The trend of coronary heart disease and its risk factors based on epidemiological investigations.

Changes in the incidence of coronary heart disease (CHD) in the past 20 years have been observed in workers in the city and residents in rural areas and the risk factors of CHD studied. Findings show that the incidence of CHD in the residents in rural areas has hardly changed, and remains still low. However, the incidence of CHD in workers in the city has recently shown a tendency to increase. Furthermore, a study of CHD risk factors shows that in the rural areas residents hypertension has a strong influence on the incidence of CHD, while the role of serum total cholesterol is weak. In the city workers a high serum total cholesterol has become a risk factor. Therefore, it appears that the incidence of CHD caused by hypertension and by hypercholesterolemia are mixed in Japan. At present it appears that the influence of hypertension is becoming weaker, while the influence of hypercholesterolemia is becoming stronger. The resulting balance between them may be expressed as a rise and fall of CHD in Japan at present.