Thigh muscle index as a valuable prognostic marker in middle-aged male patients undergoing liver transplantation.

In liver transplantation (LT), determining the optimal recipients is crucial, and the MELD score has been used for this purpose. However, the MELD score does not reflect functional status, leading to the evaluation of sarcopenia. While the L3 skeletal muscle index (SMIL3) is commonly used for assessment, the upper thigh skeletal muscle index (SMIUT) may better represent functional capacity. This retrospective study included 246 male LT recipients aged 40-60 from 2013 to 2015. Preoperative and postoperative muscle and fat areas at the L3 and upper thigh levels were quantified using artificial intelligence software. Clinical outcomes, including ventilator, ICU, and hospital days, were analyzed using logistic regression, while survival was evaluated using Cox regression and Kaplan-Meier curves. Longitudinal body composition changes were assessed over 5 years post-LT. SMIUT demonstrated stronger associations with hospital days (R²=0.378) than SMIL3 (R²=0.302). High SMIUT correlated with improved survival (P=0.02), unlike SMIL3. Longitudinal analysis revealed a significant divergence in SMIUT between survivors and non-survivors, whereas SMIL3 showed no significant changes. The visceral fat index at L3 (VFIL3) increased continuously, highlighting potential metabolic risks. SMIUT showed a similar or even stronger association with LT outcomes than SMIL3, effectively reflecting patient prognosis. SMIUT in the postoperative period also better reflected clinical status. Therefore, pre- and postoperative SMIUT is helpful for patient assessment and ongoing management in LT patients.