SMOKING, SERUM-LIPIDS, BLOOD-PRESSURE, AND SEX-DIFFERENCES IN MYOCARDIAL-INFARCTION - A 12-YEAR FOLLOW-UP OF THE FINNMARK STUDY

Background Few epidemiological studies have investigated the relative importance of major coronary risk factors in the two sexes within the same study population. In particular, it is not clear whether smoking carries a similar risk of coronary heart disease in men and women. Met hods and Results The associations between smoking, serum lipids, blood pressure, and myocardial infarction were examined in a population-bas ed prospective study of 11843 men and women aged 35 to 52 years at ent ry. During 12 years, 495 cases of first myocardial infarction among me n and 103 cases among women were identified. Myocardial infarction inc idence was 4.6 times higher among men. The incidence was increased six fold in women and threefold in men who smoked at least 20 cigarettes p er day compared with never-smokers, and the rate in female heavy smoke rs exceeded that of never-smoking men. Multivariate analysis identifie d current smoking as a stronger risk factor in women (relative risk, 3 .3; 95% confidence interval [CI], 2.1 to 5.1) than in men (relative ri sk, 1.9; 95% CI, 1.6 to 2.3). Among those under 45 years old at entry, the smoking-related sex difference was more pronounced (in women: rel ative risk, 7.1; 95% CI, 2.6 to 19.1) (in men: relative risk, 2.3; 95% CI, 1.6 to 3.2). Serum total cholesterol, HDL cholesterol, and systol ic blood pressure were also highly significant predictors in both sexe s. Conclusions Smoking was a stronger risk factor for myocardial infar ction in middle-aged women than in men. Relative risks associated with serum lipids and blood pressure were similar despite large sex differ ences in myocardial infarction incidence rates.