MYOCARDIAL-INFARCTION AND USE OF LOW-DOSE ORAL-CONTRACEPTIVES - A POOLED ANALYSIS OF 2 US STUDIES

Background-Population-based case-control studies to assess the relatio nship of low-dose oral contraceptive (OC) use with myocardial infarcti on (MI) were performed at 2 sites in the United States (California and Washington state). The purpose of the present study was to estimate r isk of MI in relation to use of low-dose OCs in a pooled analysis comb ining results from the 2 sites. Methods and Results-The study included as cases women aged 18 to 44 years with incident MI who had no prior history of ischemic heart disease or cerebrovascular disease. Women in the case and control groups were interviewed in person regarding OC u se and cardiovascular risk factors. The analysis included 271 MI cases and 993 controls. Compared with noncurrent users, the adjusted pooled odds ratio for MI in current OC users was 0.94 (95% CI, 0.44, 2.20) a fter adjustment for major risk factors and sociodemographic factors. C ompared with never users, the adjusted pooled odds ratio for MI was 0. 56 (0.21, 1.49) in current OC users and 0.54 (0.31, 0.95) in past OC u sers. Among past OC users, duration and recency of use were unrelated to MI risk as was current hormone replacement therapy. There was no ev idence of interaction between OC use and age, presence of cardiovascul ar risk factors (hypercholesterolemia, hypertension, diabetes), obesit y, or smoking. Conclusions-We conclude that low-dose OCs as used in th ese populations are safe with respect to risk of MI in women.