@article {470396,
	title = {Relationship of emphysema and airway disease assessed by CT to exercise capacity in COPD},
	journal = {Respir Med},
	volume = {104},
	number = {8},
	year = {2010},
	month = {2010 Aug},
	pages = {1145-51},
	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 [FEV(1)] \%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.},
	keywords = {Aged, Exercise Tolerance, Female, Forced Expiratory Volume, Humans, Male, Pulmonary Disease, Chronic Obstructive, Pulmonary Emphysema, Respiratory Function Tests, Severity of Illness Index, Tomography, X-Ray Computed, Walking},
	issn = {1532-3064},
	doi = {10.1016/j.rmed.2010.02.023},
	author = {Diaz, Alejandro A and Bartholmai, Brian and San Jos{\'e} Est{\'e}par, Ra{\'u}l and Ross, James and Matsuoka, Shin and Yamashiro, Tsuneo and Hatabu, Hiroto and Reilly, John J and Silverman, Edwin K and Washko, George R}
}