Introduction: The lung clearance index (LCI) is a measure of ventilation inhomogeneity from the multiple breath washout test (MBW). In older children with CF, LCI is reported to have good agreement with the presence of structural lung disease on chest computed tomography (CT). We assessed the agreement between LCI and bronchiectasis across the entire paediatric age range. Methods: LCI was assessed in 44 infants with CF (0-2y) using MBW with sulphur hexafluoride under sedation and 76 children with CF (3-16y) using multiple breath nitrogen washout prior to a volumetric inspiratory chest CT scan. Bronchiectasis presence and extent was assessed using a simplified CF-CT scoring system. ROC analysis was used to assess agreement. Results: There was significant agreement between LCI and the presence of bronchiectasis in preschool (3-6y; n = 29; ROC area under curve (AUC) = 0.78; p = 0.03), school-age (7-9y; n = 25; ROC AUC = 0.80; p = 0.01) and adolescence (10-16y; n = 22; ROC AUC = 0.84; p = 0.03) but not infancy (ROC AUC = 0.618; p = 0.24). In children with CF an LCI greater than 7.26 lung turnovers had an 88% sensitivity, 70% specificity, 86% positive predicted value (PV) and 73% negative PV to detect the presence of bronchiectasis on CT. LCI values correlated with the extent of bronchiectasis in children (p < 0.001) but not infants (p = 0.48). Conclusions: These data suggest LCI may be useful as a surveillance tool in children with CF but there is not enough evidence to suggest LCI should be used as a substitute for CT to detect structural lung disease. Longitudinal studies are required to assess how LCI tracks in early CF lung disease.
|Journal||European Respiratory Journal|
|Publication status||Published - 2014|