Development of a risk score model for 1‐year graft loss after adult deceased donor liver transplantation in Japan based on a 20‐year nationwide cohort

AIM: Using nationwide data collected over the past 20 years, we aimed to investigate deceased donor liver transplantation (DDLT) outcomes to develop a unique risk model that can be used to establish a standard for organ acceptance in Japan. METHODS: Data were collected for 449 recipients aged ≥18 years who underwent DDLT between 1999 and 2019. Least absolute shrinkage and selection operator (LASSO) regression analysis was utilized to develop an original risk score model for 1‐year graft loss (termed the Japan Risk Index [JRI]). We developed risk indices according to recipient, donor, and surgery components (termed JRI‐R, D, and S, respectively). The JRI was validated via a 5‐fold cross‐validation. We also compared DDLT outcomes and risk indices among Era1 (−2011), Era2 (−2015), and Era3 (−2019). RESULTS: The 1‐year graft survival rate was 89.5% and improved significantly, reaching 84.7%, 87.6%, and 93.9% in Era1, Era2, and Era3, respectively. The JRI was calculated as JRI‐R (re‐transplantation, Model for End‐Stage Liver Disease score, medical condition in intensive care unit) × JRI‐D (age, catecholamine index, maximum sodium, maximum total bilirubin) × JRI‐S (total ischemic time) × 0.84. The risk model achieved a mean C‐statistic value of 0.81 in the validation analysis. The risk index was significantly lower in Era3 than in Era2. CONCLUSION: Changes in the risk index over time indicated that avoiding risks contributed to the improved outcomes in Era3. The JRI is unique to adult DDLT in Japan and may be useful as a reference for organ acceptance in the future.