Regional variation in ischemic heart disease incidence.

This study examines the relationship between cardiovascular risk factors and regional variation in IHD incidence among white males 55-74 years of age from the NHANES I Epidemiologic Followup Study. The age-adjusted IHD incidence rate was lowest in the west (31.3 per 1000 persons years of followup). The rates in the northeast, midwest, and south were similar and so they were combined into one region, the non-west, with a rate of 42.4. Differences in risk factors (smoking, educational level, hypertension, serum cholesterol, diabetes mellitus, and body mass index) did not explain the regional differences in IHD incidence. After adjusting for baseline risk factors using proportional hazards model, the risk of IHD incidence was still 38% higher in the non-west compared to the west. However, the effect of hypertension, diabetes, and body mass index on IHD incidence varied by region.