University of Groningen Computed Tomography Structural Lung Changes in Discordant Airflow Limitation Hoesein, Firdaus A. A. Mohamed; de Jong, Pim A.; Lammers, Jan-Willem J.; Mali, Willem

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 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 percentile, 2920.6 HU versus 2912.2 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. Citation: Mohamed Hoesein FAA, de Jong PA, Lammers J-WJ, Mali WP, Schmidt M, et al. (2013) Computed Tomography Structural Lung Changes in Discordant Airflow Limitation. PLoS ONE 8(6): e65177. doi:10.1371/journal.pone. 0065177 Editor: Xiaoming Yang, University of Washington School of Medicine, United States of America Received January 30, 2013; Accepted April 24, 2013; Published June 13, 2013 Copyright: 2013 Mohamed Hoesein et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Funding: 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. Competing Interests: HK is member of the medical advisory board of Roche Diagnostics. Siemens Germany and Roche Diagnostics provided funding towards this study. There are no patents, products in development or marketed products to declare. This does not alter the authors’ adherence to all the PLOS ONE policies on sharing data and materials. * E-mail: fmohamedhoesein@gmail.com