Consideration of donor age and human leukocyte antigen matching in the setting of multiple potential living kidney donors

Background: Defining living donor (LD)-related risk factors affecting kidney transplant outcome will allow better donor selection and more educated informed consent when there is more than one potential donor. We studied risk factors in a large cohort at a single institution. Methods: We reviewed 1632 recipients who underwent LD kidney transplantation at the University of Minnesota between January 1, 1990, and October 1, 2009. Using Cox regression, we studied the effect of donor and recipient risk factors on patient and graft survival. We specifically examined the effect of donor age and human leukocyte antigen (HLA) matching because these are variables that may help clinical decision making when multiple potential donors exist. Results: Mean donor age was 40.6 years for all transplants; 180 (11%) donors were 55 years or older, and 24 (1.5%) donors were older than 65 years. Mean number of HLA mismatches (per transplant) was 2.9 (29.2% of recipients had one to two HLA mismatches, 39.8% had three to four HLA mismatches, and 25% had five to six HLA mismatches). Donor age more than 65 years, five to six HLA mismatches, delayed graft function, and acute rejection were independent predictors of decreased patient and graft survival. When controlling for recipient age, donor age more than 65 years remained a risk factor for worse outcome. Conclusions: Our data suggest that advanced donor age (>65 years) and degree of HLA mismatch (5) are independent donor-related risk factors associated with worse outcome. When multiple potential LDs exist, it may be ideal to attempt to use a donor younger than 65 years and with less than five HLA mismatches.