Systolic Blood Pressure and Adiposity: Examination by Race and Gender in a Nationally Representative Sample of Young Adults

It has been suggested that the association between anthropometric measures of adiposity (e.g., waist circumference (WC) and body mass index (BMI)) and high blood pressure vary by race.1 These anthropometric measures, however, only broadly capture more complex underlying patterns of body composition and adiposity (e.g., visceral vs. subcutaneous adipose tissue, upper body vs. abdominal fat), which also vary by sex and race.2 Despite their relative lack of specificity with respect to adiposity, techniques for assessing anthropometric measures such as BMI and WC are comparatively inexpensive and widely accessible. Thus, further elucidation of how these relatively simple measures are associated with disease remains important. The present study describes the association between WC and systolic blood pressure (SBP), with a focus on how these relations may vary by race and sex, using a large nationally representative sample of young adults in the United States. We focus on SBP in the present study because, although associations have been shown to vary by age,3 many studies have shown SBP to be more important than diastolic blood pressure (DBP) with respect to health risk,4–9 and also possibly more responsive than DBP to changes in modifiable risk factors such as exercise, diet, and weight loss.10 WC has been shown to add to the prediction of visceral fat beyond measurements of BMI.11,12 Visceral adipose tissue is an independent predictor of the metabolic syndrome in both men and women,13 and has also been found to add to the prediction of hypertension.14,15 Following Tybor et al.,16 we use statistical partialling to remove the effect of BMI from the association between WC and SBP. WC partialled for BMI reflects WC independent of overall body size, and thus, by definition, must reflect body shape or body fat distribution. We also allow for the possibility that these associations may be nonlinear. Examination of these questions in this manner may provide more precise information about the pathophysiology underlying high blood pressure and also further guide risk stratification in clinical practice.