Abstract: No studies reported on NMP, however one ongoing study was identified. Sixteen studies (2266 participants) comparing HMP with SCS were included; 15 studies could be meta-analysed. Fourteen studies reported on requirement for dialysis in the first week post-transplant (DGF incidence); there is high-certainty evidence that HMP reduces the risk of DGF when compared to SCS (RR 0.77; 95% CI 0.67 to 0.90; P = 0.0006). HMP reduces the risk of DGF in kidneys from DCD donors (7 studies, 772 participants: RR 0.75; 95% CI 0.64 to 0.87; P = 0.0002; high certainty evidence), as well as kidneys from DBD donors (4 studies, 971 participants: RR 0.78, 95% CI 0.65 to 0.93; P = 0.006; high certainty evidence). The number of perfusions required to prevent one episode of DGF (number needed to treat, NNT) was 7.26 and 13.60 in DCD and DBD kidneys respectively. Studies performed in the last decade all used the LifePort machine and confirmed that HMP reduces the incidence of DGF in the modern era (5 studies, 1355 participants: RR 0.77, 95% CI 0.66 to 0.91; P = 0.002; high certainty evidence). Reports of economic analysis suggest that HMP can lead to cost savings in both the North American and European settings. Two studies reported HMP also improves graft survival however we were not able to meta-analyse these results. A reduction in incidence of PNF could not be demonstrated. The effect of HMP on our other outcomes (incidence of acute rejection, patient survival, hospital stay, long-term graft function, duration of DGF) remains uncertain. HMP is superior to SCS in deceased donor kidney transplantation. This is true for both DBD and DCD kidneys, and remains true in the modern era (studies performed in the last decade). As kidneys from DCD donors have a higher overall DGF rate, fewer perfusions are needed to prevent one episode of DGF (7.26 versus 13.60 in DBD kidneys). Further studies looking solely at the impact of HMP on DGF incidence are not required. Follow-up reports detailing long-term graft survival from participants of the studies already included in this review would be an efficient way to generate further long-term graft survival data. Economic analysis, based on the results of this review, would help cement HMP as the standard preservation method in deceased donor kidney transplantation. RCTs investigating (sub)NMP are required.

Plain-language summary: Sixteen studies (2266 participants) comparing hypothermic machine perfusion with static cold storage were included. The use of hypothermic machine perfusion instead of standard static cold storage reduces the risk of DGF by approximately 23%. Two reports performed economic analysis, in the USA and European settings, and both estimated cost savings with the use of hypothermic machine perfusion. Two studies reported hypothermic machine perfusion prolongs the length of time that donated kidneys survive in the recipient, however we were unable to perform an analysis to confirm this. The effect of HMP on other outcomes (incidence of acute rejection, patient survival, hospital stay, long-term kidney function, duration of DGF) remains uncertain. No completed studies investigating normothermic machine perfusion were identified, but one ongoing study was identified. Compared with standard static cold storage, hypothermic machine perfusion reduces the rate of DGF in kidneys from deceased donors, and likely results in increased survival of the transplanted kidney and overall cost savings. Studies looking at normothermic machine perfusion are required to assess if this results in superior outcomes.