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Lung clearance index to monitor treatment response in pulmonary exacerbations in preschool children with cystic fibrosis
  1. Jonathan H Rayment1,2,
  2. Sanja Stanojevic1,2,
  3. Stephanie D Davis3,
  4. George Retsch-Bogart4,
  5. Felix Ratjen1,2,5
  1. 1 Division of Respiratory Medicine, Hospital for Sick Children, Toronto, Ontario, Canada
  2. 2 Department of Paediatrics, University of Toronto, Toronto, Ontario, Canada
  3. 3 Section of Pediatric Pulmonology, Allergy and Sleep Medicine, Department of Pediatrics, Riley Hospital for Children, Indiana University School of Medicine, Indianapolis, Indiana, USA
  4. 4 Division of Pediatric Pulmonology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
  5. 5 Translational Medicine Program, SickKids Research Institute, Toronto, ON, Canada
  1. Correspondence to Dr Jonathan H Rayment, Division of Respiratory Medicine, British Columbia Children’s Hospital, 4480 Oak St, Vancouver, BC V6H 3N1, Canada; jonathan.rayment{at}


Background Antibiotic treatment for pulmonary symptoms in preschool children with cystic fibrosis (CF) varies among clinicians. The lung clearance index (LCI) is sensitive to early CF lung disease, but its utility to monitor pulmonary exacerbations in young children has not been assessed.

Objective We aim to (1) understand how LCI changes during lower respiratory tract symptoms relative to a recent clinically stable measurement, (2) determine whether LCI can identify antibiotic treatment response and (3) compare LCI changes to changes in spirometric indices.

Methods LCI and spirometry were measured at quarterly clinic visits over a 12-month period in preschool children with CF. Symptomatic visits were identified and classified as treated or untreated. Treatment response was estimated using propensity score matching methods.

Results 104 symptomatic visits were identified in 78 participants. LCI increased from baseline in both treated (mean relative change +23.8% (95% CI 16.2 to 31.4)) and untreated symptomatic visits (mean relative change +11.2% (95% CI 2.4 to 19.9)). A significant antibiotic treatment effect was observed when LCI was used as the outcome measure (average treatment effect −15.5% (95% CI −25.4 to −5.6)) but not for z-score FEV1.

Conclusion LCI significantly deteriorated with pulmonary symptoms relative to baseline and improved with antibiotic treatment. These data suggest that LCI may have a role in the routine clinical care of preschool children with CF.

  • multiple breath washout
  • cystic fibrosis
  • pulmonary exacerbation
  • pulmonary function test
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  • Contributors All authors conceived of the study. SDD, GR-B and FR supervised data collection at their respective sites. JHR and SS analysed the data. JHR drafted the manuscript. All authors reviewed, revised and approved the final manuscript.

  • Funding This study was funded by the National Heart, Lung, and Blood Institute R01HL116232-04. JHR’s fellowship was funded by Cystic Fibrosis Canada.

  • Competing interests None declared.

  • Ethics approval The study was approved by the Research Ethics Boards at the Hospital for Sick Children (REB # 1000036303), Riley Children’s Hospital (1401277863), and the Office of Human Research Ethics at University of North Carolina at Chapel Hill (13-1258).

  • Provenance and peer review Not commissioned; externally peer reviewed.

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