Background & aims:
Patients with head and neck cancer (HNC) experience high rates of malnutrition and sarcopenia. Bioelectrical impedance analysis (BIA) is a cheap, portable and easy to use body composition method that measures fat free mass (FFM) and fat mass (FM) at the bedside, whereas computed tomography (CT) is viewed as the international gold standard of tissue level body composition analysis. The aim of the current study was to investigate the agreement between BIA and CT in a population of patients with HNC to determine whether BIA is suitable to use in clinical settings.
Patients with HNC undergoing concurrent chemoradiation therapy that were initially recruited as part of a larger randomized control trial were included. Body composition was measured at baseline and three months post treatment. BIA was measured using a single-frequency, foot-to-foot body composition monitor to determine FFM and FM (kg) and CT scans were measured at the L3 vertebra to determine skeletal muscle area and total fat area (cm2) and converted to kilograms using Mourtzakis’ equations. Agreement between methods were compared using Bland Altman at baseline and over time.
101 patients were included (92% male). The mean age was 61 (+/-10) years. FFM and FM baseline comparisons displayed strong linear relationships (r = 0.75, p < 0.000 and r = 0.86, p < 0.000 respectively). At baseline, BIA overestimated FFM (7.7kg) showing wide limits of agreement (26.4kg) and underestimated FM (-3.6kg), displaying evidence of proportional bias and wide limits of agreement. The change between baseline and 3-months post-treatment showed that BIA overestimated FFM (6.7%) and FM (5.7%), with wide limits of agreement.
The results demonstrated poor agreement between BIA and CT at an individual and population level for both FFM and FM when estimating and comparing changes in body composition for patients with HNC.