Outcomes at four years after kidney transplantation in African-American kidney transplant patients in the era of modern immunosuppression: An analysis from the Mycophenolic Acid Observational Renal Transplant Registry

Purpose: African-American (AA) kidney transplant patients are at increased immunological risk and show attenuated tacrolimus absorption, and thus may be more prone to rejection following mycophenolic acid (MPA) dose reductions. An analysis was undertaken to assess outcomes in tacrolimus-treated AA kidney transplant patients receiving MPA.

Methods: The Mycophenolic Acid Observational Renal Transplant (MORE) registry is a prospective, observational study of de novo adult kidney transplant patients receiving MPA at 40 US centers.  

Results: The analysis included 218 AAs (149 enteric-coated mycophenolate sodium [EC-MPS], 69 mycophenolate mofetil [MMF]) and 686 non-AAs (467 EC-MPS, 219 MMF). Living donors were less frequent in AA recipients (24%) versus non-AAs (48%, p<0.01). AAs and non-AAs had similar mean tacrolimus trough levels throughout. More AAs versus non-AAs received steroids, but the mean steroid dose administered was similar. For AA patients, the full recommended MPA dose (1.44g EC-MPS, 2.0g MMF) was administered more frequently with EC-MPS than MMF at month 6 (56% versus 36%, p=0.02) and month 36 (47% versus 17%, p=0.03). Compared to non-AAs, AA patients experienced more frequent biopsy-proven acute rejection (BPAR) (19% versus 11%, p<0.01) with lower graft survival (89% versus 96%, log rank p<0.01 [Kaplan Meier]) but patient survival was similar (96% versus 94%, p=0.99). There were no significant differences in efficacy with EC-MPS versus MMF in AAs or non-AAs. Diabetes (17% versus 11%, p=0.02) and cardiovascular events (11% versus 6%, p=0.03) were more frequent in AAs versus non-AAs, but bone-related events were less frequent (8% versus 14%, p=0.02).

Conclusion: Despite similar tacrolimus exposure and greater use of steroids, BPAR and graft loss occurred more frequently in AAs versus non-AAs at four years post-transplant. In AA patients, full MPA dose was maintained more frequently with EC-MPS than MMF at months 6 and 36 but more intensive immunosuppression may still be required.