Impact of race on asthma treatment failures in the asthma clinical research network

Abstract

Rationale: Recent studies suggest that people with asthma of different racial backgrounds may respond differently to various therapies.

Objectives: To use data from well-characterized participants in prior Asthma Clinical Research Network (ACRN) trials to determine whether racial differences affected asthma treatment failures.

Methods: We analyzed baseline phenotypes and treatment failure rates (worsening asthma resulting in systemic corticosteroid use, hospitalization, emergency department visit, prolonged decrease in peak expiratory flow, increase in albuterol use, or safety concerns) in subjects participating in 10 ACRN trials (1993-2003). Self-declared race was reported in each trial and treatment failure rates were stratified by race.

Measurements and main results: A total of 1,200 unique subjects (whites = 795 [66%]; African Americans = 233 [19%]; others = 172 [14%]; mean age = 32) were included in the analyses. At baseline, African Americans had fewer asthma symptoms (P < 0.001) and less average daily rescue inhaler use (P = 0.007) than whites. There were no differences in baseline FEV(1) (% predicted); asthma quality of life; bronchial hyperreactivity; or exhaled nitric oxide concentrations. A total of 147 treatment failures were observed; a significantly higher proportion of African Americans (19.7%; n = 46) experienced a treatment failure compared with whites (12.7%; n = 101) (odds ratio = 1.7; 95% confidence interval, 1.2-2.5; P = 0.007). When stratified by treatment, African Americans receiving long-acting β-agonists were twice as likely as whites to experience a treatment failure (odds ratio = 2.1; 95% confidence interval, 1.3-3.6; P = 0.004), even when used with other controller therapies.

Conclusions: Despite having fewer asthma symptoms and less rescue β-agonist use, African-Americans with asthma have more treatment failures compared with whites, especially when taking long-acting β-agonists.

Figure 1.

Treatment failure Kaplan-Meier survival curves for whites (n = 795) and African Americans (n = 233) participating in all Asthma Clinical Research Network trials independent of treatment group assignment.

Figure 2.

Treatment failure Kaplan-Meier survival curves for whites (n = 578) and African Americans (n = 152) participating in Asthma Clinical Research Network trials who did not receive long-acting β-agonists.

Figure 3.

Treatment failure Kaplan-Meier survival curves for whites (n = 217) and African Americans (n = 81) participating in Asthma Clinical Research Network trials who received long-acting β-agonists.

Figure 4.

Treatment failure Kaplan-Meier survival curves for whites (n = 114) and African Americans (n = 43) participating in Asthma Clinical Research Network trials who received long-acting β-agonists and inhaled corticosteroids (ICS) concurrently.

Figure 5.

Treatment failure Kaplan-Meier survival curves for whites (n = 47) and African Americans (n = 29) participating in Asthma Clinical Research Network trials who received long-acting β-agonists and leukotriene modifiers concurrently.