Phase Angle Is A Better Predictor Of Survival Than Muscle Mass In Advanced Cancer

1.Discuss bioelectrical impedance parameters, resistance, capacitance, and phase angle.2.Discuss how the bioelectrical impedance parameters measure clinically important signs such as muscle loss and membrane function.3.Discuss the relationship of phase angle and changes in phase angle during hydration with patient survival. I. Background. Single frequency 50 KHZ bioelectrical impedance analysis (BIA) measures reactance, resistance, and phase angle (PA). PA is determined by quantity and quality of membrane function. Low PA inversely correlates with C-reactive protein and directly with survival in cancer. A BIA equation for predicting smooth muscle mass (SMM) has been validated by MRI with a correlation (r2=0.86 SE 2.71 kg, 9%). II. Research Objectives. We compared survival predictability of SMM with PA during hydration. III. Method. Fifty individuals with advanced cancer underwent daily BIA for 3 days by standard technique during hydration. Resistance at day 1 was used to calculate SMM using the equation SM (kg)=(HT2/R×0.401)+(gender [0 or 1]×3.875)+(age×0.071)+5.102. Spearman correlations were used for comparisons. Kaplan-Meier survival estimate at 30- and 60-days post-hydration was the outcome. Hazard ratios based on Cox Proportional Hazards model were calculated. IV. Result. Patient-reported weight loss (P=.014) and increased PA over 3 days (P=.01) predicted poorer survival. Higher PA on day 1 (P=.057) and weight gain during hydration (P=.007) predicted better survival. HR for mortality increased by 1.17 for increased PA dL-3, 0.7 for weight gain. SMM did not correlate with survival (HR 1.0, P=.82). Assuming the change in resistance from day 1–3 changes the estimate of skeletal muscle mass, neither D3 skeletal muscle mass nor change in day 1–3 SMM predicted survival (HR 1.04 and HR 1.01, respectively) (P=.96 and P=.88). V. Conclusion. Phase angle is determined by qualitative cell membrane function and is a better predictor of survival than SMM. VI. Implications for Research, Policy, or Practice. BIA-determined phase angle predicts survival independent of skeletal muscle mass. PA should be compared to standard palliative prognostic indices to see if it is an independent prognostic variable. Physical Aspects of Care