Department of General Surgery, The Affiliated Jinling Hospital of Nanjing Medical University, Nanjing, China; Department of General Surgery, The Affiliated People's Hospital of Jiangsu University, Zhenjiang, China.
Department of General Surgery, Nanjing Jinling Hospital, Affiliated Hospital of Medical School, Nanjing University, Nanjing, China.
Nutrition. 2024 May;121:112363. doi: 10.1016/j.nut.2024.112363. Epub 2024 Jan 22.
Low muscle mass was significantly correlated with poor clinical outcomes in cancer patients. This study aimed to compare the differences between bioelectrical impedance analysis (BIA) and computed tomography (CT) in measuring skeletal muscle mass and detecting low muscle mass in patients with gastric cancer (GC).
This cross-sectional study included a total of 302 consecutive patients diagnosed with GC at our institution from October 2021 to March 2023. CT images were analyzed at the L3 level to obtain the cross-sectional area of skeletal muscle, which was subsequently used for calculating whole-body skeletal muscle mass via the Shen equation and skeletal muscle tissue density. BIA was utilized to measure skeletal muscle mass using the manufacturer's proprietary algorithms. Skeletal muscle mass (kg) was divided by height squared (m) to obtain skeletal muscle index (SMI, kg/m). Pearson's correlation coefficient was performed to assess the correlation between SMI measured by BIA and CT. The agreement between the two methods was assessed using Bland-Altman analyses. The clinically acceptable agreement was defined as the 95% limits of agreement (LOA) for the percentage bias falling within ± 10%. The area under the receiver operating characteristic curve (AUC) was used to evaluate the performance of BIA in identifying low muscle mass.
A total of 59 patients (19.5%) were identified as having low muscle mass based on CT analysis, whereas only 19 patients (6.3%) met the criteria for low muscle mass according to BIA analysis. BIA-measured SMI showed a strong positive correlation with CT-measured SMI in all patients (r = 0.715, P < 0.001). With Bland-Altman analysis, there was a significant mean bias of 1.18 ± 0.96 kg/m (95% CI 1.07-1.29, P < 0.001) between SMI measured by BIA and CT. The 95% LOA for the percentage bias ranged from -7.98 to 33.92%, which exceeded the clinically acceptable range of ± 10%. A significant difference was observed in the mean bias of SMI measured by BIA and CT between patients with and without GLIM malnutrition (1.42 ± 0.91 kg/m versus 0.98 ± 0.96 kg/m, P < 0.001). The cut-off values for BIA-measured SMI in identifying low muscle mass using CT as the reference were 10.11 kg/m for males and 8.71 kg/m for females (male: AUC = 0.840, 95% CI: 0.772-0.908; female: AUC = 0.721, 95% CI: 0.598-0.843).
Despite a significant correlation, the values of skeletal muscle mass obtained BIA and CT cannot be used interchangeably. The BIA method may overestimate skeletal muscle mass in GC patients compared to CT, especially among those with GLIM malnutrition, leading to an underestimation of low muscle mass prevalence.
低肌肉量与癌症患者的临床预后不良显著相关。本研究旨在比较生物电阻抗分析（BIA）和计算机断层扫描（CT）在测量胃癌（GC）患者骨骼肌量和检测低肌肉量方面的差异。
这是一项横断面研究，共纳入了 2021 年 10 月至 2023 年 3 月期间在我院确诊为 GC 的 302 例连续患者。在 L3 水平分析 CT 图像以获得骨骼肌的横截面积，随后使用 Shen 方程计算全身骨骼肌量和骨骼肌组织密度。BIA 用于使用制造商的专有算法测量骨骼肌量。将骨骼肌量（kg）除以身高的平方（m）以获得骨骼肌指数（SMI，kg/m）。Pearson 相关系数用于评估 BIA 测量的 SMI 与 CT 之间的相关性。使用 Bland-Altman 分析评估两种方法之间的一致性。将可接受的临床一致性定义为百分比偏差的 95%置信区间（LOA）落在±10%内。使用受试者工作特征曲线（AUC）下面积评估 BIA 识别低肌肉量的性能。
根据 CT 分析，共有 59 例（19.5%）患者被确定为低肌肉量，而根据 BIA 分析，仅有 19 例（6.3%）患者符合低肌肉量标准。BIA 测量的 SMI 与所有患者的 CT 测量的 SMI 呈强正相关（r=0.715，P<0.001）。通过 Bland-Altman 分析，BIA 和 CT 测量的 SMI 之间存在显著的平均偏差，为 1.18±0.96 kg/m（95%置信区间 1.07-1.29，P<0.001）。百分比偏差的 95%LOA 范围为-7.98%至 33.92%，超出了可接受的±10%范围。在有和没有 GLIM 营养不良的患者之间，BIA 和 CT 测量的 SMI 的平均偏差有显著差异（1.42±0.91 kg/m 与 0.98±0.96 kg/m，P<0.001）。以 CT 为参考，BIA 测量的 SMI 用于识别低肌肉量的截断值为男性 10.11 kg/m 和女性 8.71 kg/m（男性：AUC=0.840，95%置信区间：0.772-0.908；女性：AUC=0.721，95%置信区间：0.598-0.843）。
尽管存在显著相关性，但 BIA 和 CT 获得的骨骼肌量值不能互换使用。与 CT 相比，BIA 方法可能会高估 GC 患者的骨骼肌量，尤其是在 GLIM 营养不良患者中，从而低估低肌肉量的患病率。
