Relationship of emphysema and airway disease assessed by CT to exercise capacity in COPD

Alejandro A. Diaz, Brian Bartholmai, Raúl San José Estépar, James Ross, Shin Matsuoka, Tsuneo Yamashiro, Hiroto Hatabu, John J. Reilly, Edwin K. Silverman, George R. Washko

Research output: Contribution to journalArticle

43 Scopus citations

Abstract

Objective: To assess the association of emphysema and airway disease assessed by volumetric computed tomography (CT) with exercise capacity in subjects with chronic obstructive pulmonary disease (COPD). Methods: We studied 93 subjects with COPD (Forced Expiratory Volume in 1 s [FEV1] %predicted mean ± SD 57.1 ± 24.3%, female gender = 40) enrolled in the Lung Tissue Research Consortium. Emphysema was defined as percentage of low attenuation areas less than a threshold of -950 Hounsfield units (%LAA-950) on CT scan. The wall area percentage (WA%) of the 3rd to 6th generations of the apical bronchus of right upper lobe (RB1) were analyzed. The 6-min walk distance (6MWD) test was used as a measure of exercise capacity. Results: The 6MWD was inversely associated with %LAA-950 (r = -0.53, p < 0.0001) and with the WA% of 6th generation of RB1 only (r = -0.28, p = 0.009). In a multivariate regression model including CT indices of emphysema and airway disease that were adjusted for demographic and physiologic variables as well as brand of CT scanner, only the %LAA-950 remained significantly associated with exercise performance. Holding other covariates fixed, this model showed that a 10% increase of CT emphysema reduced the distance walked in 6 min 28.6 m (95% Confidence Interval = -51.2, -6.0, p = 0.01). Conclusion: These results suggest that the extent of emphysema but not airway disease measured by volumetric CT contributes independently to exercise limitation in subjects with COPD.

Original languageEnglish (US)
Pages (from-to)1145-1151
Number of pages7
JournalRespiratory Medicine
Volume104
Issue number8
DOIs
StatePublished - Aug 2010

ASJC Scopus subject areas

  • Pulmonary and Respiratory Medicine

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    Diaz, A. A., Bartholmai, B., San José Estépar, R., Ross, J., Matsuoka, S., Yamashiro, T., Hatabu, H., Reilly, J. J., Silverman, E. K., & Washko, G. R. (2010). Relationship of emphysema and airway disease assessed by CT to exercise capacity in COPD. Respiratory Medicine, 104(8), 1145-1151. https://doi.org/10.1016/j.rmed.2010.02.023