An updated estimate of posttransplant survival after implementation of the new donor heart allocation policy

Abstract

The Organ Procurement and Transplant Network (OPTN) implemented a new heart allocation policy on October 18, 2018. Published estimates of lower posttransplant survival under the new policy in cohorts with limited follow-up may be biased by informative censoring. Using the Scientific Registry of Transplant Recipients, we used the Kaplan-Meier method to estimate 1-year posttransplant survival for pre-policy (November 1, 2016, to October 31, 2017) and post-policy cohorts (November 1, 2018, to October 31, 2019) with follow-up through March 2, 2021. We adjusted for changes in recipient population over time with a multivariable Cox proportional hazards model. To demonstrate the effect of inadequate follow-up on post-policy survival estimates, we repeated the analysis but only included follow-up through October 31, 2019. Transplant programs transplanted 2594 patients in the pre-policy cohort and 2761 patients in the post-policy cohort. With follow-up through March 2, 2021, unadjusted 1-year posttransplant survival was 90.6% (89.5%-91.8%) in the pre-policy cohort and 90.8% (89.7%-91.9%) in the post-policy cohort (adjusted HR = 0.93 [0.77-1.12]). Ignoring follow-up after October 31, 2019, the post-policy estimate was biased downward (1-year: 82.2%). When estimated with adequate follow-up, 1-year posttransplant survival under the new heart allocation policy was not significantly different.

Keywords: Organ Procurement and Transplantation Network (OPTN); Scientific Registry for Transplant Recipients (SRTR); health services and outcomes research; heart transplantation/cardiology; patient survival; registry/registry analysis; statistics.

Figure 1:. Survival of heart transplant recipients before and after implementation of the new heart allocation policy

1-year post-transplant survival was not significantly different since implementation of the new heart allocation policy. Shaded regions indicate 95% confidence intervals.

Figure 2:. Survival of heart transplant recipients before and after implementation of the new heart allocation policy with increasing follow-up

Estimates of 1-year post-transplant survival were biased downward by informative censoring with artificially truncated follow-up. However, the hazard ratio of transplant after policy implementation from an unadjusted Cox proportional hazards model was not significantly increased with truncated follow-up. Follow-up was truncated at November 1, 2019 (Panel A, log-rank P = 0.7, unadjusted HR = 1.04 [0.85–1.28]), May 1, 2020 (Panel B, log-rank P = 0.6, unadjusted HR = 1.04 [0.87–1.25]), and November 1, 2020 (Panel C, log-rank P = 0.9, unadjusted HR = 0.99 [0.83–1.18]). Panel D shows survival curves with full follow-up through March 2, 2021 (log-rank P = 0.8, unadjusted HR = 0.98 [0.82–1.17]).

Figure 3. Survival of heart transplant recipients before and after implementation of the new heart allocation policy by treatment type

Recipients who were treated with ECMO before transplant (Panel A) experienced significantly increased 1-year survival in the post-policy cohort (69.3% [59.6%–80.6%] pre-policy vs. 87.2% [81.8%–93.0%] post-policy, log-rank P < 0.001). Recipients who were treated with IABP before transplant (Panel B) showed no significant difference in 1-year survival (92.1% [90.0%–94.3%] pre-policy vs. 91.1% [89.1%–93.2%] post-policy, log-rank P = 0.6). Recipients who were treated with mechanical ventilation before transplant (Panel C) experienced significantly increased 1-year survival in the post-policy cohort (68.2% [57.8%–80.4%] pre-policy vs. 82.9% [74.5%–92.2%] post-policy, log-rank P = 0.03). Recipients who were treated with durable LVAD before transplant (Panel D) showed no significant difference in 1-year survival (91.5% [90.6%–92.4%] pre-policy vs. 90.4% [88.5%–92.4%] post-policy, log-rank P = 0.3).