Published online: September 11, 2019
African Americans experience a disproportionate burden of asthma-related morbidity and mortality compared to Whites. African Americans have a greater proportion of uncontrolled asthma, a lower likelihood of response to treatment, and a higher annual risk of asthma exacerbations. While socioeconomic factors have been independently linked with increased exacerbation risk in other studies, they do not entirely account for the increased risk in Blacks.
In an article recently published in The Journal of Allergy & Clinical Immunology (JACI), Grossman, Ortega, and colleagues tested the hypothesis that self-reported Black race and African ancestry contribute to risk for asthma exacerbations. They analyzed data from 12 multi-ethnic NIH National Heart Lung Blood Institute-sponsored asthma clinical trial cohorts consisting of 1,840 subjects (24% Black) with mild to moderate asthma. These trials had longitudinal data on exacerbations requiring systemic glucocorticoid treatment over a median observation period of 126 to 379 days. All trials included data on self-reported race, and a subset of trials included genome-wide genetic data to estimate global percent African ancestry.
Risk factors associated with an increased asthma exacerbation rate common to both Blacks and Whites included a history of prior exacerbations and lower lung function. Race-specific risk factors in Blacks included a history of chronic sinusitis, allergic rhinitis, and acid reflux. In Whites, risk factors included BMI, sex, and methacholine bronchial hyperresponsiveness. Race was not associated with the risk of exacerbation in the combined multi-ethnic cohort, however, in the 161 Blacks with genetic data, higher African ancestry greater than the median (≥82%) associated with an increased exacerbation risk.
This study found that genetic variation from a common African ancestry, not self-identified race, was a risk factor for exacerbations in self-reported Blacks. These findings suggest that studies based on self-reported race alone are insufficient to improve our understanding of the genetic and environmental factors that track with ancestry to influence racial differences in asthma morbidity.
The Journal of Allergy and Clinical Immunology (JACI) is an official scientific journal of the AAAAI, and is the most-cited journal in the field of allergy and clinical immunology.