Phase angle as a prognostic marker in patients with critical illness

Abstract

Background: Phase angle (PA) is interpreted as an indicator of cell membrane integrity and a prognostic indicator in some clinical situations. This study aims to evaluate PA as a prognostic marker in critically ill patients admitted to the intensive care unit (ICU) and associate this marker with length of hospital stay, mortality, and clinical scores.

Methods: A cohort study was conducted with 95 patients aged ≥18 years admitted to the ICU, who were assessed in terms of prognostic indexes (Acute Physiology and Chronic Health Evaluation II [APACHE II] and Sequential Organ Failure Assessment [SOFA]), clinical evolution (ICU discharge, death, and length of ICU stay), and PA.

Results: Patients were predominantly male (63.1%) and had a mean age of 63.7 ± 14.6 years; length of stay of 4 days (range, 3-9 days); mortality of 15.8%; mean APACHE II and SOFA scores of 17.3 ± 8.2 and 6.1 ± 3.1 points, respectively; and mean PA of 4.91 ± 1.36°. An association was observed between females and PA <5.1° (P = .035), which was the cutoff point determined from the receiver operating characteristic curve. PA was correlated with APACHE II score (r = -0.241; P = .02). This correlation became moderate only when patients without sepsis were considered (r = -0.506; P < .001).

Conclusions: PA seems to be a good prognostic marker for patients without sepsis. The weak correlation between PA and APACHE II score and the lack of association with other clinical outcomes are limitations for interpreting the prognostic value of PA in the entire study sample.

Keywords: bioeletrictrical impedance analysis; body composition; critical illness; phase angle.