Abnormal preschool Lung Clearance Index (LCI) reflects clinical status and predicts lower spirometry later in childhood in cystic fibrosis

Background: Clinical and prognostic value of preschool Multiple Breath Washout (MBW) remains unclear. Methods: Initial MBW results (Exhalyzer (R) D, EcoMedics AG) in preschool Cystic Fibrosis (CF) subjects (age 2-6 years) at a time of clinical stability were compared to (1) concurrent clinical status measures and (2) later spirometry outcomes. Abnormal Lung Clearance Index (LCI) was defined using published reference data (ULN for LCI 8.0). Results: LCI was abnormal in 56% (28/50), with mean (SD) LCI 8.61(1.85) at age 4.71(1.3) years. Abnormal LCI was associated with higher dornase alfa use, previous positive bacterial cultures and pF508.del homozygous genotype. Later spirometry (n = 44; mean (SD) 2.3(0.5) years after MBW) demonstrated that abnormal initial preschool LCI was a strong predictor of lower later spirometry outcomes. Conclusion: Abnormal preschool LCI was associated with concurrent measures of clinical status and later spirometry deficits, suggesting early prognostic utility of MBW testing in this age range. (C) 2019 European Cystic Fibrosis Society. Published by Elsevier B.V. All rights reserved.