[Hormone replacement therapy in menopause and the risk of cerebrovascular accident]

Hormone replacement therapy relieves climacteric symptom and prevents postmenopausal osteoporosis. A protective effect of estrogen against coronary heart disease remains debatable and inconclusive results have been reported with respect to the risk of stroke. We have therefore performed an updated quantitative assessment of the risk for stroke associated with hormone replacement therapy.

MEDLINE database was used. Studies analyzing postmenopausal women and considering any subtypes of stroke--i.e. fatal or non-fatal, ischaemic or haemorrhagic--as the outcome of interest were selected. An overall estimate was calculated as a weighted average of the odds ratios or relative risks, with the weights being the reciprocal of their variance. Random effects models were used to take into account the heterogeneity of data.

Six case-control studies, seventeen cohort studies and one randomized trial were selected between 1978 and 1998. Seven studies assessed the risk of ischaemic stroke associated with hormone replacement therapy and the pooled estimate of the risk was 1.12 (95% confidence interval, 1.01 to 1.25). The random effects model showed an increased risk of 18% (relative risk 1.18, 95% confidence interval, 0.98 to 1.43). Regarding haemorrhagic stroke, the analysis based on two case-control studies and one cohort study showed a significantly reduced risk of 35%. Lastly, based on five studies, no significant change in the risk of subarachnoidal hemorrhage was found.

This updated analysis suggests an increased risk for ischaemic stroke among postmenopausal women who use oral estrogen replacement therapy. No data regarding transdermal estrogen are available.