Abstract Details

Title Frequency and Cost of Anti-neural Antibody Testing for Autoimmune Encephalitis in a Large Canadian Health Region

Topic Autoimmune Neurology

Presentation(s) S4 - Autoimmune Neurology: Autoimmune Encephalitis and Neuronal Autoantibodies (2:48 PM-3:00 PM)

Poster/Presentation
Number 010

Background There is increasing interest in and awareness of anti-neural antibody panels for AIE. Emerging research suggests that indiscriminate ordering of anti-neural antibodies for AIE contributes to misdiagnosis and inflated healthcare costs. It is unknown if the frequency of anti-neural antibody testing has increased over time. Additionally, population-based estimates of testing frequency and subsequent healthcare expenditures are scarce.

Objective To determine the frequency and healthcare expenditure of anti-neural antibody testing for autoimmune encephalitis (AIE) in a large Canadian population.

Design/Methods Alberta, Canada has a centralized, publicly delivered healthcare system which is divided into discrete healthcare zones. The Calgary Zone provides healthcare to 1.5 million individuals, and nearly all autoantibody testing is performed by Mitogen Dx Laboratories (MDx). We obtained a comprehensive list of all AIE or paraneoplastic antibody tests performed in serum or cerebrospinal fluid (CSF) during a 3-year period spanning from Jan 1, 2018 to Dec 31, 2020 from MDx. We included individuals where the pattern of tested anti-neural antibodies suggested clinical suspicion for AIE.

Results In total, 881 individuals had anti-neural antibody testing for AIE in serum or CSF (881/1,500,639 = 58.7/100,000 population) at a cost of $781,306 over 3 years. Mean costs were $260,435/year and $887/person. The number of individuals tested slightly increased over time (2018 = 293 individuals, 2019 = 304 individuals, 2020 = 317 individuals). In total, 821 (93.2%) individuals were tested for anti-NMDA, 794 (90.1%) for anti-VGKC (including anti-LGI-1 and anti-CASPR2), 574 (65.2%) for paraneoplastic antibodies and 63 (7.2%) for anti-IgLON5. At least one autoantibody resulted as positive for 64/881 (7.3%) individuals (4.3/100,000 population). Of 469 adults who were seen in an academic centre, 42/469 (9.0%) were positive, of which 10/469 (2.1%) were pathogenic.

Conclusions Detection of pathogenic AIE anti-neural antibodies was rare despite high frequency and cost of testing. Frequency of testing marginally increased over 3 years.

Authors/Disclosures
Jodie Roberts, MD PRESENTER	An immediate family member of Dr. Roberts has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Amylyx Pharmaceuticals. Dr. Roberts has received personal compensation in the range of $500-$4,999 for serving as an Editor, Associate Editor, or Editorial Advisory Board Member for American Academy of Neurology. The institution of Dr. Roberts has received research support from Canadian Network of MS Clinics. Dr. Roberts has received research support from Rebecca Hotchkiss International Exchange Program. The institution of Dr. Roberts has received research support from University of Calgary Medical Group Helios Award. Dr. Roberts has received personal compensation in the range of $500-$4,999 for serving as a Speaker with Novartis. Dr. Roberts has received personal compensation in the range of $5,000-$9,999 for serving as a Speaker with EMD Serono.
Jamie Greenfield	No disclosure on file
Megan A. Yaraskavitch, MD (Alberta Health Services)	Dr. Yaraskavitch has received personal compensation in the range of $0-$499 for serving on a Speakers Bureau for Allergan, an AbbVie Company.
Christopher Hahn, MD (Alberta Health Services)	Dr. Hahn has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Akcea. Dr. Hahn has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Anylim.