Meta-analysis of cohort trials comparing the effect of different mismatches of human leukocyte antigen epitopes on graft survival and acute rejection. A: 0-2 vs 3-6 mismatches of human leukocyte antigen (HLA)-A, B, DR epitopes on 1-year graft survival; B: 0-2 vs 3-6 mismatches of HLA-A, B, DR epitopes on 5-year graft survival; C: 0 vs 1-2 mismatches of HLA-A epitopes on 1-year graft survival; D: 0 vs 1-2 mismatches of HLA-A epitopes on 5-year graft survival; E: 0 vs 1-2 mismatches of HLA-B epitopes on 1-year graft survival; F: 0 vs 1-2 mismatches of HLA-DR epitopes on 1-year graft survival; G: 0 vs 1-2 mismatches of HLA-DR epitopes on 5-year graft survival; H: 0-2 vs 3-6 mismatches of HLA-A, B and DR epitopes on acute rejection.