Clinical Scorecard: Mortality score may refine heart allocation

At a Glance

Key Highlights

• In the test data set, the simpler US-CRS 2.0 model had a mean area under the receiver operating characteristic curve of 0.807 for 6-week mortality, compared with 0.693 for the existing 6-status system.
• Both proposed allocation approaches placed candidates with higher observed short-term mortality risk at the top of historical donor match runs.
• The score differentiated risk by mechanical circulatory support category; durable left ventricular assist device use was associated with lower short-term mortality, while other evaluated support categories were associated with higher mortality.
• Proposed approaches changed candidate rankings and prioritized more candidates from racial and ethnic minority groups, while reducing priority for candidates with blood type O and those using durable left ventricular assist devices.
• The models overestimated mortality among candidates at the highest predicted risk, and the authors noted that recalibration and further simulation would be needed before implementation.

Guideline-Based Recommendations

Diagnosis

• The study evaluated prediction of mortality within 6 weeks without transplantation, defined as death before transplantation or removal from the waiting list because of clinical deterioration.
• US-CRS 2.0 incorporates 5 laboratory measurements and 4 categories of mechanical circulatory support.

Management

• The investigators simulated replacing existing adult urgency statuses with US-CRS-derived categories and, separately, ranking adult candidates nationally by a 50-point US-CRS score.
• The authors stated that a full simulation incorporating relevant allocation considerations would be necessary before implementation.

Monitoring & Follow-up

• The authors noted that the score would require periodic recalibration as transplant practices and heart failure management evolve.
• The models were well calibrated across urgency statuses, exception categories, and diagnoses overall, but overestimated mortality among candidates at the highest predicted risk.

Risks

• The match-run analysis could not quantify potential effects on post-transplant survival if donor hearts were allocated to candidates with greater medical urgency.
• Both proposed approaches reduced priority for candidates with blood type O and those using durable left ventricular assist devices; the authors noted the need for separate allocation provisions to maintain equitable access.
• The study identified variation in predicted mortality among candidates assigned the same existing urgency status, including candidates with exception statuses.

Patient & Prescribing Data

The analysis included 33,097 adult heart transplant candidates listed between January 2019 and August 2025; some patients contributed data to more than one data set.

This was an allocation-risk modeling study, not a treatment trial. In the evaluated score, durable left ventricular assist device use was associated with lower short-term mortality, while intra-aortic balloon pumps, microaxial flow pumps, and advanced mechanical circulatory support were associated with higher mortality.

Clinical Best Practices

• Interpret US-CRS 2.0 as a proposed risk and allocation tool; the article does not report its implementation as current policy.
• Account for the study's observed overestimation of mortality among candidates at the highest predicted risk.
• Consider the reported changes in priority by blood type and durable left ventricular assist device use when evaluating proposed allocation approaches.
• The authors called for full simulation and periodic recalibration before implementation.

Related Resources & Content

• JAMA study (study details and author disclosures referenced in the article)