Oral estrogen replacement therapy versus placebo for hot flushes: a systematic review

To examine the effectiveness of oral hormone replacement therapy (HRT) with regard to hot flushes and night sweats, which are vasomotor symptoms commonly experienced by menopausal women.

Double-blind, randomized, placebo-controlled trials of oral HRT for at least 3 months' duration and reporting vasomotor outcomes were identified using a search strategy developed by the Menstrual Disorders Group and Subfertility Group of the Cochrane Collaboration. Twenty-one trials meeting the selection criteria were included in the review. Study participants totalled 2511. Trial duration ranged from 3 months to 3 years.

There was a significant reduction in the weekly hot flush frequency for HRT compared with placebo (weighted mean difference -17.46, 95% confidence interval (CI) -24.72 to -10.21). This was equivalent to a 77% reduction in frequency (95% CI 58.2-87.5) for HRT relative to placebo. Symptom severity was also significantly reduced compared with placebo (odds ratio (OR) 0.13, 95% CI 0.08-0.22). Withdrawal for lack of efficacy occurred significantly more often with placebo therapy (OR 17.25, 95% CI 8.23-36.15). Withdrawal for adverse events, commonly breast tenderness, edema, joint pain and psychological symptoms, was not significantly increased for HRT (OR 1.38, 95% CI 0.87-2.21). In women who were randomized to placebo treatment, a 50.8% (95% CI 41.7-58.5) reduction in hot flushes was observed between baseline and the end of the study.

Oral HRT is highly effective in alleviating hot flushes and night sweats. Owing to the marked effect seen with placebo treatment, it is important to compare therapies purported to alleviate vasomotor symptoms with a placebo or an established therapy.