Phase Angle and the Diagnosis of Impending Death in Patients with Advanced Cancer: Preliminary Findings

Abstract

Background: Phase angle is a prognostic factor in patients with months of survival, but its accuracy has not been examined in patients with weeks/days of survival. We determined the association between phase angle and survival in patients with advanced cancer admitted to an acute palliative care unit (APCU).

Subjects, materials, and methods: We prospectively assessed phase angle in consecutive patients with advanced cancer admitted to our APCU. We conducted univariate and multivariate survival analyses adjusting for established prognostic factors. Post hoc subgroup analyses examined patients with and without edema.

Results: Among 204 patients, the median overall survival was 10 days (95% confidence interval [CI] 8-11 days). Seventy-four (36%) did not have edema. The median phase angle was 3.7° for the entire cohort, 3.9° for the nonedematous subgroup and 3.6° for the edematous subgroup. In univariate analysis, a low phase angle was associated with decreased survival for the entire cohort (≤3° vs. >3°, median survival 7 vs. 10 days, p = .045) and the nonedematous subgroup (5 vs. 18 days, p < .001) but not the edematous subgroup (9 vs. 9 days, p = .84). In multivariate analysis, phase angle did not reach significance for the entire cohort but remained significant in the nonedematous subgroup (hazard ratio 2.46, 95% CI 1.14-5.31, p < .001). Specifically, phase angle ≤3° had an accuracy of 86% (95% CI 77%-93%) for 3-day survival in patients without edema.

Conclusion: Phase angle had limited prognostic utility in unselected APCU patients but was significant in the nonedematous subgroup. Further studies are required to confirm these preliminary findings.

Implications for practice: In this prospective study involving 204 patients with advanced cancer, phase angle as measured by bioelectric impedance analysis was a significant predictor of mortality independent of known prognostic factors in patients without edema but not patients with edema. Among patients without edema, a phase angle ≤3° had an accuracy of 86% for 3-day survival, which may inform the diagnosis of impending death and potentially end-of-life decision making.

Keywords: Electric impedance; Forecasting; Neoplasms; Palliative care; Prognosis; Survival.

Figure 1.

Study flow diagram. Abbreviation: APCU, acute palliative care unit.

Figure 2.

Kaplan‐Meier survival curves. A phase angle value of 3.0 was identified as the ideal cutoff. A lower phase angle was associated with shorter survival. All 204 patients (A), patients without edema (B), and patients with edema (C).