Enhanced significance of donor-recipient age gradient as a prognostic factor of graft outcome in living donor kidney transplantation

Background: Successful kidney transplantation (KT) increases survival and improves quality of life for patients with end-stage renal disease. Donor age is an important factor influencing graft outcomes. We evaluated the relationship between the donor-recipient age gradient (DRAG) and graft outcomes after living-donor kidney transplantation (LDKT). Additionally, we analyzed graft survival in patients receiving kidneys from age-mismatched donors. Methods: From February 1995 to March 2011, a series of 968 consecutive adult LDKT recipients were enrolled in our study. Graft survival and laboratory data for each patient were retrospectively collected. DRAG values were divided into four groups: ≤-21, -20 to -1, 0-20, and ≥21 years. Results: Higher DRAG had negative effects on graft rejection episodes and serum creatinine levels beyond the first month post-transplantation. A DRAG of more than 20 years was significantly correlated with worse 10-year graft survival. Kidneys from donors older than 55 years of age showed significantly compromised graft outcomes when transplanted into recipients younger than 30 years of age, but not in older recipients. Graft survival in transplants using old-to-old allocation was not different from that of young-to-young allocation. In cases of older donors, a lower DRAG between older donors and older recipients showed more favorable graft outcomes than a higher DRAG between older donors and younger recipients. Conclusions: This study demonstrated that DRAG may serve as a prognostic factor for predicting graft outcomes after LDKT. Additionally, we showed that transplantation of older donor kidneys via living donation is justified in appropriately chosen age-matched recipients.