There is significant variability in antithymocyte globulin (ATG) dosing practices among centers. In the obese population, use of total body weight (TBW) vs. adjusted body weight (ABW) result in large differences in ATG dose. This study evaluates the three year clinical outcomes and economic impact associated with ABW vs. TBW dosing of ATG in renal transplant patients.

This is a retrospective single center study of adult obese (BMI ≥ 30) solitary renal transplant patients from 2011 to 2014. All patients received either 4.5 mg/kg ATG for immediate graft function or 6 mg/kg for delayed graft function n (DGF) based on respective dosing weight. Three year patient and graft survival, renal function, infection, and rejection prevalence were reported. Univariate and Kaplan-Meier analysis was performed and p<0.05 was consider significant.

55 patients with BMI ≥ 30 underwent renal transplantation (31 in the ABW and 24 in the TBW group). Baseline demographics were similar between groups including percent primary transplant (ABW: 90 % vs TBW: 92%, p=NS) BMI (34.4 vs 34.3, p=NS), rate of delayed graft function (35.5 vs 12.5%, p=NS). Patient survival at three years (100% vs 96%; p=NS) and graft survival at three years (97% vs 92%, p=NS) were comparable. There was no significant difference in mean eGFR at 3, 6, 12, 18, 24, 30 or 36 months post-transplant. Rates of acute cellular rejection at 6 (10 vs 0, p=NS), 12 (10 vs 0, p=NS), and 36 months (10 vs 8, p=NS) and rates of antibody mediated rejection at 6(3 vs 8, p=NS), 12 (7 vs 8, p=NS), and 36 (7 vs 8, p=NS) months were similar. CMV viremia rates were comparable up to one year post transplant (16 vs 16%, p=NS). BK viremia rates were comparable up to one year post transplant (7 vs 17%, p=NS). There was no difference in the intended ATG total mean dose per kg (5.3 vs 5.6 mg/kg, p=NS), however, when factoring the dosing weight, the total mean doses were significantly less in the ABW group (434 ± 85mg vs 551 ± 102 mg, p<0.01). This difference in ATG represents a reduction in 2% reduction in use and mean savings per patient of $4239 based on the 2017 average wholesale price.

These data suggest ABW can be used safely to determine ATG dosing, while maintaining excellent renal function, rejection rates, and patient/graft survival with an improved value of care.

CITATION INFORMATION: Dann J., Agarwal A., Bradley M., Ally W. Adjusted Body Weight Dosing of Rabbit Antithymocyte Globulin in Obese Renal Transplant Recipients Preserves Excellent Clinical Outcomes at 3 Years and Improves the Value of Care Am J Transplant. 2017;17 (suppl 3).

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