Maintaining a tacrolimus trough level greater than 7 ng/mL may help prevent acute rejection in the first month after kidney transplantation, a new study finds.
In a study of 160 kidney transplant recipients, 14 (8.8%) experienced biopsy-proven acute rejection within the first month, mainly T cell-mediated rejection. Acute rejection rates significantly differed by tacrolimus trough level: 17.6%, 15.5%, and 3.0% of patients with tacrolimus trough levels less than 4, 4-7 and more than 7 ng/mL, respectively. No one with a tacrolimus trough level greater than 12 ng/mL experienced acute rejection.
The target range of tacrolimus trough levels has changed over time. In 2019, a European consensus report recommended a higher range of 7-12 ng/mL.
Tacrolimus trough levels greater than 7 ng/mL were significantly associated with an 86% lower risk of acute rejection in the first month compared with levels of 4-7 ng/mL, Thi Lien Huong Nguyen, PhD, of Hanoi University of Pharmacy in Vietnam, and colleagues reported in BMC Nephrology.
The time in therapeutic range of tacrolimus was significantly lower for the acute rejection than no rejection group: 10% vs 37%. In the AR group, 4 patients did not have any time in the target range of 7–12 ng/mL. For every 10% increase in time within the therapeutic range of tacrolimus, the risk of acute rejection significantly decreased by 28%.
“The result of this study shows the risk of early [acute rejection] is significantly decreased by achieving [tacrolimus trough levels] early and maintaining it within the threshold of 7-12 ng/ml,” the investigators wrote.
The study did not examine the association between tacrolimus levels and infectious disease complications or post-transplantation diabetes.
Nguyen TVA, Nguyen HD, Nguyen TLH, et al. Higher tacrolimus trough levels and time in the therapeutic range are associated with the risk of acute rejection in the first month after renal transplantation. BMC Nephrol. 2023 May 8;24(1):131. doi:10.1186/s12882-023-03188-0