Computed tomography structural lung changes in discordant airflow limitation

PLoS One. 2013 Jun 13;8(6):e65177. doi: 10.1371/journal.pone.0065177. Print 2013.

Abstract

Background: There is increasing evidence that structural lung changes may be present before the occurrence of airflow limitation as assessed by spirometry. This study investigated the prevalence of computed tomography (CT) quantified emphysema, airway wall thickening and gas trapping according to classification of airflow limitation (FEV1/FVC <70% and/or < the lower limit of normal (LLN)) in (heavy) smokers.

Methods: A total number of 1,140 male former and current smokers participating in a lung cancer screenings trial (NELSON) were included and underwent chest CT scanning and spirometry. Emphysema was quantified by the 15(th) percentile, air way wall thickening by the square root of wall area for a theoretical airway with 10mm lumen perimeter (Pi10) and gas trapping by the mean lung density expiratory/inspiratory (E/I)-ratio. Participants were classified by entry FEV1/FVC: group 1>70%; group 2<70% but >LLN; and group 3<LLN. 32 restricted subjects, i.e. FEV1/FVC >70% but FEV1 <80% predicted, were excluded. Multivariate regression analysis correcting for covariates was used to asses the extent of emphysema, airway wall thickening and gas trapping according to three groups of airflow limitation.

Results: Mean (standard deviation) age was 62.5 (5.2) years and packyears smoked was 41.0 (18.0). Group 2 subjects when compared to group 1 had a significantly lower 15(th) percentile, -920.6 HU versus -912.2 HU; a higher Pi10, 2.87 mm versus 2.57 mm; and a higher E/I-ratio, 88.6% versus 85.6% (all p<0.001).

Conclusion: Subjects with an FEV1/FVC<70%, but above the LLN, have a significant greater degree of structural lung changes on CT compared to subjects without airflow limitation.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aged
  • Airway Obstruction / diagnostic imaging*
  • Airway Obstruction / pathology*
  • Airway Obstruction / physiopathology
  • Humans
  • Lung / diagnostic imaging*
  • Lung / pathology*
  • Lung / physiopathology
  • Male
  • Middle Aged
  • Pulmonary Disease, Chronic Obstructive / diagnostic imaging
  • Pulmonary Disease, Chronic Obstructive / pathology
  • Pulmonary Disease, Chronic Obstructive / physiopathology
  • Respiratory Function Tests
  • Smoking
  • Tomography, X-Ray Computed*

Grant support

Funding was provided by European Union (EU) Framework Package Seven (FP7), grant number 201379, COPACETIC. 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); and 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.