Clinical Characteristics Associated With Lung Function Decline in Individuals With Adult-Diagnosed Cystic Fibrosis Contemporary Analysis of the Canadian CF Registry

BACKGROUND: Individuals with cystic fibrosis (CF) diagnosed as adults represent a rare but growing subset of the CF population. Limited studies have described their lung function trajectories. RESEARCH QUESTION: What is the overall trajectory of lung function and clinical characteristics associated with lung function decline in people who receive a diagnosis of CF as adults? STUDY DESIGN AND METHODS: The Canadian CF Patient Registry (CCFR) was used to identify patients with CF who were >= 18 years of age at diagnosis and received a diagnosis between 2000 and 2017. Linear mixed-effects models were used to quantify the change in lung function over age and to examine clinical characteristics associated with lung function decline. RESULTS: Lung function was stable in early adulthood, with a decline in middle adulthood (age 30-50 years) and a greater decline after 50 years of age. Individuals who receive a diagnosis at older ages (> 50 years: slope, -0.71%/y; 41-50 years: -0.68%/y; 31-40 years: - 0.29%/y; 18-30 years: -0.28%/y) and those demonstrating pulmonary symptoms (slope, - 0.41%/y) compared with no pulmonary symptoms at baseline were associated with faster rate of lung function decline. INTERPRETATION: The lung function of who receive a diagnosis of CF as adults in the CCFR declines slowly compared with estimates from the overall adult CF population. Individuals with adult-diagnosed CF who are older and demonstrate pulmonary symptoms at diagnosis experience a faster rate of lung function decline and should be monitored more closely.