THE RELATIVE EFFECTS OF FK506 AND CYCLOSPORINE ON SHORT-TERM AND LONG-TERM KIDNEY GRAFT SURVIVAL2

As reported to the UNOS Kidney Transplant Registry from 1988 through 1 994, 544 first cadaveric kidney graft recipients have been discharged with maintenance tacrolimus (FK506) therapy, Total follow-up data was available on 38,057 first cadaveric kidney transplants from 224 center s reporting at least 10 grafts each to the Registry. We examined the e ffects of FK506 on short- and long-term renal graft outcomes and compa red its effect with that of cyclosporine (CsA), Three drug categories (FK506, CsA, and Other) were defined using therapies through discharge (i.e., grafts surviving more than 15 days), The 1-year graft survival rate of 2366 recipients receiving Other therapies was 69.2 +/- 1.0%. By comparison, both FK506 and CsA recipients demonstrated significantl y improved early graft function (l-yr survival rates of 91.1 +/- 1.3% and 86.6 +/- 0.2%, respectively), The long-term graft survival, as mea sured by half-lives, varied little (8-9 yr) between Other and CsA grou ps, but was significantly (P = 0.04) increased for FK506 patients (to similar to 14 yrs), CsA usage was reported by all 224 transplant cente rs, whereas FK506 was administered at only 24 (11%) centers, Using mul tivariate methods, a drug regimen's graft survival rate was adjusted f or center effects and 19 covariates. The adjusted FK506 and CsA cadave ric graft survival rates at 1 and 3 years mirrored their unadjusted ra tes, indicating that demographic differences did not confound our resu lts, Eased on this study, FK506 appears to be the first therapeutic ag ent to significantly improve long-term kidney graft survival rates.