Predictive value of controlled attenuation parameter in living liver donors for graft outcomes in corresponding recipients

The controlled attenuation parameter (CAP), derived from ultrasound-based transient elastography, is a useful tool for noninvasive assessment of hepatic steatosis. However, its prognostic significance for graft outcomes in living donor liver transplantation (LDLT) has not been examined. This study aimed to investigate the predictive value of CAP measurements in estimating the risk of graft failure in LDLT recipients. We retrospectively analyzed 146 adult-to-adult LDLT procedures performed at our transplant center between January 2014 and June 2024. Graft survival was assessed using multivariate Cox regression models stratified by graft-to-recipient weight ratio (GRWR), using 0.8% as the standard cutoff. There was a positive correlation between CAP values and histological grades of graft steatosis. Among recipients with GRWR ≥0.8% (n=66), CAP was not significantly associated with graft survival. In contrast, among recipients with GRWR <0.8% (n=80), higher CAP values were independently associated with worse graft survival ( p =0.04), along with donor age ( p =0.02). Among recipients with GRWR <0.8%, the median CAP values in those who developed grade A or B small-for-size syndrome (SFSS) were significantly higher than those who did not develop SFSS ( p =0.04 and p =0.03, respectively). Furthermore, graft survival outcomes were significantly differentiated by CAP value, even within histological grade 0 donor livers. In conclusion, higher CAP values were associated with increased risk of SFSS and graft failure in LDLT recipients with GRWR <0.8%. Incorporating CAP into graft selection and pretransplant risk assessment may improve recipient outcomes, particularly when using small grafts in LDLT.