Posttransplant muscle mass measured by urinary creatinine excretion rate predicts long‐term outcomes after liver transplantation

Long-term survival in orthotopic liver transplant (OLT) recipients remains impaired due to many contributing factors, among which a low pre-transplant muscle mass (or sarcopenia). However, influence of post-transplant muscle mass on survival is currently unknown. We hypothesized that post-transplant urinary creatinine excretion rate (CER), an established non-invasive marker of total body muscle mass, is associated with long-term survival after OLT. In a single-center cohort study of 382 adult OLT recipients, mean±standard deviation CER at 1 year post-transplantation was 13.3±3.7 mmol/24h in men and 9.4±2.6 mmol/24h in women. During median follow-up for 9.8y (interquartile range 6.4-15.0y), 104 (27.2%) OLT recipients deceased and 44 (11.5%) developed graft failure. In Cox regression analyses, as continuous variable, low CER was associated with increased risk for mortality (HR=0.43, 95%CI: 0.26-0.71, P=0.001) and graft failure (HR=0.42, 95%CI: 0.20-0.90, P=0.03), independent of age, sex, and body surface area. Similarly, OLT recipients in the lowest tertile had an increased risk for mortality (HR=2.69; 95%CI: 1.47-4.91, P=0.001) and graft failure (HR=2.77, 95%CI: 1.04-7.39, P=0.04), compared to OLT recipients in the highest tertile. We conclude that 1-year post-transplant low total body muscle mass is associated with long-term risk of mortality and graft failure in OLT recipients. This article is protected by copyright. All rights reserved.