Time to first occurrence of breast pain and vaginal bleeding in phase 3 trials of CE/BZA.

Objective: In studies of the menopausal therapy, conjugated estrogens/bazedoxifene, breast pain and vaginal bleeding rates were comparable to placebo and lower than conjugated estrogens/medroxyprogesterone acetate (MPA). This post hoc analysis determined median time to occurrence of these events.

Methods: Participants in phase 3 conjugated estrogens/bazedoxifene trials recorded breast pain and vaginal bleeding in daily diaries. Median time to first incident was determined in women taking conjugated estrogens 0.45 mg/bazedoxifene 20 mg, conjugated estrogens 0.625 mg/bazedoxifene 20 mg, placebo, and conjugated estrogens 0.45 mg/MPA 1.5 mg (active control in Selective estrogens, Menopause, And Response to Therapy [SMART]-5 trial). We included on-treatment data (12 weeks-2 years) in healthy postmenopausal women (SMART-1), those seeking treatment for menopausal symptoms (SMART-5), and those with moderate/severe vasomotor symptoms (SMART-2). Analyses were performed using SAS Proc Lifetest.

Results: With conjugated estrogens/MPA as comparator, median time to breast pain was 299 days for conjugated estrogens/MPA, 353 for placebo, and more than 365 (median not reached) for conjugated estrogens 0.45 mg/bazedoxifene 20 mg and conjugated estrogens 0.625 mg/bazedoxifene 20 mg. Median time to vaginal bleeding was 314, 341, 357, and 362 days, respectively. Breast pain and vaginal bleeding survival curves were not significantly different for conjugated estrogens/bazedoxifene and placebo in any study, but were (P < 0.0001) when conjugated estrogens/MPA was added to the sample in SMART-5.

Conclusions: The time course of breast pain and vaginal bleeding with conjugated estrogens/bazedoxifene was similar to that of placebo during treatment for up to 2 years. Events occurred significantly earlier with conjugated estrogens/MPA versus conjugated estrogens/bazedoxifene or placebo.