Efficacy and safety of dienogest in patients with endometriosis: A single-center observational study over 12 months

OBJECTIVE To evaluate the efficacy and safety of dienogest treatment in patients who had received dienogest for 12 months or more to treat endometriosis. METHODS We analyzed the clinical data of 188 women with endometriosis who had been treated with 2 mg of dienogest once a day for 12 months or more at a single institute. We evaluated changes in endometriosis-associated pain and endometrioma size, recurrence rate, and adverse events following dienogest administration. Bone mineral density (BMD) was measured in patients who were prescribed dienogest for more than 18 months. RESULTS Pain was significantly reduced at 12 months after dienogest medication. In those treated with dienogest due to recurrent endometrioma, the size of the endometrioma was significantly decreased at the 12-month and 18-month follow-ups. We found only one case of sonographic recurrence during dienogest administration among those who were treated postoperatively to prevent recurrence (1 of 114, 0.9%). The most common adverse drug reaction was uterine bleeding (3.2%), and other adverse events were generally tolerable and associated with low discontinuation rates (5.2%). Among the 50 patients in whom BMD was measured, 10 patients (20%) had a Z-score below the expected range for age. CONCLUSION The administration of dienogest for a year or more seems to be highly effective in preventing recurrence after surgery, reducing endometriosis-associated pain, and decreasing the size of recurrent endometrioma, with a favorable safety and tolerability profile. However, BMD should be checked in patients on long-term medication due to possible bone loss in some women.