(749) The Ideal Scenario: Dosing IVIG Using IBW Versus ABW in Pediatric Autoimmune Encephalitis

Introduction: Autoimmune encephalitis can be empirically treated with intravenous immunoglobulin (IVIG), corticosteroids, or plasmapheresis. Lucile Packard Children’s Hospital Stanford implemented IVIG dosing by ideal body weight (IBW) for patients whose body mass index (BMI) is greater than the 95th percentile. The objective of this study is to determine if patients with autoimmune encephalitis who received IVIG dose by IBW vs actual body weight (ABW) required an increase in interventions.

Methods: This study was performed using a retrospective chart review of patients with suspected or diagnosed autoimmune encephalitis who received at least 1 dose of IVIG from June 26, 2018 to August 4, 2022. Demographic data included: patient age, weight, height, IBW, BMI, outside hospital interventions prior to admission. The primary outcome was the need for additional interventions including corticosteroids, rituximab, tocilizumab, repeat IVIG, and plasmapheresis. Secondary outcomes include: pediatric intensive care unit (PICU) length of stay (LOS), hospital LOS, overall cost of IVIG, rituximab, and tocilizumab, and disposition at discharge.

Results: A total of 16 patients were administered IVIG for suspected autoimmune encephalitis. 13 patients received IVIG dosed on actual body weight and 3 patients received IVIG dosed on ideal body weight. Four patients in the ABW group and zero patients in the IBW group required secondary interventions after the initial course of IVIG, (p = 1). There was not a statistically significant difference in secondary outcomes between the IBW and ABW groups.

Conclusions: IBW dosing of IVIG for suspected autoimmune encephalitis did not have a statistically significant difference in need for additional interventions compared to patients who received IVIG dose based on ABW.