Asthma: race-related differences in eosinophilic airway inflammation

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Takeaway
  • There are race-related differences in eosinophilic airway inflammation among asthmatic patients receiving inhaled corticosteroids (ICS).

Why this matters

  • Increased risk of eosinophilic inflammation in ICS-treated (ICS+) African-Americans may reflect corticosteroid insensitivity.

Key results

  • 17% of ICS+ participants had eosinophilic airway inflammation, with no significant differences between African-Americans and Caucasians. 
  • African-Americans with eosinophilic inflammation were twice as likely to have mixed granulocytic pattern (7% vs 3%; P=.02) and less likely to exhibit neutrophilic inflammation (71% vs 75%; P=.02). 
  • 36% of subjects not treated with ICS (ICS-) had eosinophilic inflammation, with no significant difference between African-Americans and Caucasians (39% vs 35%; P=.65). 
  • ICS- African-Americans with eosinophilic inflammation were 4 times as likely to have mixed granulocytic inflammation (14% vs 3%; P=.003). 
  • African-American subjects with noneosinophilic inflammation were twice as likely to exhibit neutrophilic inflammation (35% vs 17%; P=.004). 
  • On multivariable analysis, race was associated with eosinophilic inflammation in ICS+ subjects only (OR 1.58; 95% CI 1.01-2.48; P=.046).

Study design

  • Secondary analysis of data from 10 clinical trials conducted by the Asthma Clinical Research Network and AsthmaNet. 
  • Funding: Asthma Clinical Research Network and AsthmaNet sponsored by National Heart, Lung, and Blood Institute.

Limitations

  • Clinical trial setting. 
  • Self-reported race. 
  • 2 inflammation phenotypes only.