Re-weighting the Model for End-Stage Liver Disease Score Components

Background & Aims

Liver transplant candidates with mild hepatic synthetic dysfunction and marked renal insufficiency may have higher Model for End-Stage Liver Disease (MELD) scores than candidates with severe liver disease and normal renal function. We re-estimated MELD coefficients and evaluated the effect of updated MELD on the liver transplant waiting list ranking.

Methods

Scientific Registry of Transplant Recipients data was analyzed for 38,899 adults wait-listed between September, 2001 and December, 2006. A time-dependent Cox regression waiting list mortality model estimated updated MELD component coefficients. Rank correlation between existing and updated MELD scores was computed.

Results

Existing MELD component coefficient (log_e creatinine, 0.957 vs 1.266 [95% confidence interval (CI), 1.21–1.32]; log_e bilirubin, 0.378 vs 0.939 [95% CI, 0.91–0.97]; log_e international normalized ratio, 1.120 vs 1.658 [95% CI, 1.58–1.74]) was significantly different than updated counterpart. Index of concordance was higher for updated MELD than existing MELD for predicting overall (0.68 vs. 0.64) and 90-day waiting list mortality (0.77 vs. 0.75). Rank correlation between existing and updated MELD scores was 0.95 for all candidates and 0.72 for candidates with existing MELD ≥20. Among candidates with equal existing MELD, those with lower creatinine and higher bilirubin had significantly higher waiting list mortality.

Conclusions

Existing MELD coefficient components are significantly different than those calculated from national waiting list data. Updated MELD assigns lower weight to creatinine and international normalized ratio and higher weight to bilirubin. Updated MELD better predicts waiting list mortality. Using updated MELD for liver allocation would alter waiting list candidate ranking.

Abbreviations used in this paper: IOC, Index of concordance, MELD, Model for End-Stage Liver Disease, RRT, renal replacement therapy