INTER-COHORT DIFFERENCES IN CORONARY HEART-DISEASE MORTALITY IN THE 25-YEAR FOLLOW-UP OF THE 7 COUNTRIES STUDY

Sixteen cohorts of men aged 40-59 years at entry were examined with th e measurement of some risk factors and then followed-up for mortality and causes of death for 25 years. These cohorts were located in the US A (1 cohort), Finland (2), the Netherlands (1), Italy (3), the former Yugoslavia (5), Greece (2), and Japan (2), and included a total of 12, 763 subjects. The differences in age-adjusted coronary heart disease ( CHD) death rates were found, with extremes of 45 per 1000 in 25 years in Tanushimaru, Japan, to 288 per 1000 in 25 years in East Finland. In general, higher rates were found in the US and Northern European coho rts as compared to the Southern European and Japanese cohorts. However , during the last 10 years of follow-up large increases of CHD death r ates were found in some Yugoslavian areas. Out of 5 measured entry cha racteristics treated as age-adjusted levels (serum cholesterol, systol ic blood pressure, cigarette smoking, body mass index and physical act ivity at work), only serum cholesterol was significant in explaining c ohort differences in CHD death rates. Over 50% of the variance in CHD death rates in 25 years was accounted for by the difference in mean se rum cholesterol. This association tended to decline with increasing le ngth of follow-up, but this was due to the great changes iri mean seru m cholesterol in the two Jugoslavian cohorts of Velika Krsna and Zrenj anin. When these two cohorts were excluded the association increased w ith time. Changes in mean serum cholesterol between year 0 and 10 help ed in explaining differences in CHD death rates from year 10 onward. I t can be concluded that this study suggests that mean serum cholestero l is the major risk factor in explaining cross-cultural differences in CHD.