Bronchodilator Reversibility in the GAN Severe Asthma Cohort

Abstract

Background: Positive bronchodilator reversibility (BDR) is a diagnostic criterion for asthma. However, patients with asthma may exhibit a negative BDR response. Aim: To describe the frequency of positive and negative BDR response in patients with severe asthma and study associations with phenotypic characteristics. Methods: A positive BDR response was defined as an increase in FEV1 >200 mL and >12% upon testing with a short-acting ß-agonist. Results: BDR data were available for 793 of the 2013 patients included in the German Asthma Net (GAN) severe asthma registry. Of these, 250 (31.5%) had a positive BDR response and 543 (68.5%) a negative BDR response. Comorbidities significantly associated with a negative response were gastroesophageal reflux disease (GERD) (28.0% vs 40.0%, P <0.05). There were no differences in diffusion capacity of the lung for carbon monoxide, single breath (% pred, 70% vs 71%). Multivariate linear regression analysis identified an association between positive BDR response and lower baseline FEV1% (P