Reply to Chan: Identification of alpha-1 antitrypsin-deficient subjects with normal spirometry who may benefit from alpha-1 antitrypsin replacement

We thank Dr. Chan for his insightful comments and expert analysis of our paper, which raise a number of important questions.In our cohort of 52 individuals with a bronchodilator response (BDR), 40 individuals had follow-up spirometry. There was a mean (6SD) of 7.9 (69.1) subsequent pulmonary function tests performed per person and a mean of 3.4 (62.7) further BDRs performed per person. We repeated the linear mixed model that was used to estimate yearly FEV1 change and included the BDR at baseline as a covariate. BDR was not significantly associated with yearly FEV1 change (22.7 ml/yr; 95% confidence interval:225.2, 19.8;P= 0.82)