Modified Model for End-Stage Liver Disease eXcluding INR (MELD-XI) Score Predicts Early Death After Pediatric Heart Transplantation

Abstract

We sought to determine the ability of the Model for End-Stage Liver Disease eXcluding INR (MELD-XI) to predict short-term and long-term outcomes in pediatric patients undergoing orthotopic heart transplant. The United Network for Organ Sharing Database was queried for all pediatric patients (aged 1 to 18 years) undergoing orthotopic heart transplant from 2000 to 2012. The logarithmic relationship between the serum creatinine and bilirubin was used to calculate the MELD-XI score. Lowess smoothing plots were referenced, and a score threshold of 12.2 was used to stratify patients into low (75%) and high (25%) MELD-XI cohorts. Patient-specific characteristics, intraoperative variables, and postoperative outcomes were compared between the two cohorts. Differences in survival at 30 days, 1 year, and 5 years between the MELD-XI cohorts were estimated by the Kaplan-Meier method. Cox proportional hazards modeling was used to determine the risk-adjusted effect of a high MELD-XI score on death. After patients with missing MELD-XI scores were excluded, 2,939 patients met the inclusion criteria. Unconditional 30-day (93.1% vs 98.0%, p < 0.001), 1-year (85.9% vs 92.9%, p < 0.001), and 5-year (71.2% vs 79.5%, p < 0.001) survivals were significantly worse in the high-score cohort. However, 1-year survival excluding 90-day deaths (94.9% vs 95.8%, p= 0.29) and 5-year survival excluding 1-year deaths (82.8% vs 85.6%, p= 0.09) were statistically equivalent. When modeled as a categoric variable, a high MELD-XI score was an independent predictor of death at 30 days (hazard ratio, 2.86; 95% confidence interval, 1.84 to 4.45; p < 0.001), 1 year (hazard ratio, 1.88; 95% confidence interval, 1.42 to 2.48, p < 0.001), and 5 years (hazard ratio, 1.41; 95% confidence interval, 1.19 to 1.77; p < 0.001). For every 1-point increase in the MELD-XI score, mortality increased 11% at 30 days, 7% at 1 year, and 4% at 5 years (p < 0.001). The MELD-XI was not predictive of conditional mortality at 1 year or 5 years. The MELD-XI scoring system can be used in pediatric orthotopic heart transplant to identify patients at risk for poor outcomes. Because long-term survival is largely driven by early death, renal insufficiency and congestive hepatopathy should be optimized before transplant.