New kidney-after-heart allocation policy in the United States: Who would benefit from a rescue kidney?

Abstract

Background

The new rescue kidney policy in the United States was implemented in June 2023. To estimate its potential impact, we investigated a historic cohort of heart transplant (HT) recipients who would have been eligible for a kidney-after-heart transplant under this policy.

Methods

Adult heart-only recipients from January 1, 2000 to March 31, 2023 in the United Network for Organ Sharing database were categorized by retroactively applying eligibility criteria from the new policy: estimated glomerular filtration rate (eGFR) ≤ 20 ml/min, creatinine clearance (CrCl) ≤ 20 ml/min, or dialysis 60–365 days post-HT. We evaluated outcomes of eligible recipients.

Results

Of 45,833 HT recipients, 840 (1.8%) were eligible for a rescue kidney. Eligible recipients had higher median age (58 vs 56 years, p < 0.001) and serum creatinine (1.4 vs 1.2, p < 0.001), and were more likely to be status 1A in the pre-2018 allocation era (63.4% vs 51.9%, p < 0.001) and status 1 in the post-2018 allocation era (13.9% vs 9.1%, p = 0.003). Survival at 1 year conditional on 60-day survival was worse for eligible recipients (50.8% vs 96.3%; HR 17.6 [95% CI: 15.8–19.6], p < 0.001). Post-HT, 607 (72.3%) eligible recipients were never listed for kidney transplant (KT), of whom 486 (80.1%) died with a median time-to-death of 8.8 months. Among the 233 (27.7%) recipients listed for KT, 65 (27.9%) died/deteriorated on the waitlist and 99 (42.5%) received a KT (median 38.4 months post-HT).

Conclusions

Half of recipients eligible for a rescue kidney did not survive to 1 year post-HT, and >70% were never listed for KT. The effects of the new policy on mitigating mortality in this challenging population will be paramount.