Abstract
INTRODUCTION: Outcomes are poor in kidney transplant (KTx) recipients with sub-therapeutic tacrolimus troughs. It is unknown if rabbit anti-thymocyte globulin (rATG) induction delays the deleterious impact of early sub-therapeutic tacrolimus troughs. The study aims compared short-term graft outcomes of KTx recipients stratified by tacrolimus troughs at the time of discharge from index admission. METHODS: Single-center retrospective cohort study compared adult KTx recipients with sub-therapeutic versus therapeutic discharge tacrolimus troughs (defined as < vs. ≥ 8 ng/mL). Successful primary/secondary KTx between 10/2017 and 12/2019, who received rATG induction and tacrolimus-based immunosuppression and had an index admission length of stay ≤5 days were included. The primary composite outcome analyzed the 3-month risk of rejection, graft loss, or de novo donor-specific antibodies (dnDSA). Cox regression analysis assessed the association of early sub-therapeutic tacrolimus troughs on short-term graft outcomes. RESULTS: Among 411 recipients included, 335 (81.5%) were discharged with a tacrolimus trough <8 ng/mL versus 76 (18%) ≥8 ng/mL. Our population consisted of 30% black/non-Hispanic, 10% with a history of previous KTx, 60% deceased donors, and low cPRA (median 0%), which was in the low immunological risk range. No significant difference was identified in the primary outcome (13.4% vs. 9.2%, p = 0.44). Cox regression analysis identified no association between sub-therapeutic tacrolimus troughs at discharge and the primary outcome. CONCLUSION: KTx recipients receiving rATG induction, discharged with sub-therapeutic tacrolimus troughs (<8 ng/mL) have comparable short-term graft outcomes versus those discharged with therapeutic troughs (≥8 ng/mL). This suggests that delaying discharge to reach therapeutic troughs is not necessary.