Hormone therapy and cerebrovascular events:: a population-based nested case-control study

Objective: The relationship between postmenopausal hormone therapy (HT) and cerebrovascular disease has been examined in several epidemiological studies and clinical trials with conflicting results. The authors aimed to evaluate the association between the use of HT and the incidence of first cerebrovascular event. Design: The study cohort comprised 158,031 women 50 to 69 years old registered in the U.K. General Practice Research Database between 1991 and 1997. The authors conducted a nested case-control analysis using all 920 confirmed cases of cerebrovascular events identified during the follow-up (536 of transient ischemic attack [TIA]; 259 of ischemic stroke; 125 of hemorrhagic stroke) and 10,000 controls. Results: The odds ratios of TIA, ischemic stroke, and hemorrhagic stroke among women currently using HT were 1.48 (95% CI, 1.17-1.87), 1.12 (95% CI, 0.78-1.59) and 1.21 (95% CI, 0.76-1.93), respectively, compared to never users. The overall risk estimate for having a cerebrovascular event was 1.34 (95% CI, 1.11-1.61). The risk of TIA was greater (1.96) among women using high doses of estrogen (95% CI, 1.34-2.87). Conclusion: Overall, a small increased risk of stroke associated with HT use of comparable magnitude to the one observed in recent clinical trials was found. The increased risk was more apparent for TIA than for stroke and was greater at higher doses.