A study of the association between hormone replacement therapy, smoking and the occurrence of myocardial infarction in women

Abstract

The initial results are reported of a case-control study undertaken on the VAMP multi-purpose database and designed to estimate the risk for first-time occurrence of myocardial infarction in users of hormone replacement therapy (HRT). The findings currently available relate to the computerized data and show 2- to 5-fold increases in risk in smokers and those with diabetes mellitus, hypertension or hyperlipidaemia. With any form of HRT, a non-significant protective effect [adjusted odds ratio = 0.83 with 95% CI (confidence intervals) of 0.66-1.03, p = 0.089] has been shown. However, the protective effect of HRT in the data available to date appears to be confined to non-smokers in whom the odds ratio in the absence of other risk factors is 0.70 (95% CI of 0.49-1.00). The comparable odds ratio in smokers is 1.05 (95% CI of 0.71-1.53). These results should be interpreted with caution as smoking status was unknown for about half of the subjects and was more complete among the cases than controls.