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

Abstract

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.

Keywords: Adult; Cohort studies; Cystic fibrosis; Respiratory function tests; Risk factors.