Background: Dosing of rabbit anti-thymocyte globulin (rATG) induction in renal transplant recipients is highly variable by transplant center. Optimizing rATG dose becomes extremely important for centers that utilize steroid-avoidance protocols. Studies have shown that even small differences in rATG dose may increase risk of acute rejection. However, there is limited data in what the total cumulative rATG dose should be in obese renal transplant recipients and how dosing affects outcomes in this population.

Methods: In a retrospective study design, graft and patient outcomes were compared in obese renal transplant recipients (body mass index [BMI] 30 kg/m² or greater) who received either low dose rATG (5 mg/kg or less) or high dose rATG (greater than 5 mg/kg). Dose calculation for the study utilized actual body weight at time of transplant. Baseline characteristics and renal transplant outcomes were analyzed between the 2 groups using either a Chi-square test or Student's t-test where appropriate. Acute rejection was compared at 1-year. Analysis of 1, 3, and 5 year post-transplant outcomes included the following: glomerular filtration rate (GFR; based on the MDRD equation), graft survival, and patient survival.

Results: A total of 122 obese renal transplant recipients met inclusion criteria with a mean BMI of 38 kg/m². Mean age at the time of transplant was slightly higher in the high dose group (52.3 vs 47.6; P = 0.0268). Significantly more patients in the low dose group were African American (85.5% vs 71.7%; P < 0.0611). The groups had similar immunologic risk, indications for transplant, and maintenance immunosuppression (calcineurin inhibitor, mycophenolate, and 5-day steroid taper). No differences in acute rejection were noted within the first year after transplant (low-dose 27.5% vs high-dose 30.2%; P = 0.7482). Although there was no difference in GFR at 1 and 3 years post-transplant , at 5 years the GFR was significantly higher in the high dose group (59.23 vs 40.16; P = 0.0109).There was no difference in patient or graft survival at 1, 3, or 5 years.

Conclusion: In a steroid avoidance immunosuppression protocol, rATG dose greater than 5 mg/kg maintained GFR at 5-years to a greater extent than the lower dose group in obese renal transplant recipients.

CITATION INFORMATION: Jasiak N, Stromayer C, Thielke J, Chen J, Chen J, Talon B, Rubin-Tobar R, Benedetti E, West-Thielke P. Outcomes in Obese Renal Transplant Recipients Using High versus Low-Dose Thymoglobulin. Am J Transplant. 2016;16 (suppl 3).

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