Longitudinal changes in menopausal symptoms comparing women randomized to low-dose oral conjugated estrogens or transdermal estradiol plus micronized progesterone versus placebo: the Kronos Early Estrogen Prevention Study.

Objective: The objective of the present study was to compare the efficacy of two forms of menopausal hormone therapy in alleviating vasomotor symptoms, insomnia, and irritability in early postmenopausal women during 4 years.

Methods: A total of 727 women, aged 42 to 58, within 3 years of their final menstrual period, were randomized to receive oral conjugated estrogens (o-CEE) 0.45 mg (n = 230) or transdermal estradiol (t-E2) 50 μg (n = 225; both with micronized progesterone 200 mg for 12 d each mo), or placebos (PBOs; n = 275). Menopausal symptoms were recorded at screening and at 6, 12, 24, 36, and 48 months postrandomization. Differences in proportions of women with symptoms at baseline and at each follow-up time point were compared by treatment arm using exact χ tests in an intent-to-treat analysis. Differences in treatment effect by race/ethnicity and body mass index were tested using generalized linear mixed effects modeling.

Results: Moderate to severe hot flashes (from 44% at baseline to 28.3% for PBO, 7.4% for t-E2, and 4.2% for o-CEE) and night sweats (from 35% at baseline to 19% for PBO, 5.3% for t-E2, and 4.7% for o-CEE) were reduced significantly by 6 months in women randomized to either active hormone compared with PBO (P < 0.001 for both symptoms), with no significant differences between the active treatment arms. Insomnia and irritability decreased from baseline to 6 months postrandomization in all groups. There was an intermittent reduction in insomnia in both active treatment arms versus PBO, with o-CEE being more effective than PBO at 36 and 48 months (P = 0.002 and 0.05) and t-E2 being more effective than PBO at 48 months (P = 0.004). Neither hormone treatment significantly affected irritability compared with PBO. Symptom relief for active treatment versus PBO was not significantly modified by body mass index or race/ethnicity.

Conclusions: Recently postmenopausal women had similar and substantial reductions in hot flashes and night sweats with lower-than-conventional doses of oral or transdermal estrogen. These reductions were sustained during 4 years. Insomnia was intermittently reduced compared with PBO for both hormone regimens.