Risk factors and 25 year risk of coronary heart disease in a male population with a high incidence of the disease: the Finnish cohorts of the seven countries study.

OBJECTIVE: To assess the efficacy of high serum cholesterol concentration, raised blood pressure, and smoking as predictors of coronary heart disease.
DESIGN: Prospective cohort study of middle aged men conducted over 25 years.
SETTING: Finish components of an ongoing international study (seven countries study). PARTICIPANTS: 1520 Men who at age 40-59 in 1959 were free of clinically evident heart disease.
INTERVENTIONS: At each follow up visit a detailed medical examination including resting electrocardiography was performed, blood pressure and serum total cholesterol concentration were measured, and smoking was assessed.
MEASUREMENTS AND MAIN RESULTS: 825 Deaths (54% of participants) occurred during follow up, of which 335 were due to coronary heart disease. The hazard ratio for death from coronary heart disease with respect to risk factors at entry were: for serum cholesterol concentrations above 8.4 mmol/l v below 5.2 mmol/l, 2.68 (95% confidence interval 1.62 to 4.42); for systolic blood pressure in the highest quintile v that in the lowest quintile, 2.46 (1.72 to 3.50); and for smoking 10 or more cigarettes daily v never smoking, 1.95 (1.36 to 2.79). The hazard ratios with respect to cholesterol concentrations and blood pressure remained constant during follow up but the ratio with respect to smoking diminished, mainly owing to men giving up the habit. The estimated conditional probability of a 50 year old man dying of coronary heart disease in the next 25 years ranged from 12% among those with the most favourable risk factor profile to 75% among those with the least favourable profile.
CONCLUSIONS: High risk factor levels (as determined in this study) in middle aged men may greatly increase the absolute probability of death from coronary heart disease when the period of study is relevant to the human life span.