Timing of rabbit antithymocyte globulin induction therapy in kidney transplantation: an observational cohort study.

Background: Literature on the timing of rabbit antithymocyte globulin (rATG) induction and its effects on kidney transplant outcomes is limited. The manufacturer recommends that the first dose be given intra-operatively, however this may present clinical practice risks and challenges. Our objective was to assess the impact of the timing of the first dose of rATG on kidney transplant outcomes.

Methods: Incident kidney transplant recipients (KTR) from January 2002 to December 2009 receiving the first dose of rATG post-operatively (Post, n = 353) or before reperfusion (Pre, n = 124) were evaluated. Outcomes assessed included eGFR at 1-year, delta eGFR (12 versus 1 month), and incidence of biopsy-proven acute rejection, graft loss, death, and a composite of the time-to-event outcomes. The impact of timing on outcomes was adjusted for potential confounders and assessed using linear and Cox regression models.

Results: Among 435 KTR surviving with function to 12 months post-transplant, there was no significant difference in mean estimated glomerular filtration rate or eGFR (55.0 versus 56.7 mL/min, P = 0.46) and delta eGFR (1.8 versus 0.3 mL/min, P = 0.40) in Post versus Pre groups, respectively. At a median follow-up of 3 years, the composite endpoint (time to first biopsy-proven acute rejection, graft loss, or death) was similar by timing group (adjusted HR = 0.94; 95% CI: 0.58, 1.53, P = 0.81) in the total study population.

Conclusions: Timing of rATG had no appreciable impact on clinically relevant endpoints in this study cohort. These results support consideration of more flexible timing of the first dose of rATG induction in KTR.