Development and Validation of an Adult Medical Urgency Score for US Donor Heart Allocation.

A new US heart allocation system based on the US-CRS predicts 6-week mortality with higher accuracy than the current 6-status system, with a mean AUC of 0.807 versus 0.693.

• Why it matters: Current heart donor allocation relies on a 6-status system that has been criticized for limited risk stratification and susceptibility to gaming, risking suboptimal prioritization of the sickest candidates.
• What they did: The study developed the US-CRS using data from 21,859 candidates in a registry-based observational design, incorporating five laboratory values and four therapeutic devices, and validated its predictive performance through model comparison and simulation.
• The result: Implementing the US-CRS in a match-run simulation caused 67% of transplant recipients to move down in rank and increased 6-week transplant-censored mortality from 11.2% to 15.7%, indicating prioritization of sicker candidates with higher mortality risk.