COPD as a systemic disease: impact on physical functional limitations.
OBJECTIVE
Although chronic obstructive pulmonary disease (COPD) has a major impact on physical health, the specific impact of COPD on physical functional limitations has not been characterized clearly. We aimed to elucidate the physical functional limitations that are directly attributable to COPD compared to a matched referent group without the condition.


METHODS
We used the Function, Living, Outcomes, and Work (FLOW) cohort study of adults with COPD (n=1202) and referent subjects matched by age, sex, and race (n=302) to study the impact of COPD on the risk of a broad array of functional limitations using validated measures: lower extremity function (Short Physical Performance Battery [SPPB]), submaximal exercise performance (Six Minute Walk Test [SMWT]), standing balance (Functional Reach Test), skeletal muscle strength (manual muscle testing with dynamometry), and self-reported functional limitation (standardized item battery). Multivariate analysis was used to control for confounding by age, sex, race, height, educational attainment, and cigarette smoking.


RESULTS
COPD was associated with poorer lower extremity function (mean SPPB score decrement for COPD vs referent -1.0 points; 95% CI, -1.25 to -0.73 pts) and less distance walked during the SMWT (-334 feet; 95% CI, -384 to -282 ft). COPD also was associated with weaker muscle strength in every muscle group tested, including both the upper and lower extremities (P<.0001 in all cases) and with a greater risk of self-reported functional limitation (OR 6.4; 95% CI, 3.7 to 10.9).


CONCLUSIONS
A broad array of physical functional limitations were specifically attributable to COPD. COPD affects a multitude of body systems remote from the lung.
Eisner
Mark D
MD
Division of Occupational and Environmental Medicine and Division of Pulmonary and Critical Care Medicine, Department of Medicine, University of California, San Francisco, CA 94143-0111, USA. mark.eisner@ucsf.edu
Blanc
Paul D
PD
Yelin
Edward H
EH
Sidney
Stephen
S
Katz
Patricia P
PP
Ackerson
Lynn
L
Lathon
Phenius
P
Tolstykh
Irina
I
Omachi
Theodore
T
Byl
Nancy
N
Iribarren
Carlos
C
D000328:Adult; D000368:Aged; D004185:Disability Evaluation; D005260:Female; D006801:Humans; D007407:Interviews as Topic; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D053580:Muscle Strength; D004856:Postural Balance; D029424:Pulmonary Disease, Chronic Obstructive / Q000503:physiopathology*; D012129:Respiratory Function Tests