From Patients to Providers: Assessing the Impact of Normothermic Machine Perfusion on Liver Transplant Practices in the US

Abstract

BACKGROUND: Normothermic machine perfusion (NMP) of livers allows for the expansion of the donor pool and minimization of post-transplant complications. Results to date have focused on both donor and recipient outcomes, but there remains potential for NMP to also impact transplant providers. STUDY DESIGN: Using UNOS STARfile data, adult deceased donors transplanted between 1/1/2016-12/31/2022 were identified. Transplanted livers were divided by preservation method (static cold storage (SCS); NMP) and case time (day-reperfusion 8am-to-6pm). Patient factors, transplant characteristics, and short-term outcomes were analyzed between Mahalanobis-metric-matched groups. RESULTS: NMP livers represented 742 (1.4%) of 52,132 transplants. NMP donors were more marginal with higher DRI scores (1.78 ± 0.50 NMP vs 1.49 ± 0.38 SCS, P<0.001) and DCD frequency (36.9% vs 8.4%, P<0.001). NMP recipients more often had MELD exception status (29.9% vs 23.4%, P<0.001), lower lab MELD scores (20.7 ± 9.7 vs 24.3 ± 10.9, P<0.001), and had been waitlisted longer (111.5 [21.0-307.0] vs 60.0 [9.0-245.0] days, P<0.001). 1-year graft survival (90.2% vs 91.6%, P=0.505) was similar between groups, while length-of-stay was lower for NMP recipients (8.0 [6.0-14.0] vs 10.0 [6.0-16.0], P=0.017) after adjusting for confounders. Notably, peak case volume occurred at 11 am with NMP livers (vs. 9 pm with SCS). Overall, a higher proportion of transplants were performed during daytime hours with NMP (51.5% vs 43.0%, P<0.001). CONCLUSION: NMP results in increased use of marginal allografts, which facilitated transplantation of lower lab MELD recipients who have been waitlisted longer and often have exception points. Importantly, NMP also appeared to shift peak caseloads from nighttime to daytime, which may have significant effects on the quality of life for the entire liver transplant team.