Dienogest 2 mg per day is effective and safe in the long-term management of endometriosis-associated pelvic pain (EAPP) in Chinese women with endometriosis along with a progressive decrease in EAPP and bleeding irregularities during the continued treatment, as evident from a study published in Journal of Women's Health.

Dienogest showed greater reduction in EAPP than the placebo in a 24-week, randomized, double-blind study of Chinese women with endometriosis. Qi Yu and the investigators performed an open-label extension study to examine the efficacy and safety of dienogest for 28 additional weeks in these women. Two hundred and twenty women with endometriosis were eligible to register after the 24-week, placebo-controlled study. The earlier treatment was not considered and all women received dienogest 2 mg per day for up to 28 weeks. The bleeding pattern, laboratory parameters, absolute change in EAPP from baseline on a 1–100 mm visual analog scale (VAS), adverse events (AEs) and bone mineral density (BMD) were analysed.

A total of  203 (92.3%) women completed the study. Mean (SD) change from baseline in EAPP score on VAS was −43.1 mm (26.54 mm) and −39.8 mm (31.15 mm) in the prior-dienogest and prior-placebo groups. According to other assessments, dienogest enhanced the efficacy of additional treatment after 28 weeks. Dienogest initiation was concerned with more extended, but fewer, spotting/bleeding episodes. During the continued treatment, bleeding frequency and intensity decreased progressively. Two (0.9%) patients withdrew the study due to mild or moderate treatment-emergent AEs. Dienogest portrayed no effect on the BMD. The safety and efficacy results of this study were in accordance with the previous studies in Caucasian patients.