Course of lung function in children with cystic fibrosis in their first 3 years of life

Introduction. The early prevention of respiratory complications in children with cystic fibrosis is determining for a longer survival. The implementation of lung function tests in the first months of life allows to detect respiratory involvement, even in asymptomatic children. Objective. To assess the course of lung function in children with cystic fibrosis in their first 3 years of life and identify the factors affecting it. Population and methods. Observational, retrospective, analytical study. Children younger than 36 months with at least 2 lung function tests were included. Results. Between 2008 and 2016, 48 patients were included; 85 % of them had been diagnosed by newborn screening. The first lung function test was done at 5 months old. The median Z-score of maximal flow at functional residual capacity was -0.05 (interquartile range: -1.09 to 1.08). The median change in the maximal flow Z-score between tests was -0.32 (interquartile range: -1.11 to 0.25), p = 0.045. Patients with Staphylococcus aureus respiratory infections, especially methicillin-resistant SA, evidenced a greater deterioration of lung function compared to those without infection. Neither sex nor the type of genetic mutation were associated with the course of lung function. Nutritional recovery throughout the study was really good. Conclusion. Lung function in children with cystic fibrosis worsens progressively during their first 3 years of life. These findings are associated with Staphylococcus aureus respiratory infections.