OBJECTIVE: To explore variability in patient-reported pain and potential differential treatment response in clinical studies among patients with endometriosis.
METHODS: Data came from two clinical studies of daily oral dienogest for treatment of endometriosis: study 307041 (dienogest 2 mg / day arm only over 12 weeks; n=102); and study 97085 (dienogest 2 mg / day versus leuprorelin acetate 3.75 mg / 4 weeks over 24 weeks; n=252). Heterogeneity of patient responses on the Bodily Pain (BP) domain of the SF-36v2 at both baseline and the follow-up time point were analysed using latent transition analysis (LTA) regardless of treatment group. The model combined cross-sectional measurement of latent (i.e., unobserved) variables and the longitudinal description of change in the latent variable over time. The latent-class variables identified data-driven subgroups based on the similarity of responses on the BP domain. One latent-class variable was identified for the baseline time point; a second latent-class variable was identified for the follow-up time point. Demographic and clinical characteristics were investigated between identified subgroups.
RESULTS: Large variability around mean BP was observed in both trials. In study 97085, 4 potential subgroups with differential response were identified: 3 of these showed improvement across the 24-week period (mean improvement range = 10.8 to 52.7) and were comprised of 92% of patients (n=232); the remaining 8% (n=16) showed a reduction (worsening) of BP scores from a mean (SD) of 36.9 (23.4) to 24.1 (11.5). In study 307041, 2 subgroups were identified: all patients improved across the 12 week period (mean improvement range: 12.3 to 45.2). Variables that were significantly related to subgroup membership included endometriosis-associated pelvic pain and concomitant analgesic use.
CONCLUSIONS: While variability in treatment response is high, pain was relieved for most patients. Presence and causality of differential response to endometriosis treatments require more research including cross-over studies.
