Geographic variation in stroke risk in the United States - Region, urbanization, and hypertension in the Third National Health and Nutrition Examination Survey

Background-In the United States, stroke mortality is higher in the south th an in other regions. Hypertension is the main risk factor for stroke among older adults; however, few studies have examined group-specific regional an d urbanization differences in hypertension prevalence. Methods-Data from the Third National Health and Nutritional Examination Sur vey (NHANES III), 1988 to 1994, were analyzed to calculate the prevalence o f hypertension (systolic >140 mm Hg and/or diastolic >90 mm Hg and/or takin g antihypertensive medication) by region and urbanization for age (40 to 59 and 60 to 79 years), sex, and ethnic subgroups. Logistic regression models were fitted to estimate the association of hypertension with region and ur banization. Results-With age and urbanization kept constant, southern residence was ass ociated with hypertension among middle-aged non-Hispanic white men (odds ra tio [OR], 1.49; 95% confidence interval [CI], 1.12 to 1.90; P<0.006), non-H ispanic black men (OR, 1.36; 95% CI, 1.05 to 1.66; P=0.019), and non-Hispan ic black women (OR, 1.23, 95% CI, 1.01 to 1.45; P=0.034). Among older non-H ispanic white men, a significant interaction was noted between region and u rbanization (P=0.01), with a higher prevalence in the south only for nonmet ropolitan residents (OR, 1.32; 95% CI, 1.06 to 1.56; P<0.013). A similar bu t not statistically significant trend was also confirmed among non-Hispanic black men in logistic regression analysis (OR, 1.38; 95% CI, 0.97 to 1.68; P=0.061). No statistically significant association was observed for urbani zation or region in the other subgroups. Conclusions-Southern residence was associated with increased hypertension p revalence among middle-aged non Hispanic white men, non-Hispanic black men and women, and older non-Hispanic white men.