Body composition in patients with chronic obstructive pulmonary disease. Comparison between bioelectrical impedance analysis and anthropometry

Malnutrition is associated with pool prognosis ill patients with chronic ob structive pulmonary disease (COPD). Body weight is not a reliable evaluatio n criterium. Body composition which is more useful can be determined routin ely using 2 techniques: skinfold thickness anthropometry (Ant) and bioelect rical impedance analysis (BIA). The validity of this last technique has not been demonstrated in patients with COPD. Fat-free mass (FFM) in 58 patients (51 rneiz, 7 women) with stable COPD (FE VI < 50% of predicted value) was assessed using the 4-skinfold-thickness me thod (Ant) and BIA (Imp). Statistical analysis included correlation analysi s, intraclass correlation coefficient, and the Bland and Altman analysis. Imp-FFM and Ant-FFM correlated well (r = 0.920; p < 0.0001). Intraclass cor relation coefficient was high (r(1) = 0.9065). However the values were scat tered and there was a systematic bias (significant linear regression betwee n the difference in estimates obtained by the 2 methods and the means). As anthropometric measurements are nor reliable in the elderly patients, ou r in results suggest that BIA could be a useful tool to determine FFM in pa tients with COPD. Its validity still has to be tested against a reference m ethod.