Bioelectrical impedance-derived phase angle (PhA) in people living with obesity: Role in sarcopenia and comorbidities

Obesity is characterized by alterations in fat and muscle mass. Phase angle (PhA) is considered an index of muscle mass, and is related to comorbidities in SO. This work aimed to assess the relationship between PhA, muscle mass, inflammation, and comorbidities in obesity.

We included 198 outpatients with obesity (BMI≥30) divided into tertiles according to PhA distribution (<5°, 5°-6°, >7°). Body composition was analyzed using bioimpedance (Tanita MC-780P Multi-Frequency Segmental Body Composition Analyzer). Quantitative variables were compared using the Kruskal-Wallis test and qualitative variables using the chi-square test. A correspondence analysis was built to show the influence of qualitative variables on subjects in each tertile. Patients in the lowest tertile had the lowest skeletal muscle mass and appendicular skeletal muscle mass index (ASMI); the highest inflammatory index (albumin and derived neutrophil-to-lymphocyte ratio, Alb-dNLR); and the highest percentage of individuals with a history of type 2 diabetes mellitus (T2DM), chronic kidney disease (CKD), and heart failure (HF). The correspondence analysis showed an association between the lowest tertile and presence of HF with preserved ejection fraction (HFpEF) and CKD. On the logistic regression model, ASMI (OR 0.9, 95%CI 0.85-0.95, p = 0.0004), Alb-dNLR (OR 1.04, 95%CI 1.04-16.4, p = 0.04) and HFpEF and T2DM were significantly associated with the lowest PhA.

Identifying high-risk individuals living with obesity is a priority. These results show that lower PhA is related to inflammation, poorer skeletal muscle mass and consequently, their impact on obesity-related comorbidities and clinical outcomes.