US-CRS Score Could Prioritize Sicker Heart Transplant Candidates

A medical urgency score based on laboratory values and therapeutic devices discriminated 6-week waitlist mortality better than the current US 6-status heart allocation system and, in simulated match runs, prioritized sicker candidates without increasing donor-candidate distance, according to a registry-based study published in JAMA.

The investigators noted that 1 in 5 US heart transplant candidates die or are delisted without transplant and that the current 6-status therapy-based system has been criticized for limited risk stratification and susceptibility to gaming. The study aimed to develop an allocation policy based on an objective medical urgency score that ranks candidates on the interaction between physiology and mechanical circulatory support.

The observational study used US organ transplant system data on all adult heart transplant candidates from January 2019 to August 2025, divided into consecutive training (n = 21,859), validation (n = 7,897), and test (n = 8,256) datasets (mean age, 53 years; 74% male). The resulting US Candidate Risk Score (US-CRS), a marginal structural model of 6-week mortality without transplant, included 5 laboratory values and 4 therapeutic devices: durable left ventricular assist device, intra-aortic balloon pump, microaxial flow pump, and advanced mechanical circulatory support. In the test set, the US-CRS had similar or significantly higher time-dependent area under the curve (AUC) than the 6-status system (mean AUC, 0.807 vs 0.693) and acceptable calibration by status, especially among candidates who received their status by exception.

In a match-run analysis of 45,530 donor hearts, a US-CRS–based system moved 67% of transplant recipients down in rank order. Observed 6-week transplant-censored mortality for the first candidate on the match run increased from 11.2% (95% CI, 10.1%-12.5%) under the current system to 15.7% (95% CI, 13.9%-17.6%) under the US-CRS–based system. The investigators reported that the reordering did not increase donor-candidate distance.

The authors concluded that the US-CRS–based system prioritized sicker candidates with higher mortality without transplant compared with current medical urgency statuses, and they wrote that integrating the score into adult heart allocation could reduce waitlist deaths without increasing the distance grafts travel. The findings come from observational registry data and a simulated reordering of match runs.

Source: Lyden GR, White M, Ahn DJ, et al. Development and validation of an adult medical urgency score for US donor heart allocation. JAMA. Published online October 12, 2026. doi:10.1001/jama.2026.17403