Vaginal bleeding/spotting with conjugated estrogens/bazedoxifene, conjugated estrogens/medroxyprogesterone acetate, and placebo

In the 1-year phase 3 Selective estrogens, Menopause, And Response to Therapy-5 trial, cumulative amenorrhea rates with conjugated estrogens/bazedoxifene (CE/BZA) were similar to placebo and higher than with conjugated estrogens/medroxyprogesterone acetate (CE/MPA). This post hoc analysis reports bleeding/spotting rates in 4-week intervals (cycles) and 3-month intervals (quarters) with these therapies and the percentage of cases attributable to spotting only.

Generally healthy postmenopausal women with menopausal symptoms recorded vaginal bleeding/spotting in daily diaries while receiving CE 0.45 mg/BZA 20 mg, CE 0.625 mg/BZA 20 mg, CE 0.45 mg/MPA 1.5 mg, or placebo.

A total of 1596 women in the modified intent-to-treat population contributed data. Incidence of bleeding/spotting was significantly (p < 0.001) lower with CE 0.45 mg/BZA 20 mg (0.54‒4.44%), CE 0.625 mg/BZA 20 mg (1.26‒5.02%), and placebo (1.55‒4.82%) compared with CE 0.45 mg/MPA 1.5 mg (8.81‒25.63%) in all 4-week cycles. Each quarter, <10% of women taking CE/BZA doses or placebo had bleeding/spotting, significantly (p < 0.001) less than the 21-36% with CE 0.45 mg/MPA 1.5 mg. Odds ratio for bleeding/spotting with CE 0.45 mg/BZA 20 mg vs CE 0.45 mg/MPA 1.5 mg was 0.1 in each quarter (95% CI, Q1-Q3: 0.1-0.2; Q4: 0.1-0.3). Across all treatments, most (88-100%) bleeding/spotting cases were spotting only. Mean days of bleeding/spotting were <1 per quarter with CE/BZA doses and placebo, which was significantly (p < 0.01) less than the 3-5 days per quarter with CE/MPA.

Bleeding/spotting with CE/BZA treatment was similar to placebo and significantly less frequent than with CE/MPA treatment. Most cases were spotting only across all treatments.