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

Abstract

Background: In the United States, stroke mortality is higher in the south than in other regions. Hypertension is the main risk factor for stroke among older adults; however, few studies have examined group-specific regional and urbanization differences in hypertension prevalence.

Methods: Data from the Third National Health and Nutritional Examination Survey (NHANES III), 1988 to 1994, were analyzed to calculate the prevalence of hypertension (systolic >140 mm Hg and/or diastolic >90 mm Hg and/or taking 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 urbanization.

Results: With age and urbanization kept constant, southern residence was associated with hypertension among middle-aged non-Hispanic white men (odds ratio [OR], 1.49; 95% confidence interval [CI], 1.12 to 1.90; P<0.006), non-Hispanic black men (OR, 1.36; 95% CI, 1.05 to 1.66; P=0.019), and non-Hispanic black women (OR, 1.23; 95% CI, 1.01 to 1.45; P=0.034). Among older non-Hispanic white men, a significant interaction was noted between region and urbanization (P=0.01), with a higher prevalence in the south only for nonmetropolitan residents (OR, 1.32; 95% CI, 1.06 to 1.56; P<0.013). A similar but 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 urbanization or region in the other subgroups.

Conclusions: Southern residence was associated with increased hypertension prevalence among middle-aged non-Hispanic white men, non-Hispanic black men and women, and older non-Hispanic white men.