Hypertension, cigarette smoking, and the decline in stroke incidence in eastern Finland.

Finland has high rates of both cardiovascular disease and cardiovascular disease risk factors. We studied random samples of the population 30-59 years of age for risk factors in two provinces of eastern Finland in 1972 and 1977. We then followed both cohorts until 1985 through linkage with national hospital discharge and death certificate registers. The prevalence of hypertension and smoking in both provinces declined between 1972 and 1977, as did the stroke incidence in the 8-year period of follow-up of each cohort. We observed no differences in stroke incidence between the two provinces. The relative risk of stroke in the later period (1977-1985) was 0.71 and 0.58 for men and women, respectively, when compared with the earlier period (1972-1980). Overall, 28% of all stroke events could be attributed to hypertension, 17% to smoking, and 43% to these two factors jointly. The decrease in the prevalence of hypertension and smoking accounted for about 29% of the decline.