Low psoas muscle index as an unfavorable factor in children with end-stage liver disease undergoing liver transplantation

Sarcopenia is common in cirrhotic adults and associated with waitlist mortality and worse outcome after liver transplantation. Psoas muscle mass has been used to define sarcopenia. Therefore, we aimed to determine the association between psoas muscle mass and waitlist mortality as well as post-transplant outcome in children with end-stage liver disease. Medical records and abdominal imaging of pediatric liver transplant candidates during 2010-2019 were reviewed. A subset of images was measured by two radiologists to determine inter-rater reliability. Psoas muscle surface area was determined at intervertebral lumbar disk 3-4 (L3-4) and 4-5 (L4-5) levels. PMI was calculated by psoas muscle surface area divided by height squared. We included 105 children, most with biliary atresia (84%). Patients with waitlist mortality had lower PMI compared to the ones who survived to transplantation (PMI at L3-4 levels 352.8 +/- 162.5 vs. 416.8 +/- 136.2 mm(2)/m(2) and at L4-5 levels 497.3 +/- 167.8 vs. 571.4 +/- 163.4 mm(2)/m(2), both p = .04), but not in the multivariate analyses. For transplanted patients (n = 75), a higher rate of re-operation (39% vs. 15%, p = .03) and longer hospital stay (53 vs. 45 days, p = .02) were found in patients with lower PMI. Lower PMI is associated with higher re-operation rate and longer hospital stay following transplantation, but not waitlist mortality. PMI may be taken into consideration with other biomarkers to predict post-transplant complications.