Rapid lung function decline in adults with early-stage cystic fibrosis lung disease

Rationale The prevalence of adults living with cystic fibrosis (CF) who have early-stage lung disease is increasing. Objectives Describe the prevalence and evaluate spirometric risk factors associated with the subgroup of patients with early-stage lung disease and FEV1 decline of ≥5% predicted/year. Methods Retrospective cohort study of patients ≥18 years with FEV1% predicted ≥80% included in the US CF Foundation Patient Registry from 2010–2013. Regression models were developed to estimate FEV1 rate of decline. Multivariable logistic analysis was used to assess if spirometric risk factors were associated with FEV1 decline. Measurements and main results 3,029 subjects were in the study cohort. Approximately 15% of the cohort had a substantial decline in lung function ≥5% predicted/year. In multivariable models adjusted for confounders, FEV1/FVC ratio <0.8 (Odds Ratio (OR) 1.63, 95% confidence interval (CI) 1.31 to 2.02) and history of FEV1% predicted variability (OR 2.35,95%CI 1.74 to 3.18) were associated with rapid lung function decline. Conclusions Even among adults with early-stage lung disease, approximately 15% are shown to progress and experience a large decline in lung function. This reinforces the concept that lung function in early-stage CF is not normal or mild. Rather, lung function decline may be delayed, but not avoided, in these individuals. Variability in FEV1% predicted and airway obstruction as measured by FEV1/FVC ratio may identify individuals at increased risk of decline. Adults with early-stage lung disease should be followed in clinic to monitor for onset of decline.