ABSTRACT
Purpose: Rabbit anti-thymocyte globulin (rATG) is a polyclonal antibody utilized for induction immunosuppression in high immunologic risk kidney transplant recipients. However, the optimal total dose of rATG has not been identified. Higher cumulative doses of rATG may be associated with an increased risk of adverse infectious and hematologic outcomes, while lower cumulative doses may not provide adequate immunosuppression to prevent acute rejection. In March 2020, the total rATG dose in our institution's induction protocol for kidney transplant recipients was reduced from 6 mg/kg to 4.5 mg/kg to avoid potential infectious complications from COVID- 19. The objective of this study is to compare the efficacy and safety between two different doses of rATG. Method(s): This was a single center, retrospective chart review of adult kidney transplant recipients who received rATG for induction between September 1, 2019 and August 31, 2020. Patients who received a total dose of 6 mg/kg rATG were compared to patients who received a total dose of 4.5 mg/kg. The primary outcome was biopsy proven acute rejection (BPAR) within 90 days of transplant. Secondary outcomes assessed incidence of infection, leukopenia, neutropenia, thrombocytopenia, and delayed graft function within 90 days of transplant. Result(s): Eighty-one adult kidney transplant recipients were included in this study;37 received 6 mg/kg of rATG and 44 received 4.5 mg/kg of rATG. Incidence of BPAR was significantly lower in the 6 mg/kg rATG group compared to the 4.5 mg/ kg group (2.7% vs 20.5%, p=0.02). The majority of rejection episodes were classified as borderline. Patients who had BPAR were treated with corticosteroids. The number of patients who had an infection was significantly lower in the 6 mg/kg group compared to 4.5 mg/kg group (21.6% vs 47.7%, p=0.02). There was a numerically lower incidence of delayed graft function in the 6 mg/kg group compared to the 4.5 mg/kg group (25.0% vs 43.2%, p=0.18). Incidence of leukopenia, neutropenia, and thrombocytopenia were similar between groups. Conclusion(s): In conclusion, a lower cumulative dose of rATG was associated with an increased risk of borderline rejection and a numerically higher incidence of delayed graft function.