Bioimpedance phase angle predicts muscle function, quality of life and clinical outcome in maintenance hemodialysis patients

Background/Objectives: The association of bioimpedance phase angle (PA), as a measure of nutritional status, with muscle function, health-related quality of life (QoL) and subsequent clinical outcomes in maintenance hemodialysis (MHD) patients. Subjects/Methods: A 2-year prospective observational study on 250 MHD outpatients (36.8% women) with a mean age of 68.7±13.6 years. Prospective all-cause and cardiovascular (CV) hospitalization and mortality, malnutrition-inflammation score (MIS), handgrip strength (HGS), bioimpedance and short form 36 (SF-36) QoL scores were the study's measurements. Results: Across the three PA tertile groups, HGS was incrementally higher in the higher PA tertiles (P<0.001), maintaining this order in both male (r=0.38, P<0.001) and female patients (r=0.36, P<0.001). Better self-reported QoL was noted with higher PA values. This trend was prominent in total score (P<0.001), mental health (P=0.005) and physical health (P<0.001) dimensions, and in most of the SF-36 scales. For each 1° increase in baseline PA, the first hospitalization hazard ratio (HR) was 0.79 (95% confidence interval (CI), 0.68-0.91) and first CV event HR was 0.70 (95% CI, 0.52-0.95); all-cause death HR was 0.63 (95% CI, 0.48-0.81) and CV death HR was 0.64 (95% CI, 0.44-0.91). Associations between PA and morbidity risk continued to be significant after adjustments for various confounders, but the association between PA and mortality risk was abolished after adding MIS to the multivariable model. Conclusions: For the MHD population, PA emerged as a useful predictor for impaired muscle function, health-related Qol, upcoming hospitalizations and mortality.