Coronary heart disease deaths in 25 years. The experience in the three Serbian cohorts of the Seven Countries Study.

Three cohorts of men aged 40-59 at entry examination were enrolled between 1962 and 1964 in the Serbian section of the Seven Countries Study of Cardiovascular Diseases. They were a sample in the rural village of Velika Krsna (n = 511), the workers in an agro-industrial cooperative in the city of Zrenjanin (n = 516), and the University professors of Belgrade (n = 536). At entry examination and then after 5 and 10 years, some cardiovascular risk factors were measured while the follow-up for mortality and causes of death was continued for 25 years. The 25 year standardized death rates from coronary heart disease (CHD) were higher in Zrenjanin (177 per 1000) and lower in Belgrade (118) and Velika Krsna (122). The multivariate prediction of CHD mortality by the Cox model in the lumped samples showed significant coefficients for age, body mass index, systolic blood pressure and cigarette consumption. The coefficient of serum cholesterol did not reach a statistically significant level. An unknown but significantly protective factor was identified for the Belgrade sample, likely bound to the higher social class of this group. Changes of systolic blood pressure in the first 10 years of follow-up were positively and highly related to the deaths occurred in the subsequent 15 years. The three population groups showed, between year 0 and year 10 follow-up, large increases in mean levels of blood pressure and mainly of serum cholesterol (+30 mg/dl in Velika Krsna; +36 mg/dl in Belgrade and +61 mg/dl in Zrenjanin). The sample in Zrenjanin started from intermediate levels (168.7 mg/dl) but attained the greatest increase and reached the highest CHD death rate in 25 years.