Sex-race differences in the relationship between obesity and asthma: the behavioral risk factor surveillance system,...

Although prospective data are limited, recent cross-sectional studies support obesity as a cause of asthma. They also suggest that the association is present only among women. Our analysis examines possible sex-race differences in the relationship between obesity and asthma.

We examined data from the 2000 Behavioral Risk Factor Surveillance System. To minimize diagnostic bias, the sample was limited to adults aged 18 to 34 years. All cases had doctor-diagnosis of asthma and ongoing symptoms. Multiple logistic regression was used to examine risk factors for current asthma vs. never having asthma.

Obesity and asthma were more strongly related among women than men (test for interaction, p<0.01). Across increasing categories of body mass index (BMI), we observed a dose-response relationship among women (odds ratios: 0.9, 1.0 [reference], 1.0, 1.3, 1.5, 1.8, and 3.2) but only a non-significant increased risk in severely obese men (odd ratio: 2.0). In subgroup analyses, however, the obesity-asthma association was present in four of six sex-race/ethnicity subgroups, including black and Hispanic men.

Although the obesity-asthma association is stronger among women than men, our analysis demonstrates a strong positive association among men from minority groups. These race-specific results may help explain some of the "inconsistencies" in prior studies.