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-term graft survival. The risk factors for long-term graft survival should be clarified.


METHODS
A single-center experience of 1100 consecutive renal transplant recipients who received kidneys from living donors from 1983 to 1998 was reviewed to clarify the time dependency of risk factors for long-term graft survival. We examined various possible risk factors, including HLA-AB and -DR mismatches, ABO-blood group incompatibility, graft weight, donor age and sex, 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, ABO-incompatible transplantation, smaller kidney weight compared with the patient'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. Multivariate analysis for time-dependent risk factors showed that donor age of more than 60 years was the most important risk factor for long-term graft failure after 5 years posttransplantation (hazard ratio: 2.57). In contrast, acute rejection, ABO incompatibility, and nonrelated donors were significant 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 affecting long-term graft survival. In contrast, acute rejection, ABO incompatibility, and nonrelated donors were significant risk factors for short-term graft failure.
Toma
H
H
Department of Urology, Tokyo Women's Medical University, Shinjuku-ku, Tokyo, 162-8666 Japan. toma@kc.twmu.ac.jp
Tanabe
K
K
Tokumoto
T
T
Shimizu
T
T
Shimmura
H
H
D000017:ABO Blood-Group System; D000293:Adolescent; D000328:Adult; D000368:Aged; D002648:Child; D002675:Child, Preschool; D005260:Female; D006085:Graft Survival; D006680:HLA Antigens; D006801:Humans; D007223:Infant; D016030:Kidney Transplantation / Q000009:adverse effects* / Q000276:immunology / Q000401:mortality; D008297:Male; D008875:Middle Aged; D016016:Proportional Hazards Models; D012307:Risk Factors; D015996:Survival Rate; D013997:Time Factors; D014019:Tissue Donors
D000017:ABO Blood-Group System; D006680:HLA Antigens