Comparison of visceral fat area measured by CT and bioelectrical impedance analysis in Chinese patients with gastric cancer: a cross-sectional study

OBJECTIVES: Bioelectrical impedance analysis (BIA) is a simple and inexpensive method to estimate body composition. However, the accuracy of BIA is unknown. We aimed to assess the accuracy of BIA in estimating visceral fat area (VFA) in patients with gastric cancer. STUDY DESIGN: This was a cross-sectional study comparing the accuracy of BIA in estimating VFA with the gold standard method measured by CT. VFA was measured in enrolled patients both by CT and BIA. VFA by CT at umbilical level ≥100 cm(2) was considered as visceral obesity. Reliability between the two methods was assessed by intraclass correlation coefficient (ICC) and consistency was assessed by Bland-Altman method (95% limits of agreement). The area under the receiver operating characteristic curve (AUROC) was used to assess the performance of BIA in diagnosing visceral obesity. SETTING: The study was conducted in China. PARTICIPANTS: From 1 January 2017 to 1 December 2018, a total of 157 patients diagnosed with gastric cancer were enrolled. RESULTS: Overall, VFA by CT and BIA in patients was 84.39±46.43 cm(2) and 71.94±22.44 cm(2), respectively. VFA estimated by BIA was positively correlated with VFA measured by CT using Pearson’s test (r=0.650, p<0.001). Overall, ICC for the two methods was 0.675. The mean bias between the two measurements was 12.45±36.13 cm(2). The 95% limits of agreement ranged from −58.36 cm(2) to 83.26 cm(2). The cut-off value for diagnosing visceral obesity by BIA was 81 cm(2) (AUROC: 0.822, p<0.001, 95% CI 0.758 to 0.887). CONCLUSIONS: VFA measured by BIA showed satisfactory reliability with that measured by CT. However, the absolute values of the two methods were not interchangeable. The cut-off value for VFA by BIA in diagnosing visceral obesity was 81 cm(2) for patients with gastric cancer in the Chinese population.