Biomarkers that can predict loss of asthma control among patients being considered for step-down therapy in well-controlled disease are lacking.
To evaluate if baseline biomarkers of type 2 airway inflammation and/or serial measurement of fractional exhaled nitric oxide (FeNO) predict loss of asthma control as therapy is stepped down.
In sub-analyses of a multi-center randomized, double-blind, parallel 3-arm trial comparing strategies for step-down therapy in well-controlled asthma (LASST), we assessed whether baseline atopy as determined by serum aeroallergen allergy screening test (Phadiatop), baseline serum eosinophil peroxidase (EpX), or baseline or serial FeNO measurements during follow-up, predicted the time to loss of asthma control among participants. Loss of asthma control was defined in the study protocol. We analyzed these associations in adjusted models including all participants, after testing for interactions with assignment to each of the three treatment groups (continuation of stable dose of combination ICS-LABA, step-down of inhaled corticosteroid (ICS), or discontinuation of long acting bronchodilator (LABA)).
Four hundred and forty-seven of the 553 LASST participants who were randomized to one of 3 treatment arms and had at least one biomarker measurement were included in this analysis. At baseline, higher levels of FeNO were significantly associated with greater levels of multi-allergen IgE levels (P<0.001), but not with serum EpX (p=0.742). Among all participants as a group, elevations in baseline biomarkers were not predictive of higher risk of treatment failure. In addition, FeNO levels measured serially at 6-week intervals, demonstrated that compared to participants with low levels (50 ppb) levels did not have significantly increased likelihood of subsequent treatment failure (hazard ratios (95% confidence interval) 1.03 (0.59, 1.78) and 1.29 (0.65, 2.54), respectively. There were no significant interactions of treatment group and baseline biomarkers.
In patients with well-controlled asthma, neither baseline levels of type 2 airway inflammatory biomarkers nor serial measures of FeNO are strong predictors of treatment failure.

Copyright © 2020. Published by Elsevier Inc.