Pre-transplant Varicella Vaccination is Cost-effective in Pediatric Renal Transplantation

Abstract

694 Varicella (VZV) infection post-transplant may result in severe complications, including allograft rejection, pneumonitis, hepatitis, encephalitis or death. Because of this, transplanted non-VZV immune children exposed to VZV are typically given VZV Zoster Immune Globulin (VZIG) as prophylaxis; if VZIG prophylaxis fails or is not given and infection develops, these children are admitted and treated with parenteral acyclovir to prevent severe complications. Since both VZIG and hospitalization are costly, prevention of VZV infection by vaccination could potentially result in significant cost savings. To test this assumption we developed a decision analysis model (Data 3.0, TreeAge, Inc.) to evaluate the cost-effectiveness of vaccinating patients with chronic renal failure (CRF) against VZV prior to renal transplant. Baseline assumptions in the model included: vaccinated patients received two doses of VZV vaccine, VZV vaccination was 98% protective, 70% of the patients were exposed to VZV, when exposed 90% develop infection, and 90% of known exposures were treated with VZIG. Baseline cost assumptions: VZIG, $250; hospitalization for acyclovir, $5,000; VZV vaccination, $200; outpatient VZV infection treated with oral acyclovir, $1,200. In this analysis, only patients with no prior history of VZV infection were modeled. Results: Under baseline assumptions, vaccination for VZV pre-transplant was a cost-effective strategy with a cost of $250 per patient vaccinated compared to $2700 per patient not vaccinated. The magnitude of cost savings from vaccination was sensitive to variations in the cost of VZV vaccine, the percent of patients hospitalized for acyclovir, and the percent of patients exposed to VZV infection. Sensitivity analysis (one and two way) confirmed that vaccination was the dominant cost effective strategy under all conditions examined. Conclusions: From our model we conclude: 1) Vaccination for VZV pre-transplant is cost-effective for patients with CRF. 2) The magnitude of cost savings is sensitive to the cost of hospitalization, the percent of patients exposed to VZV, and the cost of VZV vaccination. Pending results of ongoing studies of the safety and efficacy of VZV vaccine in children with CRF, we reccommend that VZV vaccine be given to all children with CRF.