title: Systematic review and meta-analysis of hypothermic machine perfusion versus static cold storage of kidney allografts on transplant outcomes.
abstract: BACKGROUND
  Adequate preservation of renal allografts for transplantation is important for maintaining and improving transplant outcomes. There are two prevalent methods: hypothermic machine perfusion and static cold storage. The preferred method of storage, however, remains controversial. The objective was to review systematically the evidence comparing outcomes from these two modalities.
  
  
  METHODS
  A literature search was performed using MEDLINE, Embase, the Cochrane Library, the Transplant Library and the International Clinical Trials Registry Platform. The final date for searches was 30 November 2012. Studies were assessed for methodological quality. Summary effects were calculated as relative risk (RR) with 95 per cent confidence interval (c.i.). Randomized clinical trials (RCTs) and non-RCTs were included, but evaluated separately. Results from RCTs alone were used for meta-analysis.
  
  
  RESULTS
  Eighteen studies met the inclusion criteria, including seven RCTs (1475 kidneys) and 11 non-RCTs (728 kidneys). The overall risk of delayed graft function was lower with hypothermic machine perfusion than static cold storage (RR 0·81, 95 per cent c.i. 0·71 to 0·92; P = 0·002). There was no difference in the rate of primary non-function (RR 1·15, 0·46 to 2·90; P = 0·767). There was a faster initial fall in the level of serum creatinine with hypothermic machine perfusion in two RCTs, but not in another. There was no relationship between rates of acute rejection or patient survival and the method of preservation.
  
  
  CONCLUSIONS
  Data from the included studies suggest that hypothermic machine perfusion reduces delayed graft function compared with static cold storage. There was no difference in primary non-function, acute rejection, long-term renal function or patient survival. A difference in renal graft survival is uncertain.
authors.affiliation: Centre for Evidence in Transplantation, Royal College of Surgeons of England and London School of Hygiene and Tropical Medicine, University of London, London, UK. jocallaghan@rcseng.ac.uk
authors.forename: J M
authors.initials: JM
authors.lastname: O'Callaghan
authors.forename: R D
authors.initials: RD
authors.lastname: Morgan
authors.forename: S R
authors.initials: SR
authors.lastname: Knight
authors.forename: P J
authors.initials: PJ
authors.lastname: Morris
mesh_terms: D051799:Delayed Graft Function / Q000209:etiology*; D004867:Equipment Design; D006084:Graft Rejection / Q000209:etiology; D006085:Graft Survival / Q000502:physiology; D006801:Humans; D006979:Hyperthermia, Induced / Q000295:instrumentation / Q000379:methods*; D016030:Kidney Transplantation / Q000379:methods*; D009926:Organ Preservation / Q000379:methods*; D010477:Perfusion / Q000379:methods*; D016032:Randomized Controlled Trials as Topic; D014184:Transplantation, Homologous; D016896:Treatment Outcome