Ultra-low-dose estradiol and dydrogesterone: a phase III study for vasomotor symptoms in China.

Objective: This study aimed to evaluate the efficacy and safety of ultra-low-dose estradiol plus dydrogesterone for vasomotor symptoms in postmenopausal women in China (trial registration CTR20160689).

Methods: A total of 332 patients were randomized to continuous combined estradiol 0.5 mg + dydrogesterone 2.5 mg or placebo for 12 weeks. The primary efficacy endpoint was change in the number of hot flushes per day from baseline to end of treatment. Secondary efficacy endpoints included change in the number of moderate-to-severe hot flushes per day, menopausal symptoms from baseline and quality of life.

Results: Between baseline and end of treatment, change in the mean number of hot flushes per day was -5.9 (95% confidence interval [CI] - 6.6, -5.2) with estradiol + dydrogesterone and -4.5 (95% CI -5.1, -3.8) with placebo, with a mean difference of -1.4 hot flushes per day (95% CI -2.2, -0.7;  < 0.001). Significant differences in favor of estradiol + dydrogesterone were also observed in several secondary efficacy endpoints. The study treatment was well tolerated.

Conclusion: Continuous combined estradiol 0.5 mg + dydrogesterone 2.5 mg reduced hot flushes in postmenopausal women in China. This ultra-low-dose regimen provides an additional option for women experiencing the vasomotor symptoms of menopause. These data are consistent with previous results in other populations.