The phase angle before transplantation can predict the status of low muscle mass after kidney transplantation.

Abstract

This study aimed to evaluate the association between phase angle, muscle strength, and muscle mass in patients undergoing kidney transplantation. Patients whose pre- and follow-up phase angles were measured after kidney transplantation were enrolled. Phase angle and body composition were measured using a multi-frequency bioimpedance analysis device before and at 7 and 14days and 3, 6, and 12months after transplantation. Muscle strength was evaluated using handgrip strength (HGS). Low HGS was defined as < 28kg in males and < 18kg in females. Low muscle mass was defined as an appendicular lean mass index of < 7.0kg/m2 in males and < 5.7kg/m2 in females. Eighty-eight patients (mean age 52.3 ± 10.1years) were analyzed. The mean phase angle of pre-transplantation was 5.0 ± 1.0°. Body fat percentage was significantly higher at 6 and 12months after transplantation than pre-transplantation (P < 0.0001). Twelve months after kidney transplantation, the prevalence of low HGS decreased (pre-transplantation vs. 12months post-transplantation: 28.4% vs. 17.0%), and the prevalence of low muscle mass (pre-transplantation vs. 12months post-transplantation: 21.6% vs. 28.4%) increased. The pre-transplantation phase angle was significantly associated with low muscle mass at 12months after kidney transplantation (odds ratio [OR]: 0.34; 95% confidence interval [CI]: 0.16-0.72; P = 0.005). The pre-transplantation phase angle was not significantly associated with low HGS (OR: 0.37; 95% CI 0.12-1.17; P = 0.090) 12months after kidney transplantation. Pre-transplantation phase angle can predict muscle mass status 12months after kidney transplantation.