Comparison between C0 and C2 monitoring in de novo renal transplant recipients: retrospective analysis of a single-center experience.

Background. Monitoring immunosuppression with cyclosporine microemulsion formulation (CsA-MEF) by using 2-hour CsA blood levels (C2) has been strongly recommended after kidney transplantation. The aim of our study was to evaluate the impact of C2 monitoring on the clinical outcome early after transplantation in a single-center setting. Methods. Nonsensitized, consecutive, de novo cadaveric kidney-transplant recipients were treated with CsA-MEF, mycophenolate mofetil, and steroids. Patients receiving transplants after January 2002 (n=89) were prospectively monitored by C2 levels (target: 1,500±200 ng/mL [fluorescence-polarization immunoassay]). They were retrospectively compared with the patients receiving transplants during 2001 (n=88) who had been monitored by CO levels (target: 250±50 ng/mL). Results. In the intention-to-treat analysis, 40 (45.4%) patients in the CO group and 25 (28.1 %) patients in the C2 group received treatment for rejection (P=0.017). The incidence of histologically verified rejection of Banff grade I or higher was 20.45% in the CO group and 13.48% in the C2 group (P=0.235). In the per-protocol analysis, incidence of treated rejection was 24.7%, and incidence of histologically verified rejection of Banff grade I or higher was 12.35% in the C2 group (P=0.004 and 0.160, respectively, vs. C0). Mean CsA-MEF doses were 1.7 to 2 times higher in the C2 group than in the CO group throughout follow-up (P=0.019). In the C2 group, target C2 levels were achieved on average 4 days after transplantation, and there was no significant difference in C2 levels between patients who rejected and patients who did not reject. Conclusion. Kidney-transplant recipients monitored by C2 levels receive significantly higher doses of CsA-MEF and have a lower incidence of early acute allograft rejection than patients monitored by CO levels. In C2 monitored patients, C2 levels are not predictive for the incidence of early allograft rejection.