Center and other factor effects in recipients of living-donor kidney transplants.

1. LIVING DONOR KIDNEY TRANSPLANTS: Using 1996-2001 UNOS Registry data, we assessed the joint influence of center, 19 pre- and 5 posttransplant factors on renal allograft function in 21,830 patients transplanted with living donor kidneys. During an initial risk period, 21,033 recipients were projected to keep their grafts through one year (an average 96.4% one-year graft survival), and, in a second risk period, 17,775 recipients were projected to keep their grafts through 5 years (84.5% conditional 5-year graft survival after surviving one year posttransplant). 2. CENTER EFFECTS: Following multivariate log-linear analysis, 57.5% and 26.5% of assignable variation in one- and 5-year living-donor graft survival rates were due to the variation across 234 transplant centers. Center effect dominated other factors in influencing early outcomes among living kidney donor transplants. A program's size was associated with this center effect since all large centers (400+ living donor kidneys) had better-than-average one-year graft survival rates, whereas smaller centers (< or = 100 grafts) had wide ranges in short-term outcomes (87-100%). Center size did not play a role in explaining long-term variation, and the extent to which uniformity in care remains the responsibility of the original center needs to be investigated. 3. PRETRANSPLANT FACTOR EFFECTS: The impact of the 19 pretransplant cofactors on short-term outcomes among living donor transplants was clinically small--adjusted one-year graft survival rates across all categories exceeded 94%. However, their long-term effects were stronger and more typical of cadaveric results. The following 4 factors, each explaining > 10% of the assignable variation in conditional 5-year graft survival, were ranked and independently yielded poor results: 1) kidneys from parental donors; 2) grafts in male recipients; 3) teenage/adult recipients (> 12 years); and 4) black recipients. Recipient's original disease and body mass index, donor's race and age, and HLA matching were highly significant factors, but their impact on long-term graft survival was less than those observed previously in cadaveric renal transplants. 4. POSTTRANSPLANT FACTOR EFFECTS: Short- and long-term outcomes were relatively stable regardless of the maintenance drug initiated at hospital discharge. Living donor transplant outcomes were similar for Neoral versus Tacrolimus and for MMF versus azathioprine. Kidney graft survival among living donor transplants was strongly affected by delays in graft function or acute rejection episodes. 5.
CONCLUSIONS: During the first year posttransplant, the benefits of receiving a living donor kidney (versus a cadaver kidney) mitigate negative cofactor risks of graft failure. Beyond one-year, recipients of living donor kidneys are subjected to the same deleterious effects from cofactors and early posttransplant events that impact the long-term graft survival following cadaveric transplantation.