[Decrease in coronary heart disease mortality in 1974-1992 largely explainable by changes in cholesterol and smoking risk factors]

Abstract

Objective: To ascertain to what extent the dramatic decrease in coronary heart disease (CHD) mortality from 1972 to the present can be attributed to a change in risk factors.

Design: Descriptive study based on literature data.

Setting: The Netherlands.

Methods: Changes in four risk factors were assessed: a survey on trends in average systolic and diastolic blood pressure and serum cholesterol from three national screening projects, conducted 1974-1980, among 30,000 men and women aged 37-43 years, 1981-1986 among 80,000 men aged 33-37 years, and 1987-1992 among 42,000 men and women aged 20-59 years, and the percentage of smokers observed by the Foundation on Public Health and Smoking in yearly surveys among 20,000 people from the age of 15. Using a preventable proportion calculation, the effect on mortality was estimated of the observed changes in these risk factors, applying published relative risks and regression coefficients for these risk factors for men. The estimated curves were compared with the coronary mortality curves observed by the Netherlands Central Bureau of Statistics.

Results: From 1974 to 1992 a substantial decrease in the percentage of smokers and in men a moderate decrease in average serum cholesterol level were observed. Serum cholesterol decreased little in women. Changes in blood pressure were not consistent. The calculations predicted a 33% decrease in CHD mortality; the decrease actually observed was 48% for men aged 20-69 and 42% for women.

Conclusion: It appears that by far the largest proportion of the decrease in CHD mortality can be explained by a decrease in the values of relevant risk factors (cholesterol and smoking) and only a small part by improved therapy.