Prediction of sarcopenia among peritoneal dialysis patients using a combination of irisin and phase angle

Background: Sarcopenia is associated with significant morbidity and mortality in patients undergoing peritoneal dialysis (PD). Three different tools must be applied to measure the three indices for diagnosing sarcopenia. Considering the cumbersome diagnostic steps and multi-layered mechanisms underlying sarcopenia, we combined new biomarker with bioelectrical impedance analysis (BIA) data to predict PD sarcopenia.

Methods: Patients underwent regular PD were asked to complete sarcopenia screening, including appendicular skeletal muscle mass, handgrip strength, and the 5-time chair stand time test according to the newly revised diagnosis consensus of Asian Working Group for Sarcopenia (AWGS2019). Serum was collected for centralized detection of the irisin levels. BIA data, especially the phase angle (PhA), as well as patient's general clinical information, dialysis related indices, laboratory data and body composition data were recorded.

Results: Among 105 enrolled PD patients (41.0% men, mean age 54.2 ± 8.89 years), the sarcopenia prevalence was 31.4% and the sarcopenic obesity was 8.6%. Binary regression analysis showed that serum irisin concentrations (OR = 0.98; 95% CI,0.97-0.99; p = 0.002), PhA (OR = 0.43; 95% CI, 0.21-0.90; p = 0.025) and body mass index (BMI) (OR = 0.64; 95% CI, 0.49-0.83; p = 0.001) were independently associated with PD sarcopenia. The AUC of the combination use of serum irisin concentrations and PhA for predicting PD sarcopenia was 0.925 with a sensitivity of 100% and specificity of 84.0% in male and was 0.880 with a sensitivity of 92.0% and specificity of 81.5% in female. PD sarcopenia score=1533.48+-0.75*Handgrip strength+4.63*BMI+-18.07*Total body water +-11.87*Extra-cellular water / total body water +9.26*Fat free mass index+-83.41*PhA+22.42*Albumin/Globulin+-26.38*blood phosphorus+-17.04*Total cholesterol+-29.02*Triglyceride+-0.29*Prealbumin+-0.17*Irisin.

Conclusions: Sarcopenia is relatively common among PD patients. The combination of serum irisin concentrations and PhA facilitated the rapid prediction of PD sarcopenia and could serve as an optimal screening tool for PD sarcopenia in clinical settings.