fumigatus Is Not a Bystander Phenomenon in Cystic Fibrosis Lung Disease To the Editor:

We have read with great interest the article by Baxter et al 1 in CHEST (May 2013) highlighting the importance of sensitization to Aspergillus fumigatus (Af) in progression of cystic fi brosis (CF) lung disease. We and many others have previously reported that sensitization to Af is frequent in patients with CF: It was observed in 31 % of the patient cohort (n 5 153) who were followed up at the Leuven CF referral center. 2 We also confi rmed signifi-cantly impaired lung function parameters in Af-sensitized compared with Af-nonsensitized patients, with an average diff erence in FEV 1 of 19 4 % predicted. In a multivariate analysis with age, sex, BMI, Pseudomonas aeruginosa colonization, pancreatic insuffi ciency, and gastroesophageal refl ux disease as covariates, a signifi-cantly lower FEV 1 and vital capacity ( P ,.001) wa