Optimization of heart allocation: The transplant risk score

Abstract

The new French heart allocation system is designed to minimize waitlist mortality and extend the donor pool without a detrimental effect on posttransplant survival. This study was designed to construct a 1‐year posttransplant graft‐loss risk score incorporating recipient and donor characteristics. The study included all adult first single‐organ recipients transplanted between 2010 and 2014 (N = 1776). This population was randomly divided in a 2:1 ratio into derivation and validation cohorts. The association of variables with 1‐year graft loss was determined with a mixed Cox model with center as random effect. The predictors were used to generate a transplant‐risk score (TRS). Donor‐recipient matching was assessed using 2 separate recipient‐ and donor‐risk scores. Factors associated with 1‐year graft loss were recipient age >50 years, valvular cardiomyopathy and congenital heart disease, previous cardiac surgery, diabetes, mechanical ventilation, glomerular filtration rate and bilirubin, donor age >55 years, and donor sex: female. The C‐index of the final model was 0.70. Correlation between observed and predicted graft loss rate was excellent for the overall cohort (r = 0.90). Hearts from high‐risk donors transplanted to low‐risk recipients had similar survival as those from low‐risk donors. The TRS provides an accurate prediction of 1‐year graft‐loss risk and allows optimal donor‐recipient matching.

Risk prediction models for survival after heart transplantation: A systematic review

“…Of the 71 articles, 21 studies were included in the systematic review (Figure ). There were 16 scores identified: five were not validated, four were internally validated, and seven were validated in external cohorts . Table describes scores validated in external cohorts and Table describes scores that were not validated or only internally validated.…”

“…The model performed poorly with UNOS data from 1985 to 2015 with AUROC of 0.556 and from 2009 to 2011 with a C‐statistic of 0.58 for 1‐year survival . The IMPACT score was also validated on contemporary data from the French national transplant database and was found to have poor discrimination and model calibration (Table ) …”

“…A 1‐point increase predicted an 8.3% increase in the odds of 1‐year mortality (odds ratio: 1.08, 95% confidence interval [CI] 1.06‐1.11) in the internal validation cohort. The model did not perform well in an external cohort from the French national transplant database (observed vs predicted 1‐year mortality or retransplantation, r = .50) and C‐statistic 0.60 …”

“…The TRS was derived from 1776 transplants from 2010‐2014 in the French national database . The TRS is a 30‐point score composed of seven recipient and two donor predictors that also took into account between‐center variability in its model development.…”

“…There were 16 scores identified: five were not validated, [19][20][21][22] four were internally validated, [23][24][25][26] and seven were validated in external cohorts. [17][18][19][21][22][23][24][25][26][27][28][29] Table 1 describes scores validated in external cohorts and Table 2 describes scores that were not validated or only internally validated. There were 28 donor and 48 recipient variables identified in the 16 scores ( Figure 2).…”