Pulmonary function patterns and their association with genotype and phenotype in adult cystic fibrosis patients

Background: While cystic fibrosis (CF) lung disease is generally considered to be an obstructive disorder, other pulmonary function patterns (PFP) may occur. Furthermore, little is known about possible associations between PFP and genotype or phenotypical characteristics. Methods: Cross-sectional study including CF patients aged 16 years or more, identifying different PFP and exploring associations between PFP and genotype or phenotypical characteristics. Results: Obstructive PFP was most prevalent in our population (n = 80), comprising obstructive lung disease (62.5%), small airway (obstructive) disease (11.2%), and mixed obstructive-restrictive disorder (1.3%). However, one in four adult CF patients did not show any obstruction at all: normal (13.7%) or restrictive (8.8%) lung disease and isolated diffusion disorder (2.5%). Obstructive PFP was associated with a greater proportion of CF-related diabetes mellitus (CFRD) (P = 0.04), Pseudomonas aeruginosa colonization (P = 0.02) and frequent exacerbators (P = 0.04). We observed no association between PFP and genotype. Conclusions: Obstructive PFP remains the most common pulmonary function pattern in adult CF and is associated with CFRD, Pseudomonas aeruginosa colonization and frequent exacerbators.