Advancing the hypothesis that geographic variations in risk factors contribute relatively little to observed geographic variations in heart disease and stroke mortality

PurposeGeographic variation in risk factors may underlie geographic disparities in coronary heart disease (CHD) and stroke mortality.MethodsFramingham CHD Risk Score (FCRS) and Stroke Risk Score (FSRS) were calculated for 25,770 stroke-free and 22,247 CHD-free participants from the REasons for Geographic And Racial Differences in Stroke cohort. Vital statistics provided age-adjusted CHD and stroke mortality rates. In an ecologic analysis, the age-adjusted, race–sex weighted, average state-level risk factor levels were compared to state-level mortality rates.ResultsThere was no relationship between CHD and stroke mortality rates (r = 0.04; p = 0.78), but there was between CHD and stroke risk scores at the individual (r = 0.68; p < 0.0001) and state (r = 0.64, p < 0.0001) level. There was a stronger (p < 0.0001) association between state-level FCRS and state-level CHD mortality (r = 0.28, p = 0.18), than between FSRS and stroke mortality (r = 0.12, p = 0.56).ConclusionsWeak associations between CHD and stroke mortality and strong associations between CHD and stroke risk scores suggest that geographic variation in risk factors may not underlie geographic variations in stroke and CHD mortality. The relationship between risk factor scores and mortality was stronger for CHD than stroke.