CT air trapping is independently associated with lung function reduction over time

PLoS One. 2013 Apr 16;8(4):e61783. doi: 10.1371/journal.pone.0061783. Print 2013.

Abstract

Purpose: We aimed to study the association between lung function decline and quantitative computed tomography (CT) air trapping.

Materials and methods: Current and former heavy smokers in a lung cancer screening trial underwent volumetric low-dose CT in inspiration and expiration. Spirometry was obtained at baseline and after 3 years. The expiratory to inspiratory ratio of mean lung density (E/I-ratioMLD) was used to quantify air trapping. CT emphysema was defined as voxels in inspiratory CT below -950 Hounsfield Unit. Linear mixed modeling was used to determine the association between CT air trapping and lung function.

Results: We included 985 subjects with a mean age of 61.3 years. Independent of CT emphysema, CT air trapping was significantly associated with a reduction in forced expiratory volume in one second (FEV1) and the ratio of FEV1 over the forced vital capacity (FEV1/FVC); FEV1 declines with 33 mL per percent increase in CT air trapping, while FEV1/FVC declines 0.58% per percent increase (both p<0.001). CT air trapping further elicits accelerated loss of FEV1/FVC (additional 0.24% reduction per percent increase; p = 0.014).

Conclusion: In a lung cancer screening cohort, quantitatively assessed air trapping on low-dose CT is independently associated with reduced lung function and accelerated decline of FEV1/FVC.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Female
  • Forced Expiratory Volume / physiology
  • Humans
  • Lung / physiopathology*
  • Male
  • Middle Aged
  • Respiratory Function Tests
  • Smoking / adverse effects
  • Spirometry
  • Tomography, X-Ray Computed / methods*
  • Vital Capacity / physiology

Grant support

The NELSON-trial was sponsored by: Netherlands Organisation for Health Research and Development (ZonMw); Dutch Cancer Society Koningin Wilhelmina Fonds (KWF); Stichting Centraal Fonds Reserves van Voormalig Vrijwillige Ziekenfondsverzekeringen (RvvZ); Siemens Germany; Roche Diagnostics; Rotterdam Oncologic Thoracic Steering committee (ROTS); G.Ph.Verhagen Trust, Flemish League Against Cancer, Foundation Against Cancer and Erasmus Trust Fund. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.