Sex differences in preinfarction characteristics and longterm survival among patients with myocardial infarction.

The prevalence of primary risk factors, previous medical history, and physical activity were assessed among 262 women and 1259 men who suffered a first nonfatal myocardial infarction between 1968 and 1977 in Göteborg, Sweden. The probability of suffering a myocardial infarction based on the conventional factors cholesterol level, systolic blood pressure and smoking habits was estimated in both sexes by means of a multiple risk function. Comparisons between sexes were made with age alone and age and estimated primary risk as confounders. Survival rate and reinfarction rate were calculated for a 5-year period of follow-up. Women with infarctions had higher serum cholesterol levels (p less than 0.001) and higher blood pressure values (p less than 0.001) but were less often smokers than men (p less than 0.001). The female patients also reported chest pain and dyspnea on exertion, and low physical activity both at work and during leisure time significantly more often than men; these differences remained after controlling for estimated primary risk. An overrepresentation of hypertension and diabetes prior to myocardial infarction was found among women below 45 years of age compared with men. A high frequency of women in this age group was also on sick leave or disability pension at onset of myocardial infarction, suggesting that mainly women with several risk factors including socioeconomic factors suffer an infarction at this age. No similar and consistent differences were found between women and men of older ages. The cumulative 5-year survival rate was 80% in women and 81% in men. Below age 45 the survival rate was lower among women than men (p less than 0.01). No sex difference was found in the recurrence rate of nonfatal reinfarctions. This indicates that once women have suffered a myocardial infarction they are exposed to at least as high a risk as men.