Background: We report the influence of race on transplant outcomes in the Department of Defense (DOD) system.
Methods: Retrospective cohort analysis of all kidney transplants performed at WRAMC from 1996 to 2005. Kaplan-Meier analysis was used to assess for differences in graft survival, and Cox regression was used to calculate adjusted hazard ratios for graft loss. For our analyses, we used the cutoff of 6 years (year 2000) when we introduced thymoglobulin induction; maintenance immunosuppression consisted of mycophenolate mofetil and tacrolimus, and rapid steroid taper (completed withdrawal at 6 weeks) was used for all patients.
Results: There were 220 transplants (91 Blacks, 107 Caucasians and 22 Asians). Because the curve for graft survival for Blacks over time violated the proportional hazards assumption (at 6 years post-transplant), analysis was segregated into two segments. Through 6 years of follow-up, graft survival was 77% for Blacks and 81% for non-Blacks (p = 0.74 by log rank). Through 9 potential years of follow-up, graft survival for Blacks was 56% and 78% for Whites (p = 0.005). In Cox regression analysis, Black race, compared with non-Black race, was not significantly associated with graft loss at 6 years, but was significantly associated with graft loss occurring after 6 years.
Conclusions: In the DOD health system, no significant differences were seen in graft survival among recipients of different races at 6 years. Black recipients who received a kidney transplant before the year 2000 showed decreased graft survival compared to non-Blacks. This was consistent with change in immunosuppressive regimen in our institution with the introduction of thymoglobulin induction and maintenance therapy with tacrolimus, mycophenolate mofetil and withdrawal of prednisone at 6 weeks.