MYCOPHENOLATE MOFETIL REDUCES THE RISK OF ACUTE REJECTION LESS IN AFRICAN-AMERICAN THAN IN CAUCASIAN KIDNEY RECIPIENTS

Background. Multicenter clinical trials have shown that mycophenolate mofetil (MMF) reduces the risk of acute rejection, but it is unknown w hether African-Americans constitute a subgroup of recipients less like ly to benefit from MMF. Methods. This study compared the acute rejecti on rates within 6 months of kidney transplantation in MMF-treated tran splant patients with those on azathioprine (AZA) at a single center. T he study population consisted of 353 consecutive recipients of cadaver or living donor kidney transplants, African-Americans constituted 43% of the patients on AZA and 49% of the patients on MMF. Variables used in a Cox regression analysis included MMF immunosuppression, recipien t race, type of transplant, delayed graft function, postoperative immu ne induction, average cyclosporine trough level, and HLA mismatch, Res ults, Significantly fewer patients on MMF experienced a biopsy-proven rejection episode than those treated with AZA (24% vs, 42%, respective ly; relative risk [RR]=0.57, P=0.001), This decrease in risk was great er in Caucasian transplant recipients (MMF vs, AZA: 16% vs. 46%, RR=0. 35, P<0.001) than in African-American patients (32% vs, 36%, RR=0.88, P=0.6), Within each race stratum, the mean cyclosporine trough levels averaged over 2-week intervals were nearly identical for AZA-compared with MMF-treated patients, In the regression model, the effect of MMF on the incidence of rejection was again less in African-American than in Caucasian patients. Conclusions, Kidney recipients treated with MMF have a significantly lower risk of acute rejection within 6 months of transplantation than those given AZA. This reduction in risk is signi ficantly less in African-American recipients than Caucasians.