Purpose of review: Lung disease begins early in life in cystic fibrosis (CF), yet our understanding of CF lung abnormalities in the first years of life remains limited. By facilitating earlier diagnosis, newborn screening for CF provides the opportunity to understand and characterize presymptomatic lung disease in infants and young children. This could lead to earlier interventions to mitigate disease progression at a time when therapeutic intervention or prevention may be most effective. This article reviews lung function tests that can be used during the first 5 years of life and discusses their potential applications as objective outcomes for clinical monitoring or research.
Recent findings: During the past decade, commercial equipment for assessing a wide range of lung function tests in infants and preschool children has become available together with international guidelines and improved reference equations with which to interpret results. The lung clearance index, derived from multiple breath washout, has been shown to be far more sensitive to early CF lung disease than conventional spirometric assessments.
Summary: Although limited evidence exists as to whether incorporating lung function tests into routine clinical care can improve patient outcomes during the early years, this is likely to be helpful in preschool children if more sensitive tests such as the multiple breath washout become more widely available. There is an urgent need to assess which infant and preschool lung function outcomes will provide the most robust outcome measures in collaborative multicenter studies, so that they can be incorporated into early therapeutic intervention studies.