequate for this population. Therefore, we can probably rely on both questionnaire scores, yet their recommended cutoff values should be approached with caution.