Tacrolimus Intrapatient Variability on Graft Outcomes in Adherent Renal Transplantation Patients: A Cross-Sectional Study.

Introduction: Tacrolimus is the mainstem of immunosuppressive therapy in kidney transplant patients. It has high intrapatient variability (Tac-IPV), which has been reported to affect graft function by predisposing patients to rejection or nephrotoxicity. We conducted this study with the aim of assessing the influence of Tac-IPV on 2-year graft function, biopsy-proven rejection, and infections in compliant renal recipients.

Methods: In this single-center retrospective analytic cross-sectional study, 250 patients who underwent transplantation from March 21, 2018, to March 20, 2020 and had at least three outpatient tacrolimus trough levels on the same daily dose 6 to 12 months after transplantation were recruited. Tac-IPV was defined as a coefficient variation of > 15%. Graft function, biopsy-proven rejection, cytomegalovirus (CMV) and BK virus viremia, and calcineurin inhibitor (CNI) toxicity were evaluated.

Results: Of 202 transplant recipients, 128 were included with a mean age of 45.48 ± 13.14 years. The median Tac-IPV was 13.28% with 43.75% of patients with Tac-IPV > 15%. There were no significant differences in graft function, rejection, CNI toxicity, and CMV viremia among the groups during the 24-month study (P > .05).  However, BK viremia was significantly higher among patients with Tac-IPV > 15% (13 vs. 2.9%, P = .042). The risk of antibody mediated rejection alone (22.7 vs. 2.9%) or any kind of rejection (22.7 vs. 11.8%) was significantly higher in patients with higher Tac-IPV, and in those who had mean trough levels below 7 ng/mL (P = .015, .032; respectively).

Conclusion: Tac-IPV is low in adherent patients (with the median of 13.28%) and maintaining tacrolimus trough level above 7 ng/mL can overcome the adverse graft outcome of Tac-IPV in compliant kidney transplant recipients. DOI: 10.52547/ijkd.7815.