Validation of a bioelectrical impedance analysis system for body composition assessment in patients with COPD

Objective: To investigate the validity of an eight-contact electrode bioelectrical impedance analysis (BIA) system within a household scale for assessing whole body composition in COPD patients. Methods: Seventeen patients with COPD (mean age = 67 ± 8 years; mean FEV₁ = 38.6 ± 16.1% of predicted; and mean body mass index = 24.7 ± 5.4 kg/m²) underwent dual-energy X-ray absorptiometry (DEXA) and an eight-contact electrode BIA system for body composition assessment. Results: There was a strong inter-method correlation for fat mass (r = 0.95), fat-free mass (r = 0.93), and lean mass (r = 0.93), but the correlation was moderate for bone mineral content (r = 0.73; p < 0.01 for all). In the agreement analysis, the values between DEXA and the BIA system differed by only 0.15 kg (−6.39 to 6.70 kg), 0.26 kg (−5.96 to 6.49 kg), −0.13 kg (−0.76 to 0.50 kg), and −0.55 kg (−6.71 to 5.61 kg) for fat-free mass, lean mass, bone mineral content, and fat mass, respectively. Conclusions: The eight-contact electrode BIA system showed to be a valid tool in the assessment of whole body composition in our sample of patients with COPD. (author)