Background: The purpose of this study was to validate bioelectrical impedance analysis (BIA) using the Geneva equation for fat-free mass (FFM) in patients with head and neck cancer.
Methods: In 24 patients with head and neck cancer, agreement between BIA (FFMBIA ) and dual energy x-ray absorptiometry (FFMDXA ) 1 week before (T0 ), 1 month (T1 ), and 4 months (T2 ) after cancer treatment was analyzed.
Results: FFMBIA did not differ from FFMDXA (mean difference 0.71 ± 1.9, 0.30 ± 1.9, and 0.02 ± 2.1 kg) at any time point. Only at T0 , mean FFM correlated to the difference between FFMDXA and FFMBIA (r = 0.48; p = .017). Limits of agreement were 3.8, 3.7, and 4.1 kg, respectively. Concordance Correlation Coefficients were 0.98 at all time points.
Conclusion: BIA may be used to assess FFM with reasonable validity based on mean-level comparisons, but differences between BIA and DXA may vary by about 4 kg in an individual patient. These results require confirmation in a larger sample of patients with head and neck cancer.
Keywords: bioelectrical impedance analysis; body composition; fat-free mass; head and neck cancer; validity.
Copyright © 2013 Wiley Periodicals, Inc.