2024 American Academy of Neurology Abstract Website

Objective:

To describe infectious and autoimmune encephalitis (IAE) population characteristics and immunoglobulin (IG) prescribing patterns.

Background:

IG therapy is a widely accepted treatment for IAE, an umbrella term for immune-mediated neuropsychiatric disorders and autoimmune conditions of the nervous system. Because the differential diagnosis process and lack of controlled trials can lead to complications (e.g., payor denials, delayed treatment), this complex specialty pharmacy implemented a clinical program to fulfill unmet needs in this patient population.

Design/Methods:

A retrospective medical record review was performed for patients enrolled in this organization’s IAE clinical program from 10/01/2022-05/31/2023, including medical history, triggering events, IAE symptoms, and pharmacy dispensing history.

Results:

Forty-seven IAE patients received IG therapy within the study period (66% male). The average age of diagnosis was 20 years old.

Sixty-eight triggering events identified included infections, stress, tick bites without confirmed infection, and primary immunodeficiency. Fifteen patients had unknown triggers.

Patients sought care from an average of 4 different specialists (range 1-12), most frequently neurology, psychiatry, infectious disease, pediatrics, allergy/immunology, and neuroimmunology.

Symptoms reported included psychiatric symptoms 74%, obsessive-compulsive behaviors 70%, cognitive deficits 64%, tics/involuntary movements 60%, autonomic irregularities 43%, headaches/migraines 43%, sensory perception issues 40%, separation anxiety 38%, and loss in motor skills 21%.

Forty-four patients received intravenous IG therapy. Average dosing was 1.6 g/kg with frequencies of every 4 weeks (68%), one-time orders (13%), and every 8 weeks (9%). Three patients received subcutaneous IG at an average of 63.33 grams monthly (1.6 g/kg) divided into weekly or biweekly doses. Most patients (53%) were IG-naïve at the time of referral to this complex specialty pharmacy.

Conclusions:

IAE is a complex condition requiring multidisciplinary support. While a majority of patients identified triggering events preceding their IAE diagnosis, 32% had unidentified triggers. This study demonstrates that long-term IG therapy is prescribed more often than one-time IG orders for IAE diagnoses.