The bioimpedance phase angle is more useful than sarcopenia as a predictor of falls in patients with rheumatoid arthritis: Results from a 2-y prospective cohort study

Abstract

ObjectivesThe phase angle (PhA) is an index derived by bioelectrical impedance analysis that reflects the fragility of cell membranes, muscle mass, muscle strength, and nutritional status, and a decrease in PhA might be associated with falls. This study aimed to investigate the relationships of the PhA with sarcopenia and falls in patients with rheumatoid arthritis (RA). MethodsData from a prospective cohort study of 189 patients with RA (age 66.5 ± 13.3 y; 80% women) were analyzed. PhA, muscle mass, and grip strength (GS) were evaluated. Sarcopenia was assessed using the Asian Working Group for Sarcopenia 2014 criteria. The correlation between PhA and GS was investigated, and the cutoff value of the PhA for falls during a 2-y period was estimated with a receiver operating characteristic curve analysis. The effects of the PhA and sarcopenia on falls were examined with a Cox proportional hazards model. ResultsOf the 189 patients, 48 (25.4%) had falls. The PhA was significantly positively correlated with GS (r = 0.58; P < 0.001). The cutoff values for the PhA for falls were 4.06° for women and 5.26° for men. In the Cox proportional hazards model adjusted for sex, age, disease activity, glucocorticoid use, and activities of daily living at baseline, the hazard ratio for falls was significantly higher when the PhA was below the cutoff value at baseline (hazard ratio: 2.29; 95% confidence interval, 1.18–4.45). Sarcopenia was not a significant risk factor for falls. ConclusionsThe PhA might be a useful surrogate marker to predict falls in patients with RA.