*Purpose: Beginning in 2016, our center implemented a protocol change to thymoglobulin (r-ATG) induction dosing in kidney transplant recipients at low rejection risk from 5 mg/kg to 3 mg/kg cumulative dose. The co-primary outcome of the study was to examine differences in rejection rates at 1 and 2 years post-transplant between the two dosing groups. Secondary outcomes included GFR, graft loss, and death rates at 1 and 2 years. Differences in the development of CMV or BKV viremia, and cancer were also examined.

*Methods: This study was a retrospective analysis of patients undergoing kidney transplantation between 1/3/15 and 6/20/17 at a single center. Low risk patients eligible for 3 mg/kg r-ATG dosing included individuals age >40 years, first transplant, PRA <20%, non-African American race, <2 DR mismatches, and negative crossmatch at the time of transplant. Rejection was defined as AMR or ACR Banff 1b and above. Chi-square test or independent samples t-test were utilized where appropriate to evaluate differences.

*Results: Sixty kidney transplant recipients received 3 mg/kg r-ATG compared to 5 mg/kg (n=279). As expected, the patients who received 3 mg/kg were significantly younger with fewer past transplants and DR mismatches as seen in Table 1. The primary outcome of rejection after transplant at 1 year was 1.7% in the 3 mg/kg group vs 3.9% in the 5 mg/kg group (p=0.39). There was no difference between groups in graft loss, patient death, or GFR at 1 and 2 years post-transplant seen in Table 2. Similar rates of CMV viremia, BK viremia, and cancer were seen in both groups at 2-year follow-up.

Table 1

Table 2

*Conclusions: Similar rates of rejection, graft loss, infection, and cancer were observed in low risk kidney transplant recipients who received 3 mg/kg of r-ATG for induction compared to 5 mg/kg cumulative dosing.

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