Time-dependent risk factors influencing the long-term outcome in living renal allografts - Donor age is a crucial risk factor for long-term graft survival more than 5 years after transplantation

Background. Most investigations have revealed that the improvement in early graft survival has not resulted in a corresponding improvement in long-ter m graft survival. The risk factors for long-term graft survival should be c larified. Methods. A single-center experience of 1100 consecutive renal transplant re cipients who received kidneys from living donors from 1983 to 1998 was revi ewed to clarify the time dependency of risk factors for long-term graft sur vival. We examined various possible risk factors, including HLA-AB and -DR mismatches, ABO-blood group incompatibility, graft weight, donor age and se x, recipient age and sex, and the presence or absence of acute rejection by using the time-dependent, nonproportional. Cox's hazards model. Results. Acute rejection episode, donor age, HLA-AB 4-antigen mismatches, A BO-incompatible transplantation, smaller kidney weight compared with the pa tient's body weight (Kw/Bw ratio less than 2.67), and transplantation from an unrelated living donor were risk factors for long-term graft outcome. Mu ltivariate analysis for time-dependent risk factors showed that donor age o f more than 60 years was the most important risk factor for long-term graft failure after 5 years posttransplantation (hazard ratio: 2.57). In contras t, acute rejection, ABO incompatibility, and nonrelated donors were signifi cant risk factors for short-term graft failure within 5 years after kidney transplantation (hazard ratios: 2.68, 1.57, and 1.69, respectively). Conclusions. Donor age of more than 60 years was a crucial risk factor affe cting long-term graft survival. In contrast, acute rejection, ABO incompati bility, and nonrelated donors were significant risk factors for short-term graft failure.