Phase angle, nutritional status, and mortality in systemic sclerosis: An exploratory pilot study

Systemic sclerosis (SSc) is a rare autoimmune disease characterized by microvascular damage and fibrosis of the skin and internal organs. Among SSc complications, changes in nutritional status have a negative effect on quality of life and predispose patients to malnutrition. The aim of this exploratory pilot study was to examine whether bioelectrical impedance analysis-derived phase angle (PhA) is a parameter of nutritional status and a marker of mortality in patients with SSc.

Consecutive adult patients with SSc were included in the study. Biochemical analyses, anthropometric data, and bioelectrical impedance analysis assessments were recorded at the time of enrollment. The Malnutrition Universal Screening Tool (MUST) and Global Leadership Initiative on Malnutrition (GLIM) were applied to assess nutritional status.

A total of 104 patients with SSc (88 women; median age: 55 y [interquartile range (IQR), 45.5- 66 y]) were enrolled. In patients with SSc and high malnutrition risk according to MUST, mean values of PhA were significantly lower than those of patients with SSc and low malnutrition risk (4° [IQR, 3.7°-4.4°] vs 4.6° [IQR, 4.2°-5.1°]; P = 0.004). Patients with SSc and malnutrition according to the GLIM criteria showed significantly lower PhA than patients with SSc but without malnutrition (3.8° [IQR, 3.5°-4.3°] vs 4.6° [IQR, 4.2°-5.1°]; P < 0.0001). Kaplan-Meier curves demonstrated that overall survival was significantly shorter (34.57 mo [±13.35] vs 48 mo [±0]; P = 0.001) in patients with SSc and PhA <3.75°. In the multivariate analysis, only PhA was a predictive factor for death (hazard ratio: 0.283; 95% confidence interval, 0.083-0.965; P = 0.044).

The data obtained suggest that lower PhA values in patients with SSc are associated with an increased malnutrition risk with MUST, malnutrition with GLIM, and increased mortality. Additional studies are necessary to confirm these preliminary results.