Phase angle and standardized phase angle as predictors of 5-year survival in hemodialysis patients

Determine the cut-offs for the phase angle (PhA) and standardized phase angle (SPhA) and evaluate their usefulness as survival predictors in hemodialysis (HD) patients.

A retrospective cross-sectional observational study was conducted in a cohort of 140 HD patients, jointly evaluating clinical, nutritional, and body composition measurements. PhA and SPhA were measured using bioelectrical impedance. Receiver operating characteristic (ROC) curves were applied to identify the optimal cutoff values for PhA and SPhA. Kaplan-Meier and Cox regression analyses assessed the ability of PhA and SPhA to predict 5-year overall survival.

Of the 140 HD patients, 65 were male (46.5%), median age of 74 years (range, 58-91). Higher PhA was in survivors (4.55 ± 0.93) than in non-survivors (3.97 ± 0.99) (P < 0.002). The optimal PhA cutoff was 4° (sensitivity: 73.58%; specificity: 64.71%; AUC: 0.686), and for the SPhA was -1.89 (sensitivity: 75.47%; specificity: 64.71%; AUC: 0.654) (both, P < 0.001). The mortality rate for PhA was 24.3%. The 1-, 3-, and 5-year overall survival rates were 88.0%, 66.0%, and 57.0%, respectively. HD patients with SPhA values of at least -1.89 had an overall 5-year survival rate of 60.0% (P = 0.001). Cox-regression analysis demonstrated that PhA (HR:2.915, 95%CI: 1.561-5.444; P < 0.001) and SPhA (HR: 3.106, 95%CI: 1.655- 5.829; P < 0.001) were predictors of 5-year overall survival in HD.

PhA and SPhA are clinically useful and predict 5-year survival in HD patients. The PhA cutoff of 4° and the SPhA cutoff of -1.89 were sensitive markers for detecting PEW in HD. SPhA may be a more effective nutritional predictor of overall survival than PhA alone. Further research is needed to validate the predictive value of SPhA.