Body Mass Index and Hypertension Hemodynamic Subtypes in the Adult US Population

Background: Obesity produces various hemodynamic abnormalities that may impact hypertension subtypes. Similarly, the study of hypertension subtypes provides important information regarding the relative importance of hemodynamic abnormalities contributing to obesity-related hypertension. Methods: Cross-sectional analysis of adults enrolled in the Third National Health and Nutrition Examination Survey (NHANES III) (n= 16 545) and NHANES 1999-2004 (n= 12 137). We examined the relationship between body mass index (BMI) (calculated as weight in kilograms divided by height in meters squared) and the risk of hypertension and hemodynamic subtypes: isolated systolic hypertension (ISH), isolated diastolic hypertension (IDH), and systodiastolic hypertension (SDH). Results: In NHANES 1999-2004, the odds ratio (OR) for hypertension for every 5-unit increase in BMI was 1.45 (95% confidence interval [CI], 1.39-1.52) (P <.001). However, the magnitude of the relative increase in the odds of hypertension was higher among younger adults. Among patients with hypertension, increasing BMI was a significant predictor of IDH or SDH (OR for IDH or SDH, 1.04; 95% CI, 1.02-1.06) (P <.001), as opposed to ISH. Isolated systolic hypertension represented a minority of hypertension cases in obese men (38.9%; 95% CI, 30.9-47.6) but remained the most prevalent type in obese women (62.1%; 95% CI, 52.4%-71.0%) (P <.001), despite a significant relative decrease in the frequency of ISH with increasing BMI in both sexes. Findings in NHANES III were very similar. Conclusions: Isolated diastolic hypertension and SDH account for most cases of obesity-related hypertension, suggesting that determinants of mean arterial pressure account for the major burden of obesity-related hypertension in US adult men. These findings should be considered in the design of clinical trials and therapeutic strategies for obesity-related hypertension. Further studies should assess determinants of mean arterial pressure in obesity and the role of sex in the pathogenesis of obesity-related hypertension.