Lung clearance index at 4 years predicts subsequent lung function in children with cystic fibrosis.

Rationale: The markedly improved life expectancy of children with cystic fibrosis (CF) has created a new challenge, as traditional markers of lung disease are frequently normal in young children. This prevents identification of individuals who may benefit from more aggressive therapy and also obliges large study numbers and prolonged duration for intervention studies. There is an urgent need for alternative surrogates that detect early lung disease and track through early childhood.Objectives: This study aimed to determine whether multiple-breath washout (MBW) results at preschool age can predict subsequent abnormal lung function.Methods: Preschool children (3–5 yr) with CF and healthy control subjects underwent spirometry and MBW with testing repeated during early school age (6–10 yr). Primary outcomes were FEV1 from spirometry and lung clearance index (LCI) from MBW.Measurements and Main Results: Forty-eight children with CF and 45 healthy children completed testing. Thirty-five (73%) children with CF h...