BACKGROUND Generalized myasthenia gravis (gMG) is an antibody-mediated disorder that interferes with the function of acetylcholine receptors important to muscle contraction. While crises are high-cost events, there is limited published evidence for associated costs and healthcare resource utilization (HRU) for the US.

OBJECTIVES Evaluate direct costs in adults with gMG (including crisis events) using administrative claims data.

METHODS Adults with ≥1 diagnostic claim were identified from Symphony Health’s Integrated Dataverse® (January 1, 2014 - December 31, 2019)of pharmaceutical and medical claims. Twelve-month costs were evaluated from an index date (first claim from 2018 to 2019), and included gMG therapies such as acetylcholinesterase inhibitors, corticosteroids, NSISTs, immune-globulins, rituximab and eculizumab. Costs were also assessed three years before, during, and one-year following crisis. A systematic literature review and clinical expert interviews informed and validated the study design.

RESULTS Of the overall population (N=42 114), 12 884 (30.6%) and 240 (0.57%) were identified as newly diagnosed (incident) and crisis subgroups, respectively. Incident patients incurred higher mean costs compared to non-incident patients ($28 414 vs $17 270) and were more likely to receive steroids (61.8% vs 54.1%) and acetylcholinesterase inhibitors (72.6% vs 65.6%). While few incident (11.3%) and non-incident (11.7%) patients received immune globulins, these therapies formed 77.1% and 79.6% of mean gMG drug costs. Costs were higher 12 months prior to a crisis compared to 12 to 36 months prior. The 12-month period following a crisis event was also associated with high costs.

CONCLUSIONS Beyond costs associated directly with crisis, use of immune-globulins, newly diagnosed status and the year prior to and following a crisis are a significant contributor to direct costs in adults with gMG in the US.