Lung function is abnormal in 3-month-old infants with cystic fibrosis diagnosed by newborn screening

Abstract

Background Long-term benefits of newborn screening (NBS) for cystic fibrosis (CF) have been established with respect to nutritional status, but effects on pulmonary health remain unclear. Hypothesis With early diagnosis and commencement of standardised treatment, lung function at ∼3 months of age is normal in NBS infants with CF. Methods Lung clearance index (LCI) and functional residual capacity (FRC) using multiple breath washout (MBW), plethysmographic (pleth) FRC and forced expirations from raised lung volumes were measured in 71 infants with CF (participants in the London CF Collaboration) and 54 contemporaneous healthy controls age ∼3 months. Results Compared with controls, and after adjustment for body size and age, LCI, FRC_MBW and FRC_pleth were significantly higher in infants with CF (mean difference (95% CI): 0.5 (0.1 to 0.9), p=0.02; 0.4 (0.1 to 0.7), p=0.02 and 0.9 (0.4 to 1.3), p0.5) and flows (FEF_25–75) were significantly lower (−0.9 (−1.3 to −0.6), p1.96 z-scores) and 25% (17/68) an abnormally low FEV_0.5 (below −1.96 z-scores). While only eight infants with CF had abnormalities of LCI and FEV_0.5, using both techniques identified abnormalities in 35% (24/68). Hyperinflation (FRC_pleth >1.96 z-scores) was identified in 18% (10/56) of infants with CF and was significantly correlated with diminished FEF_25–75 (r=−0.43, p0.5. Conclusion Despite early diagnosis of CF by NBS and protocol-driven treatment in specialist centres, abnormal lung function, with increased ventilation inhomogeneity and hyperinflation and diminished airway function, is evident in many infants with CF diagnosed through NBS by 3 months of age.