The inspiratory capacity/total lung capacity ratio as a predictor of survival in an emphysematous phenotype of chronic obstructive pulmonary disease
Authors French A, Balfe D, Mirocha J, Falk J, Mosenifar Z
Received 31 October 2014
Accepted for publication 10 January 2015
Published 13 July 2015 Volume 2015:10(1) Pages 1305—1312
Checked for plagiarism Yes
Review by Single anonymous peer review
Peer reviewer comments 3
Editor who approved publication: Dr Richard Russell
Aimee French, David Balfe, James M Mirocha, Jeremy A Falk, Zab Mosenifar
Cedars-Sinai Medical Center, Division of Pulmonary and Critical Care Medicine, Los Angeles, CA, USA
Background: Forced expiratory volume in 1 second (FEV1) grades severity of COPD and predicts survival. We hypothesize that the inspiratory capacity/total lung capacity (IC/TLC) ratio, a sensitive measure of static lung hyperinflation, may have a significant association with survival in an emphysematous phenotype of COPD.
Objectives: To access the association between IC/TLC and survival in an emphysematous phenotype of COPD.
Methods: We performed a retrospective analysis of a large pulmonary function (PF) database with 39,050 entries, from April 1978 to October 2009. Emphysematous COPD was defined as reduced FEV1/forced vital capacity (FVC), increased TLC, and reduced diffusing capacity of the lungs for carbon monoxide (DLCO; beyond 95% confidence intervals [CIs]). We evaluated the association between survival in emphysematous COPD patients and the IC/TLC ratio evaluated both as dichotomous (≤25% vs >25%) and continuous predictors. Five hundred and ninety-six patients had reported death dates.
Results: Univariate analysis revealed that IC/TLC ≤25% was a significant predictor of death (hazard ratio [HR]: 2.39, P<0.0001). Median survivals were respectively 4.3 (95% CI: 3.8–4.9) and 11.9 years (95% CI: 10.3–13.2). Multivariable analysis revealed age (HR: 1.19, 95% CI: 1.14–1.24), female sex (HR: 0.69, 95% CI: 0.60–0.83), and IC/TLC ≤25% (HR: 1.69, 95% CI: 1.34–2.13) were related to the risk of death. Univariate analysis showed that continuous IC/TLC was associated with death, with an HR of 1.66 (95% CI: 1.52–1.81) for a 10% decrease in IC/TLC.
Conclusion: Adjusting for age and sex, IC/TLC ≤25% is related to increased risk of death, and IC/TLC as a continuum, is a significant predictor of mortality in emphysematous COPD patients.
Keywords: emphysema, pulmonary function testing, mortality
This work is published and licensed by Dove Medical Press Limited. The full terms of this license are available at https://www.dovepress.com/terms.php and incorporate the Creative Commons Attribution - Non Commercial (unported, v3.0) License. By accessing the work you hereby accept the Terms. Non-commercial uses of the work are permitted without any further permission from Dove Medical Press Limited, provided the work is properly attributed. For permission for commercial use of this work, please see paragraphs 4.2 and 5 of our Terms.Download Article [PDF] View Full Text [HTML][Machine readable]