ISHLT Annual Meeting Papers
Association of high-priority exceptions with waitlist mortality among heart transplant candidates

https://doi.org/10.1016/j.healun.2023.05.009Get rights and content

Background

The US heart allocation system ranks candidates using six categorical status levels. Transplant programs can request exceptions to increase a candidate’s status level if they believe their candidate has the same medical urgency as candidates who meet the standard criteria for that level. We aimed to determine if exception candidates have the same medical urgency as standard candidates.

Methods

Using the Scientific Registry of Transplant Recipients, we constructed a longitudinal waitlist history dataset of adult heart-only transplant candidates listed between October 18, 2018 and December 1, 2021. We estimated the association between exceptions and waitlist mortality with a mixed-effects Cox proportional hazards model that treated status and exceptions as time-dependent covariates.

Results

Out of 12,458 candidates listed during the study period, 2273 (18.2%) received an exception at listing and 1957 (15.7%) received an exception after listing. After controlling for status, exception candidates had approximately half the risk of waitlist mortality as standard candidates (hazard ratio [HR] 0.55, 95% confidence interval [CI] [0.41, 0.73], p < .001). Exceptions were associated with a 51% lower risk of waitlist mortality among Status 1 candidates (HR 0.49, 95% CI [0.27, 0.91], p = .023) and a 61% lower risk among Status 2 candidates (HR 0.39, 95% CI [0.24, 0.62], p < .001).

Conclusions

Under the new heart allocation policy, exception candidates had significantly lower waitlist mortality than standard candidates, including exceptions for the highest priority statuses. These results suggest that candidates with exceptions, on average, have a lower level of medical urgency than candidates who meet standard criteria.

Section snippets

Data source and study population

This study used data from the Scientific Registry of Transplant Recipients (SRTR). The SRTR data system includes data on all donor, waitlisted candidates, and transplant recipients in the US, submitted by the members of the OPTN. The Health Resources and Services Administration, US Department of Health and Human Services provides oversight to the activities of the OPTN and SRTR contractors. This study was a secondary analysis of deidentified data and was granted exemption status by the

Overall study population characteristics by exception

A total of 12,776 active adult heart transplant candidates were added to the transplant waitlist between October 18, 2018, and December 1, 2021 (Figure S1). Among this sample, 318 candidates were excluded for listing as permanently inactive (n = 59), listing at a low-volume center (n = 62), or listing using the previous allocation system (n = 197). The final sample included 12,458 candidates listed at 112 transplant centers, including 2273 candidates (18.2%) who received an exception at initial

Discussion

In this longitudinal study of the waitlist history of 12,458 heart transplant candidates, we found that 30% and 40% of candidates listed at Statuses 1 and 2 received exceptions, respectively, and the proportion of exception candidates at each status remained approximately the same over time. Adjusted for status, candidates listed for high-priority heart transplant statuses with an exception had a 45% lower risk of dying on the waitlist than candidates meeting standard criteria. This association

Conclusion

Adult heart transplant candidates granted exceptions under the new heart allocation policy were significantly less likely to die on the waitlist than candidates who met the standard criteria. A substantial proportion of candidates received high-priority Status 1 and 2 designations through exceptions, counteracting the efforts of the new heart allocation policy to reduce the number of exceptions. Further work is needed to ensure equitable allocation of donor hearts while simultaneously reducing

Author Contributions

Johnson and Parker developed the study design, performed all data analyses, and drafted the manuscript. Ahn, Lazenby, Zeng, and Zhang contributed to data analysis. All co-authors interpreted data and revised the manuscript for important intellectual content.

Disclosure statement

W.F. Parker was funded by National Institutes of Health grant K08HL150291, K.K. Khush was funded by National Institutes of Health grant R01HL125303 and D.Y. Johnson was funded by National Institutes of Health National Heart, Lung, and Blood Institute grant #5R25HL096383-12. All other authors have nothing to disclose.

Acknowledgments

The data reported here have been supplied by the Hennepin Healthcare Research Institute (HHRI) as the contractor for the Scientific Registry of Transplant Recipients (SRTR). The interpretation and reporting of these data are the responsibility of the authors and in no way should be seen as an official policy of or interpretation by the SRTR or the U.S. Government.

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