A meta-analysis of 19 trials involving more than 40,000 women found strong evidence that postmenopausal hormone therapy (HT) has little if any benefit in primary or secondary prevention of cardiovascular disease (CVD). The authors of the report, published by the Cochrane Heart Group, caution that the findings “need to be carefully considered” and that “the same treatment offers benefits in some women, but harms in others.”
The goal of the meta-analysis was to assess whether HT afforded prevention of CVD in postmenopausal women and whether those affects differed for primary versus secondary prevention. Included in the analysis were randomized controlled comparisons of oral HT versus placebo or a no-treatment control with administration for a minimum of 6 months (range 7 months to 10.1 years). Most of the studies were performed in the United States and the mean age of participants was 60 years.
The authors noted that study quality overall was good, with low risk of bias and that findings from the three largest trials dominated. Evidence was high quality indicating that HT had no protective effects for either primary or secondary prevention of all-cause mortality, cardiovascular death, non-fatal myocardial infarction, angina, or revascularization. In the HT arm, however, risk of stroke was increased for combined primary and secondary prevention (RR 1.24, 95% CI 1.10-1.41). In comparison with placebo, HT also increased risk of risk of venous thromboembolism (VTE) (RR 1.92, 95% CI 1.36-2.69) and pulmonary emboli (RR 1.81, 95% CI 1.32-2.48).
Using a subgroup analysis, the authors also looked at the impact of when treatment was started in relation to menopause. Rates of mortality (RR 0.70, 95% CI 0.52-0.95) and coronary heart disease (CH) (RR 0.52, 95% CI 0.29-0.96) were lower in the women who started HT less than 10 years after menopause. However, they remained at increased risk of VTE (RR 1.75, 95% CI 1.11-2.73). Starting HT more than 10 years after menopause had little effect on death or CHD but risks of stroke (RR 1.21, 95% CI 1.06-1.38) and VTE (RR 1.96, 95% CI 1.37-2.80) were increased.