Responsiveness to parenteral corticosteroids and lung function trajectory in adults with moderate-to-severe asthma

Rationale: It is unclear why select patients with moderate-tosevere asthma continue to lose lung function despite therapy. We hypothesized that participants with the smallest responses to parenteral corticosteroids have the greatest risk of undergoing a severe decline in lung function. Objectives: To evaluate corticosteroid-response phenotypes as longitudinal predictors of lung decline. Methods: Adults within the NHLBI SARP III (Severe Asthma Research Program III) who had undergone a course of intramuscular triamcinolone at baseline and at >2 annual follow-up visits were evaluated. Longitudinal slopes were calculated for each participant's postbronchodilator FEV1% predicted. Categories of participant FEV1 slope were defined: Severe decline, .2% loss/yr; mild decline, .0.5-2.0% loss/yr; no change, 0.5% loss/yr to,1% gain/yr; and improvement,>1% gain/yr. Regression models were used to develop predictors of severe decline. Measurements and Main Results: Of 396 participants, 78 had severe decline, 91 had mild decline, 114 had no change, and 113 showed improvement. The triamcinolone-induced difference in the post-bronchodilator FEV1% predicted (derived by baseline subtraction) was related to the 4-year change in lung function or slope category in univariable models (P,0.001). For each 5% decrement in the triamcinolone-induced difference the FEV1% predicted, there was a 50% increase in the odds of being in the severe decline group (odds ratio, 1.5; 95% confidence interval, 1.3-1.8), when adjusted for baseline FEV1, exacerbation history, blood eosinophils and body mass index. Conclusions: Failure to improve the post-bronchodilator FEV1 after a challenge with parenteral corticosteroids is an evoked biomarker for patients at risk for a severe decline in lung function.