Segmental Phase Angles by Bioimpedance as Predictors of Frailty in Hospitalized Older Adults with Cardiovascular Disease: A Cross-Sectional Observational Study

Background/Objectives: Whole-body phase angle has been associated with in-hospital morbidity and mortality, although cut-off points vary. Studies on the relationship between segmental phase angles and frailty in patients with cardiovascular disease are limited. Therefore, we aimed to assess the prognostic value of segmental phase angles in detecting frailty in older adults hospitalized with cardiovascular disease. Methods: A cross-sectional observational study was conducted on hospitalized patients aged ≥60 years with cardiovascular disease. Frailty was identified using Fried's five criteria. Biomarkers (CRP, albumin, hemoglobin), anthropometric parameters, and body composition using segmental electrical bioimpedance (phase angles, body fat, body water, and sarcopenia index) were collected. Associations with frailty were analyzed using logistic regression and Receiver Operating Characteristic (ROC) curves. Sensitivity, specificity, and positive likelihood ratio (LR+) were calculated (95% CI; p<0.05). Results: A total of 157 patients (men: 64.24%; women: 33.76%) were included, with a mean age of 73.23 years (SD=7.91). The prevalence of frailty was 28.66%. In men, the phase angles of the left hemisphere (5.15°) and left leg (4.25°) showed good discriminatory capacity (AUC: 0.66–0.71; LR+: >2). In women, the segments with significance did not exceed an LR+ of 2. Frailty was associated with lower phase angle values in all segments and with biomarkers such as hemoglobin <12 g/dL (p=0.011) and CRP >5 mg/L (p=0.030). Conclusions: Segmental phase angles are moderately useful for identifying frailty in hospitalized older men with cardiovascular disease. Further studies are needed to establish clinically useful cutoffs, especially in women.