Quality of life is poorly correlated to lung disease severity in school-aged children with cystic fibrosis

Background: There is no data exclusively on the relationship between health-related quality-of-life (HRQOL) and lung disease severity in early school-aged children with cystic fibrosis (CF). Using data from the Australian Respiratory Early Surveillance Team for Cystic Fibrosis (AREST CF) we assessed the relationships between HRQOL, lung function and structure. Methods: 125 children aged 6.5-10 years enrolled in the AREST CF program were included from CF clinics at Royal Children's Hospital (RCH), Melbourne (n = 66) and Perth Children's Hospital (PCH), Perth (n = 59), Australia. Demographics, HRQOL measured by Cystic Fibrosis Questionnaire-Revised (CFQ-R), spirometry, multiple-breath washout (MBW) and chest CT were collected across two years. Correlation between CFQ-R scores and lung structure/function parameters and agreement between parent-proxy and child-reported HRQOL were evaluated. Results: No correlation was observed between most CFQ-R domain scores and FEV1 z-scores, excepting weak-positive correlation with parent CFQ-R Physical (rho = 0.21, CI 0.02-0.37), and Weight (rho = 0.21, CI 0.03-0.38) domain and child Body domain (rho = 0.26, CI 0.00-0.48). No correlation between most CFQ-R domain scores and LCI values was noted excepting weak-negative correlation with parent Respiratory (rho = -0.23, CI ⁻0.41-⁻0.05), Emotional (rho = -0.24, CI ⁻0.43-⁻0.04), and Physical (-0.21, CI ⁻0.39-⁻0.02) domains. Furthermore, structural lung disease on CT data demonstrated little to no association with CFQ-R parent and child domain scores. Additionally, no agreement between child self-report and parent-proxy CFQ-R scores was observed across the majority of domains and visits. Conclusion: HRQOL correlated poorly with lung function and structure in early school-aged children with CF, hence clinical trials should consider these outcomes independently when determining study end-points.