Antithymocyte Induction Dosing And Incidence Of Opportunistic Viral Infections Using Steroid-Free Maintenance Immunosuppression

Background Currently, there is limited literature evaluating rATG induction dosing and incidence of opportunistic viral infections when using steroid-free maintenance immunosuppression.Methods This single-center, retrospective, study compared high rATG (>4.5 mg/kg) versus low (<4.5 mg/kg) induction dosing and the overall incidence of early opportunistic viral infection at 180 days in the setting of maintenance immunosuppression consisting of tacrolimus, mycophenolate, rapid steroid withdrawal, and a tiered antiviral prevention strategy based on donor-recipient Cytomegalovirus (CMV) serostatus.Results A total of 209 patients were included; 76 patients received low-dose and 133 patients received high-dose rATG. Incidence of overall opportunistic viral infection occurred more frequently in patients who received high compared to low dose (29.8% vs 25% p = .030). Incidence of CMV infection was also significantly increased in the high-dose group (31.6% vs 18.4% p = .039). In a multivariable model, rATG dose, as a continuous variable, remained a significant independent predictor of infection along with CMV risk (OR 1.46, 95% CI 1.02-2.09) controlling for age and CMV risk. There were no differences in graft-related outcomes at 180 days.Conclusion Higher cumulative rATG induction dose was associated with increased incidence of opportunistic viral infections, in the setting of a steroid-free maintenance immunosuppression in the early post-transplant period.