Phase angle as a predictor of mortality in elderly patients with multimorbidity: a matched case-control study.

Abstract

We aimed to investigate the value of phase angle (PhA) as a prognostic marker for mortality in elderly patients with multimorbidity using a matched case-control study. This study was conducted with patients 70 years of age or older with multimorbidity at Beijing Geriatric Hospital. The body composition parameters including PhA were determined using bioelectrical impedance analysis. Common hematological indices were determined using blood tests. The outcome was mortality 1 year after admission. A multivariate logistic regression analysis was employed to identify independent risk factors for death. A receiver-operating characteristic (ROC) curve analysis was used to evaluate the performance of risk factors in predicting death. A total of 30 deceased patients were included in the death group. The living patients were matched 1:1 with the deceased patients in age, gender, and Cumulative Illness Rating Scale-Geriatric score to generate a survival group of 30. The death group exhibited higher levels of blood urea nitrogen and extracellular water to total body water ratio and lower levels of PhA and prealbumin than the survival group. The multivariate logistic regression analysis identified PhA as the only independent risk factor for mortality (OR = 3.296, 95% CI [1.201-9.044], P < 0.05). For the ROC curve analysis, PhA had an area of 0.854 (95% CI [0.755-0.955], P = 000). The Youden index was 0.700, and the optimal cutoff value associated with the Youden index was 2.45°. PhA serves as a good prognostic marker for mortality in elderly patients with multimorbidity.