*Purpose: Based on the United Network of Organ Sharing (UNOS) annual report, there has been an increase in the number of adults ages 65-74 waiting for kidney transplants (KT). Currently, there is limited data regarding induction agents in this age group, but anti-thymocyte globulin (ATG) continues to be the agent of choice in this population. The optimal dose remains to be determined as transplant centers have reported using doses ranging from a total dose of 3 to 5 mg/kg. Lower doses of ATG are intriguing given the lower immunogenicity seen in older KT patients. Lower doses may provide a decrease in infectious complications and cancer and improved cost-savings without compromising efficacy. The purpose of this study is to compare efficacy outcomes in older KT recipients who received either low-dose ATG (LD-ATG) 3 mg/kg or high-dose ATG (HD-ATG) 5 mg/kg for induction. Secondary endpoints include infectious complications and a cost-savings analysis.

*Methods: This is a single center, retrospective cohort study at a large academic medical center. Patients age 65 years and older who received a KT between November 1, 2012 and September 1, 2018 and received either LD-ATG or HD-ATG for induction were included. Patients were excluded if they experienced death prior to discharge, received a prior transplant or received multi-organ transplantation. Data was compared using Fisher’s exact test and Chi-Squared.

*Results: A total of 115 patients were screened for inclusion and 51 patients were included in this study: 32 received LD-ATG and 19 received HD-ATG. Maintenance immunosuppression included tacrolimus, mycophenolate, and prednisone for both groups. No statistically significant difference in biopsy proven acute rejection (BPAR) at 12 months post-transplant was noted between LD-ATG and HD-ATG (3.1% (1/32) vs 10.5% (1/19), respectively). There was no statistically significant difference in side effects and patient and graft survival between groups. For one patient, the average cost of LD-ATG estimated to be $7000 compared to the average cost of HD-ATG was $12000.

*Conclusions: The results of this study demonstrate there is no significant difference in BPAR, patient, and graft survival when LD-ATG or HD-ATG is given as induction in older KT recipients. This shows potential for cost savings and lower risk of side effects in this specialized population.

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