Screening effect of phase angle and calf circumference in different stages of sarcopenia in patients with maintenance hemodialysis.

BACKGROUND: Complicated testing procedures, high costs and heavy clinical workloads limit routine sarcopenia screening. Patients with different sarcopenia stages present distinct clinical manifestations, so early screening and timely intervention are essential. This study aimed to explore the screening efficiency of phase angle (PhA) and calf circumference (CC) for staged sarcopenia in maintenance hemodialysis (MHD) patients and develop a simple scoring tool. METHODS: This prospective cross-sectional study was conducted from September to December 2023 at the Wenjiang Hemodialysis Center, Department of Nephrology, West China Hospital, Sichuan University, Chengdu, China. Sarcopenia staging followed the 2019 Asian Working Group for Sarcopenia (AWGS) criteria. Receiver operating characteristic (ROC) curve analysis was used to calculate the area under the curve. A simple scoring tool was established based on the optimal cut-off points of CC and PhA. In addition to sensitivity and specificity, positive predictive value (PPV), negative predictive value (NPV), positive likelihood ratio (LR+), and negative likelihood ratio (LR-) were computed for each screening marker to fully characterize diagnostic efficiency. RESULTS: For possible sarcopenia, the area under the receiver operating characteristic curve (AUC) of PhA was 0.680 (95% confidence interval [CI]: 0.613-0.747), with a sensitivity of 64.29% and specificity of 66.17% (cut-off value: 5.6 °). The AUC of the simple scoring tool was 0.598 (95%CI: 0.531-0.664), with a sensitivity of 53.57% and specificity of 67.67% (cut-off value: 1 point). For sarcopenia, the AUC of CC was 0.771 (95%CI: 0.605-0.937), with a sensitivity of 66.67% and specificity of 81.36% (cut-off value: 29 cm). The AUC of the simple scoring tool was 0.789 (95%CI: 0.658-0.920), with a sensitivity of 66.67% and specificity of 83.90% (cut-off value: 1 point). For severe sarcopenia, the AUC of CC was 0.880 (95%CI: 0.809-0.950), with a sensitivity of 93.33% and specificity of 73.04% (cut-off value: 30 cm). The AUC of PhA was 0.865 (95%CI: 0.773-0.957), with a sensitivity of 86.67% and specificity of 78.26% (cut-off value: 4.9 °). The AUC of the simple scoring tool was 0.911 (95%CI: 0.865-0.958), with a sensitivity of 80.00% and specificity of 90.00% (cut-off value: 1 point). CONCLUSIONS: The simple scoring tool showed improved screening performance as sarcopenia severity increased, with a consistent cut-off of 1 point. CC and PhA can be used for staged sarcopenia screening in MHD outpatients. With high negative predictive values, these indicators are suitable for preliminary exclusion screening at the bedside rather than definitive diagnosis. However, given the limited number of sarcopenia cases in this single-center study, this scoring tool should be considered exploratory and requires validation in larger independent cohorts before routine clinical implementation. TRIAL REGISTRATION: Chinese Clinical Trial Registry (ChiCTR2100051111), registered on 2021-09-13.