Lower tacrolimus time in therapeutic range is associated with inferior outcomes in adult liver transplant recipients

Abstract Previous studies on solid organ transplantation have reported that a low time in therapeutic range (TTR) of tacrolimus increases the risk of poor outcomes. However, the reproducibility of the findings in liver transplantation has not yet been confirmed. The TTR, coefficient of variation (CV) and standard deviation (SD) were calculated for 207 adult liver transplant patients from the date of transplantation until the first episode of acute rejection (AR), graft loss, acute kidney injury (AKI), biliary complications, infection or the last follow‐up. Kaplan–Meier curves, log‐rank tests and Cox regression analyses were performed. Sixty‐one (29.5%) patients reached the composite endpoint of AR, biliary complications and graft loss. The log‐rank test indicated that the low TTR group had an increased risk of the composite endpoint ( P < 0.001), AKI ( P < 0.001) and infection ( P < 0.001). Multivariate Cox regression analyses revealed that a 10% decrease in TTR was associated with an increased hazard for composite endpoint (hazard ratio [HR]: 1.185, P = 0.010), AKI (HR: 1.355, P < 0.001) and infection (HR: 1.357, P < 0.001). Unexpectedly, SD and CV demonstrated no association with the above‐mentioned inferior outcomes. Compared with SD and CV, the TTR of tacrolimus was more correlated with inferior outcomes and may be a novel indicator for predicting the prognosis of liver transplantation.