Assessing differences in inhaled corticosteroid response by self-reported race-ethnicity and genetic ancestry among individuals with asthma

Asthma is a huge problem in the United States, and particularly among African-Americans.  Prior work has shown that African ancestry is associated with more asthma exacerbations, night-time symptoms, and worse lung function. What is it that makes African Americans so susceptible to poorly controlled asthma?  This is a question that Wells and colleagues investigate in this month’s issue of the Journal of Allergy and Clinical Immunology (J Allergy Clin Immunol 2016; 137(5): 1364-1369).  In particular, they seek to answer if African-American ancestry is linked to a poorer response to inhaled corticosteroids (ICS), one of the first-line agents in treating persistent asthma.

To measure the response to ICS, 399 participants completed six weeks of observed ICS treatment.  242 of these were African American, compared to 97 who were European in origin.  Adherence was monitored by a special device (DOSER-CT) to make sure that participants were taking their medication; asthma response was measured by simple lung function tests, and ancestry was confirmed by genetic analysis.  After six weeks, there did not appear to be a relationship between change in lung function in response to ICS and African ancestry.

That’s not to say that African Americans don’t have particular genes that make them more or less likely to respond to inhaled corticosteroids. Rather, genetic effects are spread in such a way that, all other things held equal, there’s a similar response among African Americans and European Americans.  It’s good to know that, in tackling the epidemic of asthma in African-Americans, ICS are useful and effective.