Background: Biologic factors are known to contribute to asthma severity. It is unknown whether these factors differentially contribute to asthma severity in black compared with white subjects.Objective: We sought to assess the extent to which racial disparities between black and white subjects with severe asthma are attributable to physiologic, immunoinflammatory, and sociodemographic variables.Methods: Black and white asthmatic adults enrolled in a cross-sectional study focused on severe asthma were evaluated. Severe asthma was identified by using the American Thoracic Society definition. After initial univariable analyses, unconditional logistic regression models were used to estimate the probability of having severe asthma for black and white subjects.Results: Differences in severe asthma in black compared with white subjects were observed. In univariable analysis IgE level was not associated with severe asthma in black or white subjects, whereas in multivariable analysis IgE level was significantly associated with severe asthma for black subjects (P = .014) but not for white subjects. The odds of having severe asthma more than doubled for black subjects with 2 or more family members with asthma (P = .026), whereas the odds of severe asthma for white participants with a strong family history of asthma decreased by almost half (P = .05). Atopy was negatively associated with severe asthma in both races in univariable analysis but remained significant only in black subjects, whereas comorbidities were associated with severe asthma in white subjects.Conclusion: Biologic factors were distinctly associated with severe asthma only in black subjects. Studies that incorporate comprehensive evaluation of biologic factors associated with asthma might lead to the development of therapies that target biologic abnormalities in black subjects.

Background: Obesity has been proposed to be a risk factor for the development of childhood asthma.Objective: We sought to examine weight status from birth to age 5 years in relation to the occurrence of asthma at ages 6 and 8 years.Methods: Two hundred eighty-five full-term high-risk newborns with at least 1 asthmatic/atopic parent enrolled in the Childhood Origin of Asthma project were studied from birth to age 8 years. Overweight was defined by weight-for-length percentiles of greater than the 85th percentile before the age of 2 years and a body mass index percentile of greater than the 85th percentile at ages 2 to 5 years.Results: No significant concurrent association was found between overweight status and wheezing/asthma occurrence at each year of age. In contrast, longitudinal analyses revealed complex relationships between being overweight and asthma. Being overweight at age 1 year was associated with a decreased risk of asthma at age 6 (odds ratio [OR], 0.32; P = .02) and 8 (OR, 0.35; P = .04) years, as well as better lung function. However, being overweight beyond infancy was not associated with asthma occurrence. In fact, only children who were overweight at age 5 years but not at age 1 year had an increased risk of asthma at age 6 years (OR, 5.78; P = .05).Conclusion: In children genetically at high risk of asthma, being overweight at age 1 year was associated with a decreased risk of asthma and better lung function at ages 6 and 8 years. However, being overweight beyond infancy did not have any protective effect and even could confer a higher risk for asthma.