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 w3 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 w3 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), p¼0.02; 0.4 (0.1 to 0.7), p¼0.02 and 0.9 (0.4 to 1.3), p<0.001, z-scores, respectively), while forced expiratory volume (FEV 0.5 ) and flows (FEF 25e75 ) were significantly lower (À0.9 (À1.3 to À0.6), p<0.001 and À0.7 (À1.1 to À0.2), p¼0.004, z-scores, respectively). 21% (15/70) of infants with CF had an elevated LCI (>1.96 z-scores) and 25% (17/68) an abnormally low FEV 0.5 (below À1.96 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 25e75 (r¼À0.43, p<0.001) but not with LCI or FEV 0.5 . 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.

Background: Information regarding recruitment of infants to research studies following the diagnosis of cystic fibrosis (CF) via newborn screening (NBS) is not currently available. This study aimed to assess parental attitudes and the feasibility of recruiting and retaining both NBS infants with CF and healthy control infants to a longitudinal, observational study. Methods: All infants underwent pulmonary function tests (PFTs) at~3 and~12 months of age. Infants with CF had additional combined chest high resolution computed tomography (HRCT), bronchoscopy and broncho-alveolar lavage (BAL) at~12 months of age. Parental attitude questionnaires (PAQs) were administered to all parents following the~3 month PFTs and to parents of infants with CF after completion of all tests at~12 months. Results: 86% (92/107) of families whose infant had CF consented to participate, of whom 92% had PFTs at~3 months of age with 99% of these having PFTs at~12 months of age. Recruitment of healthy controls was feasible but more challenging; 29% of those contacted agreed to participate; 73% of these had PFTs at~3 months of age; of whom 83% had repeated PFTs at~12 months of age. Completed PAQs were received from 71% of parents, (both of CF and healthy infants) at~3 months and from 58% parents of infants with CF at~12 months. Responses from the PAQs were generally positive, 95% of parents indicated they would recommend participation in such studies to other families. Discrepancies between responses at 3 and 12 months suggested that parental understanding of what the research entailed developed during the course of the study. Conclusions: The high recruitment and retention rates for newly diagnosed CF NBS infants to this observational study are encouraging. These findings will help inform future study design both in the field of CF and other conditions diagnosed by NBS.