Single versus Double Umbilical Cord Blood Transplants: A Meta-analysis of Comparative Studies Umbilical Cord Blood Transplants

Background: A number of alternatives has been proposed, including umbilical cord blood transplant (UCBT),in patients who do not matched donors for hematopoietic stem cell transplantation (HSCT). However, thereare conflicting results regarding the role of the two units UCBT (dUCBT) compared to single unit (sUCBT).The present systematic review and meta-analysis aimed to compare the outcomes of dUCBT versus sUCBTin patients without suitable HLA-matched donorMaterial and Methods: We performed an electronic search in the following bibliographic databases: Medlinevia PubMed, SCOPUS, Web of Science, and Cochrane Central Register of Controlled Trials (CENTRAL).Both prospective and retrospective studies which compared sUBCT and dUBCT were included. Data wereanalysed using RevMan version 5.3 for windows.Results: The present review included 12eligible studies. The overall effect estimates did not favour eitherof the two groups in terms of neutrophil engraftment (OR =0.92, 95% CI [0.71, 1.19]; p =0.52), palatalsengraftment (OR = 1.10, 95% CI [0.79, 1.53]; p =0.59), relapse rates (OR = 1.31, 95% CI [0.82, 2.09]; p=0.26) 5-year disease-free survival (OR = 0.87, 95% CI [0.59, 1.28]; p =0.49), and 5-year overall survival(OR Figure.6). However, the overall effect estimates favoured sUCBT group over the dUCBT group in termof the incidence of grade 2-4 GVHD (OR = 0.66, 95% CI [0.45, 0.97]; p =0.03).Conclusion: In conclusion both sUCBT and dUCBT have comparable results in terms of engraftmentsuccess, relapse rates, transplant-related mortality, and overall survival. However, dUCBT is associated withhigher risk of acute GVHD which further limit any potential advantages of the dUCBT.