Modified creatinine index as a noninvasive tool for the monitoring of muscle mass in peritoneal dialysis

BackgroundThe dialysis process negatively affects skeletal muscle mass and function by disrupting metabolic and nutritional balance. A previous study showed that single time-point measurement of modified creatinine index (MCrI) was a simple and reliable marker of skeletal muscle mass. The present study aims to evaluate whether serial monitoring of MCrI can detect changes in skeletal muscle mass and predict treatment outcomes in patients undergoing peritoneal dialysis (PD).MethodsWe studied 351 new adult PD patients. MCrI values were calculated by a validated formula at baseline and then every 6 months for 2 years. At the same time, lean tissue mass (LTM) was assessed by bioimpedance spectroscopy and fat-free edema-free body mass (FEBM) by traditional creatinine kinetic methods. The patients were followed for 59.2 ± 32.7 months for survival and hospitalization.ResultsWhen the percentage change in LTM (Δ%LTM) was taken as the reference, modified Bland-and-Altman analysis showed that the bias of percentage change of MCrI (Δ%MCrI) was +4.9%, with the limits of agreement -26.6 to +36.4%. When the percentage change in FEBM (Δ%FEBM) was taken as the reference, the bias of Δ%MCrI was -7.0%, with limits of agreement -35.4 to 21.3%. There was no significant association between Δ%MCrI and patient survival, hospital admission, or peritonitis rate.ConclusionsThe change in MCrI does not reliably represent the change in muscle mass in PD patients. Further research is needed to identify other noninvasive method for evaluating muscle mass in the PD population.