Predictors of Renal Function Improvement Following Tacrolimus Conversion in Cyclosporine-Treated Kidney Transplant Recipients

The objective of this study was to evaluate the relationship between variability of cyclosporine (CsA) absorption and tacrolimus (TAC) conversion seeking factors that predict improvement in allograft function after TAC conversion. We performed a retrospective study of 44 adult kidney transplant recipients undergoing conversion from CsA to TAC-based immunosuppression. Before TAC conversion, patients had complete, consecutive, 6 monthly C2 levels and a follow-up duration beyond 6 months after TAC conversion. The patients were divided into 2 groups: one (n = 23) with low variability of CsA absorption and one (n = 21) with high variability of CsA absorption. At TAC conversion, the estimated glomerular filtration rate (eGFR) was similar in both patient groups. Six months after TAC conversion, eGFR improved in both groups. Stepwise regression analysis revealed the ΔSCr6 (change in serum creatinine level at 6 months) to be independently associated with the preconversion serum creatinine (SCr; P < .0001) and the percent coefficient of variation (%CV) of SCr (P = .0034). ΔSCr6 was inversely associated with posttransplantation years (P = .0033), and 6-month TAC blood levels (P = .0053). The ΔSCr6 was not associated with variability of oral CsA absorption. The cutoff value of baseline SCr at TAC conversion differentiated an increase in or reduction of SCr to be about 1.0 mg/dL. Our study of CsA-treated kidney transplant recipients who underwent TAC conversion showed that a preconversion SCr > 1.0 mg/dL, a high variability of SCr, and early TAC conversion predicted greater short-term benefit on graft function.