Variability in Status 1 Exception Practices and Candidate Outcomes After the 2018 US Heart Allocation Changes

Area of Science:

• Cardiology
• Transplantation Medicine
• Health Services Research

Background:

• Status 1 listings signify the highest priority for heart transplantation (HT), reserved for candidates with critical medical urgency, such as those requiring VA-ECMO.
• The 2018 allocation system change aimed to optimize organ distribution and improve outcomes for heart transplant candidates.

Purpose of the Study:

• To analyze longitudinal trends in Status 1 heart transplant listings post-2018.
• To evaluate variations in center-level listing practices, particularly the use of exceptions.
• To assess the impact of the allocation change on transplant outcomes, comparing candidates listed with and without exceptions.

Main Methods:

• Analysis of de-identified data from the Organ Procurement and Transplantation Network (OPTN) for adult, first-time, single-organ HT candidates listed as Status 1 between October 2018 and July 2024.
• Evaluation of trends in overall and exception (1E) listings by time, geographic region, and transplant center size.
• Application of Fine-Gray subdistribution hazards regression to compare 30-day transplant and delisting rates for death/deterioration based on exception status.

Main Results:

• Status 1 listings doubled from 7.1% to 14.4% between 2018 and 2024, primarily driven by a rise in 1E listings (2.3% to 9.8%), which constituted over 50% of Status 1 listings by 2024.
• Significant variation in the use of 1E listings was observed across different transplant centers and regions.
• Candidates listed as 1E demonstrated similar 30-day transplant rates but a lower risk of delisting due to death or deterioration compared to non-exception Status 1 candidates.

Conclusions:

• The utilization of Status 1 heart transplant listings has significantly increased post-2018, with a notable rise in the application of exception (1E) criteria, showing considerable inter-center variability.
• Candidates listed under the 1E status appear to have less severe pre-transplant conditions compared to traditional Status 1 patients.
• Patients with specific disadvantages, such as blood group O or high panel reactive antibodies (PRA ≥30%), continue to face elevated risks for adverse outcomes, including lower heart transplant rates and increased delisting for death/deterioration.