Impact of human leukocyte antigen mismatching on outcomes of liver transplantation:A meta-analysis

AIM:To assess the effect of human leukocyte antigen(HLA) mismatching on liver graft outcome and acute rejection from a meta-analysis of available cohort studies.METHODS:Articles in PubMed/MEDLINE,EMBASE and the Cochrane database from January 1970 to June 2009,including non-English literature identified in these databases,were searched.Only studies comparing HLA or sub-phenotype matching with mismatching were extracted.The percentage of graft survival was extracted by "Engauge Digitizer" from survival curves if the raw data were not displayed.A meta-analysis was performed when at least 3 studies provided data.RESULTS:Sixteen studies met the inclusion criteria.A lower number of HLA mismatches(0-2 vs 3-6) did reduce the incidence of acute rejection(relative risk:0.77,P = 0.03).The degree of HLA mismatching(0-2 vs 3-6) had no significant effect on 1-year [hazard ratio(HR):1.04,P = 0.68] and 5-year(HR:1.09,P = 0.38) graft survival.In sub-phenotype analysis,the degree of HLA-A,B and DR mismatching(0 vs 1-2) had no significant effect on 1-year and 5-year graft survival,either.The HRs and P-values were 0.95,0.71(HLA-A,1-year);1.06,0.60(HLA-A,5-year);0.77,0.16(HLA-B,1-year);1.07,0.56(HLA-DR,1-year);1.18,0.23(HLADR,5-year),respectively.CONCLUSION:The results of this systematic review imply that good HLA compatibility can reduce the incidence of acute rejection in spite of having no influence on graft outcomes.To obtain a short recovery time and minimize rejection post transplantation,HLA matching studies should be considered before the operation.