Backgrounds: Sarcopenia is defined as loss of skeletal muscle strength, mass, and function. It has been reported as a significant risk factor for outcomes after Liver transplantation (LT) as well as waitlist mortality in end-stage liver disease patients. Although there are various imaging modalities and measurement methods for diagnosing sarcopenia, the gold standard is not clear. The purpose of this study is to analyze the effect of sarcopenia on outcome in LT patients using previously known third lumbar (L3)-skeletal muscle index (SMI) cut-off values and newly calculated anterior thigh (AT)-SMI cut-off values.

Method: Three hundred forty-one patients who underwent living and deceased donor liver transplantation in our center from Jan 2018 to Dec 2020 were analyzed. L3-SMI and AT-SMI were obtained by measuring preoperative computed tomography scans with semiautomatic software. For L3-SMI, the cut-off values reported in other previous studies were applied (42 cm2/m2 in males, 38 cm2/m2 in females). For AT-SMI, the optimal cut-off value was obtained by the ROC curve for sarcopenia.

Results: The prevalence of sarcopenia diagnosed by L3-SMI was 29.9 % (102 / 341) and by AT-SMI was 35.5 % (121 / 341) in our cohort. The cut-off values of AT-SMI obtained by ROC curve were 12.6 cm2/m2 for female (AUC = 0.915, P < 0.001) and 14.2 cm2/m2 for male (AUC = 0.882, P < 0.001). Patient and graft survival rates in the sarcopenia group by AT-SMI were significantly lower than in the non-sarcopenia group (P < 0.001, P < 0.001). AT-SMI was identified as one of the independent prognostic factors in patient survival in multivariable cox analysis, whereas L3-SMI was not (HR, 4.462; 95 % CI, 1.792 – 11.106; P = 0.001). It was also confirmed by ROC curve analysis that AT-SMI was more highly correlated than L3-SMI for patient survival (P = 0.005).

Conclusion: Both the L3-SMI and AT-SMI-induced sarcopenia group had a significantly lower patient and graft survival than the group without sarcopenia. However, AT-SMI was identified as an independent prognostic factor for patient survival and was more correlated with patient survival than L3-SMI. This means that AT-SMI may be a better option than L3-SMI for the evaluation of CT-based sarcopenia in LT recipients.