Lung Clearance Index and Structural Lung Disease on Computed Tomography in Early Cystic Fibrosis

Am J Respir Crit Care Med. 2016 Jan 1;193(1):60-7. doi: 10.1164/rccm.201507-1409OC.


Rationale: The lung clearance index is a measure of ventilation distribution derived from the multiple-breath washout technique. It has been suggested as a surrogate for chest computed tomography to detect structural lung abnormalities in individuals with cystic fibrosis (CF); however, the associations between lung clearance index and early structural lung disease are unclear.

Objectives: We assessed the ability of the lung clearance index to reflect structural lung disease on the basis of chest computed tomography across the entire pediatric age range.

Methods: Lung clearance index was assessed in 42 infants (ages 0-2 yr), 39 preschool children (ages 3-6 yr), and 38 school-age children (7-16 yr) with CF before chest computed tomography and in 72 healthy control subjects. Scans were evaluated for CF-related structural lung disease using the Perth-Rotterdam Annotated Grid Morphometric Analysis for Cystic Fibrosis quantitative outcome measure.

Measurements and main results: In infants with CF, lung clearance index is insensitive to structural disease (κ = -0.03 [95% confidence interval, -0.05 to 0.16]). In preschool children with CF, lung clearance index correlates with total disease extent. In school-age children, lung clearance index correlates with extent of total disease, bronchiectasis, and air trapping. In preschool and school-age children, lung clearance index has a good positive predictive value (83-86%) but a poor negative predictive value (50-55%) to detect the presence of bronchiectasis.

Conclusions: These data suggest that lung clearance index may be a useful surveillance tool to monitor structural lung disease in preschool and school-age children with CF. However, lung clearance index cannot replace chest computed tomography to screen for bronchiectasis in this population.

Keywords: child; cystic fibrosis; imaging; infant; multiple-breath washout.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Age Factors
  • Bronchiectasis / diagnosis
  • Bronchiectasis / physiopathology
  • Case-Control Studies
  • Child
  • Child, Preschool
  • Cystic Fibrosis / diagnostic imaging*
  • Cystic Fibrosis / physiopathology
  • Female
  • Humans
  • Infant
  • Lung / diagnostic imaging
  • Lung / physiology
  • Lung / physiopathology*
  • Lung Diseases / diagnosis
  • Lung Diseases / physiopathology
  • Male
  • Mucociliary Clearance / physiology
  • Severity of Illness Index
  • Tomography, X-Ray Computed