Association of general and central obesity and atopic and nonatopic asthma in US adults.

OBJECTIVE: To examine the association of body mass index (BMI), waist circumference (WC), and waist-to-height ratio (WHtR) with the prevalence of asthma by atopic status and sex using nationally representative data in the US.

METHODS: The National Health and Nutrition Examination Survey 2005-2006 data were analyzed using areas under the receiver operating characteristic (ROC) curves (AUCs) and multivariate logistic regression models.

RESULTS: Women had higher AUCs (0.59-0.64) than men (0.50-0.58) across anthropometric indices and asthma outcomes. After controlling for sociodemographic characteristics and smoking status, only WHtR was positively associated with atopic asthma in both sexes (odds ratio per 1 SD [95% confidence interval]: men, 1.018 [1.004, 1.032], p = .01; women, 1.018 [1.006, 1.030], p = .003), and the associations persisted after further adjustment of BMI. Only in women was nonatopic asthma significantly associated with every 1 SD increase of BMI (odds ratio [95% confidence interval]: 1.018 [1.006, 1.030], p = .003), WC (1.018 [1.006, 1.030], p = .004), and WHtR (1.016 [1.004, 1.028], p = .008).

CONCLUSIONS: Using US national data, this study adds to the emerging evidence suggesting two possible distinct phenotypes: (1) obese men and women with atopic asthma and (2) obese women with nonatopic asthma. The mechanistic and therapeutic implications of these findings warrant further investigation.