RationaleIn bioelectrical impedance analysis (BIA) measurements, one pair of electrodes is typically placed dorsal on the right hand (position A) and one pair on the foot. In patients with fragile skin, scars or wounds, this dorsal hand placement is not always possible. This study compares agreement of BIA measurements at seven alternative placements with position A. MethodsBIA measurements were performed with the Bodystat-500 using eight combinations of hand electrodes: at the dorsal side of the hand (position A) or dorsal side hand-forearm (position B and C); at the palmar side of the hand (position D) or palmar side hand-forearm (position E and F) or mixed palmar-dorsal side of the hand (position G and H). ICCs were used to compare alle outcomes to position A. Changes in fat mass ∆FM, fat-free mass ∆FFM and appendicular skeletal muscle mass ∆ASMM were calculated using Kyle’s formula.ResultsSeventy healthy Caucasian participants were measured: median age 22 years, IQR 21-23; mean BMI 22.8 ± 2.5 kg/m². Electrode positions D,G and H showed an ICC 0.99-1.00 for ∆FM, ∆FFM and ∆ASMM with minimal changes in ∆FFM and ∆FM: 0.1–0.4 kg ± 0.3 kg and ∆ASMM: 0.0–0.2 kg ± 0.2 kg. Measurements at position B, C, E, and F showed significant and clinically relevant differences with ∆FM and ∆FFM: 3.8–4.0 kg ± 1.1 kg and ∆ASMM: 2.0–2.1 kg ± 0.6 kg, with ICCs 0.96-0.97.ConclusionAlternatively to the typical electrode placement on the dorsal side of the hand, this study demonstrates that three alternative placements results in an excellent agreement with only minimal changes in FFM, FM and ASMM. In practice, placing electrodes at more proximal positions on the forearm should be avoided. Alternatively, we recommend a mixed or palmar electrode placement on the hand.
Assessment and monitoring of fat-free mass (FFM) is of clinical importance, because FFM is reflective of body cell mass, the total mass of protein-rich, metabolically active cells which is affected during malnutrition and therefore related to clinical outcome.Bioelectrical impedance analysis (BIA) is a non-invasive, portable and inexpensive method to assess body composition. Currently validity of BIA in head and neck cancer patients is unknown. Therefore, we tested our hypothesis that BIA, using the Geneva equation, is a valid method to assess FFM in head and neck cancer patients.
