Progestins are commonly prescribed first-line drugs for endometriosis. High rates of non-response and intolerance to these drugs have been previously reported. However, no study to date has investigated the characteristics and comorbidities of the patients taking progestins in relation to treatment outcomes, thus identifying which patients will respond or tolerate the treatment is currently impossible. The purpose of this study, therefore, was to identify risk factors for non-response and discontinuation of Dienogest (DNG) in patients with endometriosis.
This is a retrospective cohort study including patients currently taking, or newly prescribed DNG for endometriosis-associated pain presenting in the Endometriosis Clinic of the University Hospital of Bern between Jan 2017 and May 2018. Patients with initiation of the treatment directly after a surgery for endometriosis were excluded. For all participants the symptoms and co-morbidities were documented. Effectiveness, tolerability and discontinuation of DNG were the primary endpoints. Univariate and multivariate binary logistic regression models were carried out to identify risk factors for non-response, intolerance and discontinuation of DNG.
Sufficient or excellent treatment response was reported by 85/125 (68%) patients. Genital bleeding during the DNG treatment was negatively [OR (95% CI): 0.185 (0.056, 0.610), p= .006] and rASRM endometriosis stages III and IV positively [OR (95%CI): 3.876 (1.202, 12.498), p=.023] correlated with DNG response. When accounting for exclusively pre-treatment factors, primary dysmenorrhea [OR (95%CI): 0.236 (0.090, 0.615), p= .003] and suspicion of adenomyosis [OR (95%CI): 0.347 (0.135, 0.894), p= .028] inversely correlated with DNG response while the latter also correlated with treatment discontinuation [OR (95%CI): 3.189 (1.247, 8.153), p= .015].
Genital bleeding during the DNG treatment and low rASRM stages are independent risk factors for DNG non-response. Prior to treatment initiation, primary dysmenorrhea and suspicion of adenomyosis correlate with DNG non-response. The results could assist the clinician firstly to provide detailed information to the patients prior to treatment initiation, secondly to identify and possibly modify in-therapy factors correlated to treatment effectiveness and lastly to switch treatment on time if needed.

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