HLA-DR matching in organ allocation: balance between waiting time and rejection in pediatric kidney transplantation.

Objectives: To determine the impact of HLA-DR mismatching on rejection, graft survival, and sensitization in a local allocation system that emphasizes donor quality rather than HLA antigen matching for pediatric patients and to determine the likelihood of finding an appropriate donor based on HLA-DR mismatch.

Design: Retrospective cohort study.

Setting: A single institution.

Patients: A total of 178 patients younger than 21 years who underwent kidney transplantation with daclizumab induction between 1997 and 2006.

Main Outcome Measures: The association between HLA-DR mismatching and rejection or graft survival was determined using survival analysis. Sensitization was defined as a posttransplantation panel reactive antibody level greater than 0% in patients with a pretransplantation level of 0%.

Results: Median follow-up was 4.1 years (interquartile range, 2.1-6.1 years). One- and 5-year graft survival rates were 97% and 82%, respectively. HLA-DRB1 mismatches were a significant risk factor for rejection; patients with 1- or 2-HLA-DRB1 mismatches had 1.7 times greater odds of rejection than those with 0-HLA-DR mismatches (P = .006). HLA-DRB1 mismatching was not a significant risk factor for either graft failure or sensitization, but history of rejection was an independent predictor of graft failure (hazard ratio, 7.7; P = .01) and sensitization (odds ratio, 9.7; P = .001). Although avoiding HLA-DRB1 mismatching reduces rejection, the probability of finding ABO-matched local donors younger than 35 years without DR mismatches was extremely low.

Conclusion: Although avoiding HLA-DRB1 mismatching is beneficial, the likelihood of finding an HLA-DRB1-matched donor should also be considered in donor selection.