Effect of risk factors and changes in risk factors on coronary mortality in three cohorts of middle-aged people in eastern Finland.

The association of smoking, serum cholesterol, and blood pressure with coronary mortality and the contribution of changes in these risk factors to the decline in coronary mortality was assessed in three cohorts of middle-aged population examined in 1972, 1977, and 1982 in Eastern Finland. A total of 10,758 men and 11,112 women were included in this study. The follow-up time of each subject was 8 years. Age-adjusted coronary mortality decreased from 54 per 10,000 person-years in the 1972 cohort to 30 per 10,000 person-years in the 1982 cohort among men and from eight per 10,000 person-years to four per 10,000 person-years among women in the 1972 and 1982 cohorts, respectively. Concomitantly with the decrease in coronary mortality, there was a marked decrease in cardiovascular risk factors. Among men, the age- and geographic area-adjusted hazard rate ratio of coronary mortality between 1972 and 1982 cohorts was 0.52 (95% confidence interval (CI) 0.38-0.72). After further adjustment for smoking, serum cholesterol, and blood pressure, the hazard rate ratio was 0.74 (95% CI 0.54-1.02). Among women, the corresponding hazard rate ratios were 0.49 (95% CI 0.21-1.12) and 0.73 (95% CI 0.30-1.71), respectively. Therefore, it can be estimated that in both sexes nearly half of the decrease in coronary mortality hazard was associated with the changes in risk factors. The fall in serum cholesterol level among men and the decrease in blood pressure among women contributed most of the decrease in coronary mortality hazard.