Infant Lung Function in Cystic Fibrosis: A Real-World Study

Previous research showed that lung function abnormalities are common in infants with cystic fibrosis (IwCF) but real-world data are missing.

This single-center retrospective study analyzed infant lung function results from IwCF born in 2012-2018. The tests were conducted at Great Ormond Street Hospital, London, as part of routine care at 3 months, 1 year, and 2 years of age. Z-scores for SF₆ Lung Clearance Index (zLCI), plethysmographic FRC (zFRC_pleth) and FEV_0.5 were derived. Microbiology and antibiotics prescription from 3 months before lung function assessments, up to the closest medical review following the lung function encounter, were analyzed, along with changes in management advised by the physician.

A total of 126 lung function encounters (n = 43 at 3 months, 46 at 1 year, 37 at 2 years) from 60 IwCF were included. LCI was abnormal (zLCI > 1.96) in 31% (12/39) of 3-month-olds (mean± zLCI 1.21 ± 1.08), 28% (12/43) of 1-year-olds and 19% (7/36) of 2-year-olds (mean± zLCI 1.13 ± 1.10). Among 74 cases with recent positive microbiology or abnormal chest findings at medical review, 100% (31/31) of those with abnormal lung function and 86% (37/43) of those with normal lung function (p = 0.04) had a recent antibiotic prescription or a change in clinical management. Conversely, in encounters with abnormal lung function but normal clinical findings, management changes occurred in only 12% (2/16) of cases.

In this real-word cohort of IwCF, clinical management was mainly influenced by clinical findings and only marginally by abnormal lung function (elevated FRC or LCI).