Relationship of risk factors to subsequent development of stroke and ischemic heart disease in a rural community.

A baseline examination of all residents aged 40 years and over, in the A-I district, Shibata City, Niigata Prefecture, Japan, was conducted in July 1977. The response rate for this examination was 84.5% for males and 92.6% for females. Nine hundred sixty males and 1,339 females, who were initially free from stroke, constituted the stroke cohort. Similarly 984 males and 1,342 females, who were free from myocardial infarction and angina pectoris on effort, made up the ischemic heart disease cohort. Both cohorts were followed for 10 years through June 1987. It is concluded that, in the agricultural community, the strongest risk factor for not only stroke but ischemic heart disease was hypertension, and that the attribution of hypercholesterolemia and obesity was small. The population that was studied experienced a period of relative economic deprivation before 1950, and there seems to be residual effects from this period to this day. The definition of cerebral infarction used in this study includes several pathologically different types (cerebral infarction of the cortical branches, cerebral infarction of the perforating branches, cerebral embolism and so on), and this may affect the results. On the other hand, the strongest risk factor for ischemic heart disease found in the A-I district is hypertension. This differs from the European/American type of ischemic heart disease, to which hypercholesterolemia and obesity are basic. These results also suggest the possibility that there is a difference not only etiologically but pathologically between the two types.