Research

Body composition and functional limitation in COPD

Mark D Eisner^1,2 , Paul D Blanc¹ , Steve Sidney² , Edward H Yelin³ , Phenius V Lathon² , Patricia P Katz³ , Irina Tolstykh² , Lynn Ackerson² and Carlos Iribarren²

¹Division of Occupational and Environmental Medicine and Division of Pulmonary and Critical Care Medicine, Department of Medicine, University of California, San Francisco, USA

²Division of Research, Kaiser Permanente, Oakland, CA, USA

³Institute for Health Policy Studies, Department of Medicine, University of California, San Francisco, USA

author email corresponding author email

Respiratory Research 2007, 8:7doi:10.1186/1465-9921-8-7

Published:	29 January 2007

Abstract

Background

Low body mass index has been associated with increased mortality in severe COPD. The impact of body composition earlier in the disease remains unclear. We studied the impact of body composition on the risk of functional limitation in COPD.

Methods

We used bioelectrical impedance to estimate body composition in a cohort of 355 younger adults with COPD who had a broad spectrum of severity.

Results

Among women, a higher lean-to-fat ratio was associated with a lower risk of self-reported functional limitation after controlling for age, height, pulmonary function impairment, race, education, and smoking history (OR 0.45 per 0.50 increment in lean-to-fat ratio; 95% CI 0.28 to 0.74). Among men, a higher lean-to-fat ratio was associated with a greater distance walked in 6 minutes (mean difference 40 meters per 0.50 ratio increment; 95% CI 9 to 71 meters). In women, the lean-to-fat ratio was associated with an even greater distance walked (mean difference 162 meters per 0.50 increment; 95% CI 97 to 228 meters). In women, higher lean-to-fat ratio was also associated with better Short Physical Performance Battery Scores. In further analysis, the accumulation of greater fat mass, and not the loss of lean mass, was most strongly associated with functional limitation among both sexes.

Conclusion

Body composition is an important non-pulmonary impairment that modulates the risk of functional limitation in COPD, even after taking pulmonary function into account. Body composition abnormalities may represent an important area for screening and preventive intervention in COPD.