Bioelectric impedance spectroscopy underestimates fat-free mass compared to dual energy X-ray absorptiometry in incurable cancer patients

Abstract

Background/Objectives: Weight loss is frequently seen in advanced cancer. Bioelectrical impedance spectroscopy (BIS) is a convenient method for estimating body composition. We examined in a prospective, comparative study if BIS could accurately estimate fat-free mass (FFM) in cancer patients compared to dual-energy X-ray absorptiometry (DXA). Subjects/Methods: The study was based on 132 consecutive incurable cancer patients with solid tumours in a University hospital outpatient clinic. Comparison of FFM from DXA and BIS with standard and revised equations. Bland-Altman plots, t-tests and linear regression analysis were used to evaluate agreement and differences between methods. Results: BIS significantly underestimated mean FFM with 7.6 ± 4.7 kg compared to DXA (Po0.001). Bias was significantly correlated to % weight loss (r ¼ 0.32), systemic inflammation as measured by C-reactive protein (r ¼ 0.29), malnutrition as assessed by low insulin-like growth factor-1 (r ¼ À0.23) and inversely to the per cent body fat estimated by DXA (P ¼ À0.61) and body mass index (BMI; r ¼ À0.30). Revised BIS equations taking BMI into account reduced bias significantly but still with great individual variation. Conclusions: BIS by standard equations grossly underestimates FFM compared to DXA in cancer patients. This bias is related to weight loss, malnutrition and systemic inflammation. Revised equations improved FFM estimates, but with large individual variation. Thus, BIS with standard equations is not suitable to estimate FFM in patients with cachexia, inflammation and malnutrition.

Evolution of bioimpedance: a circuitous journey from estimation of physiological function to assessment of body composition and a return to clinical research

“…Although no significant differences were found between methods, very wide limits of agreement (B10 kg) for BIS predictions were observed for all groups, which suggests the limited clinical use of BIS for patients with end-stage renal disease. Ellegård et al 49 found that BIS significantly underestimated FFM in cancer patients who had undergone large weight losses. The bias of the BIS prediction was significantly correlated with percent weight loss and biochemical indices of malnutrition and weight loss.…”

Measuring body composition using the bioelectrical impedance method can predict the outcomes of gemcitabine-based chemotherapy in patients with pancreatobiliary tract cancer

“…In addition, this method has been reported to correlate extremely well with the evaluation of body composition by computed tomography, magnetic resonance imaging and dual energy X-ray absorptiometry (15,(20)(21)(22)50,51). The current findings indicate that regularly assessing the body composition, using the BI method, of patients with pancreatobiliary tract cancer receiving GEM-based chemotherapy is a useful adjunct index for understanding pathological conditions and for predicting the continuation of chemotherapy treatment.…”

The value of bioelectrical impedance analysis and phase angle in the evaluation of malnutrition and quality of life in cancer patients—a comprehensive review

“…14 Furthermore, it has been shown that BIS and BIA frequently underestimate body composition variables in cancer patients compared with dual-energy X-ray absorptiometry. 41 Some of these deviations can be compensated for by using adequate mathematical transformations accounting for BMI or weight of the patient but phase angle and FFM may deviate significantly between individuals. However, another small exploratory study in 24 patients with head and neck cancer compared the FFM measured via BIA and dual-energy X-ray absorptiometry over the course of radiation treatment and did not find a significant difference between the measurement methods.…”