How can we measure endometriosis-associated pelvic pain?

Purpose: The aim of our work was to explore which of the most commonly used pain scales is best suited to assess treatment success in endometriosis therapy and, therefore, qualifies best to be used as primary endpoint for clinical studies in this indication. Methods: We compared patient's responses on the different pain scales Visual Analog Scale, Biberoglu and Behrman Score, and SF-36 Bodily Pain Subscale with the Clinical Global Impression score. Parametric and non-parametric correlation coefficients and effect sizes were calculated. Results: A total of 428 patients with endometriosis-associated pelvic pain from three studies were included in our analyses. Their mean age was 31.4 +/- 6.3 years and their mean pain score on the visual analog scale was 58.1 +/- 21.9 at baseline. The highest correlation with the Clinical Global Impression score was observed for the visual analog scale followed by the B&B pelvic pain item. The highest effect sizes were found for dysmenorrhea and SF-36 bodily pain subscale followed by the visual analog scale. Conclusions: A general measure of endometriosis-related pain can be recommended as primary endpoint in clinical trials to assess painful symptoms of endometriosis. In addition, a disease-specific quality of life tool is recommended to help interpret impact on patients' daily activities.