Relevance of standardized phase angle and bioelectrical impedance vectors in hospitalized older patients: A cohort study

Background: The prognostic significance of standardized phase angle (StPhA) and bioelectrical impedance vector analysis (BIVA) remains unclear among hospitalized older individuals. Our study aimed to investigate the prognostic significance of StPhA and BIVA patterns concerning overall survival in hospitalized older patients. Methods: A prospective cohort study was conducted among older adults hospitalized in medical or surgical wards. Single-frequency bioelectrical impedance analysis (BIA) was conducted. Using the raw BIA measurements (resistance and reactance), BIVA plots were graphed and StPhA was calculated. In addition, patients underwent assessments for anthropometry, malnutrition, and muscle strength via handgrip strength test. Follow-up was conducted for up to 24 months after the initial data collection to determine the incidence of mortality as the outcome. Results: A total of 168 patients were included in this analysis. They were mostly men, with a median age of 68 years. Onco-hematological diagnoses were the most frequent. Patients with low StPhA exhibited significantly lower body mass index and fat mass (%) (P < 0.05). Analysis of BIVA confidence showed that patients with low StPhA and nonsurvivors exhibited a significant downward shift along the y-axis, indicating less cell mass. BIVA ellipses demonstrated that patients with low StPhA and nonsurvivors were mainly concentrated in the cachexia and anasarca quadrants. Low StPhA was an independent predictor of mortality (hazard ratioadjusted = 2.28; 95% CI, 1.05-4.97). Conclusion: Our study highlights the prognostic significance of StPhA and demonstrates the clinical relevance of using BIVA to estimate body composition/nutrition phenotypes in hospitalized older patients.