Effectiveness and Safety of Reduced Thymoglobulin Dosing in Low-Risk Kidney Transplant Recipients.

Introduction: Thymoglobulin, a lymphocyte-depleting agent, is widely used for induction immunosuppression in kidney transplantation. Despite guideline support, there is no standardized dosing recommendation, resulting in variability across centers. In April 2022, our institution reduced its institutional practice thymoglobulin dose from 4.5 to 3 mg/kg for low-risk kidney transplant recipients. This study aimed to evaluate the noninferiority of the reduced dose compared to the prior regimen in terms of effectiveness and safety. Methods: This single-center retrospective noninferiority cohort study of low-risk kidney transplant recipients was conducted from April 2020 to April 2024. Patients received either 3 or 4.5 mg/kg of thymoglobulin. The primary outcome was a composite of biopsy-proven or suspected acute rejection, graft loss, or death within 6 months posttransplant. Secondary outcomes included leukopenia, thrombocytopenia, infections, delayed graft function, eGFR, malignancies, and hospital length of stay. Results: A total of 196 patients were included (116 in 4.5 mg/kg; 80 in 3 mg/kg). The primary outcome occurred in 11% and 3% of patients, respectively (risk difference -8.7%, 95% CI -15.4 to -2.0; p = 0.024). The reduced-dose group experienced significantly lower rates of leukopenia, thrombocytopenia, and viral infections. Conclusion: A 3 mg/kg thymoglobulin dose is noninferior to 4.5 mg/kg and is associated with improved safety in low-risk kidney transplant recipients.