Abstract
Previous studies suggest a relationship between systemic inflammation and body composition in chronic obstructive pulmonary disease (COPD). We examined the relationships between body composition (fat free mass index (FFMI) kg·m−2 and fat mass index (FMI) kg·m−2) and three plasma inflammatory markers C-reactive Protein (CRP), soluble tumour necrosis factor receptor 1 (sTNF-R1) and osteoprotegerin (OPG) in 409 stable COPD patients (aged 40–75 yrs, Global Initiative for Obstructive Chronic Lung Disease (GOLD) categories II-IV, 249 male) from the Bergen COPD Cohort Study in Norway.
FFMI and FMI were measured by bioelectrical impedance. Plasma CRP (μg·mL−1), sTNF-R1 (pg·mL−1) and OPG (ng·mL−1) were determined by enzyme immunoassays. Correlations and Kruskal–Wallis tests were used for bivariate analyses. Linear regression models were fitted for each of the three markers, CRP, sTNF-R1 and OPG, with FFMI and FMI as explanatory variables including sex, age, smoking habits, GOLD category, hypoxaemia, Charlson Comorbidity Index and inhaled steroid use as potential confounders.
CRP and sTNF-R1 levels correlated positively with both FFMI and FMI. The adjusted regression coefficients for an increase in logCRP per unit increase in FFMI was 1.23 (1.14–1.33) kg·m−2 and 24.9 (11.8–38.1) kg·m−2 for sTNF-R1. Higher FMI was associated with a lower OPG, with adjusted regression coefficient -0.14 (-0.23– -0.04), whereas FFMI was unrelated to OPG.
In conclusion, COPD patients with low FFMI had lower not higher plasma levels of CRP and sTNF-R1, whereas higher fat mass was associated with higher CRP and sTNF-R1 and lower OPG.
Footnotes
Statement of Interest
None declared.
- Received December 8, 2009.
- Accepted April 4, 2010.
- ©ERS 2010