Myasthenia Gravis (MG) Resource Utilization, Epidemiology, Survival, and Treatment Patterns (MG-REST): Estimating the Clinical and Economic Burden in Ontario, Canada.

OBJECTIVE

The study purpose was to quantify the epidemiology, healthcare resource utilization (HCRU), costs, survival, and treatment patterns of myasthenia gravis (MG) in Canada using population-based administrative data.

METHODS

A retrospective cohort study was conducted using administrative data in Ontario, Canada from 2013 to 2020. MG cases were identified using a validated algorithm. Outcomes included MG incidence and prevalence, myasthenic crisis incidence and prevalence, mortality, survival, HCRU, healthcare costs, and treatment patterns (among patients receiving public drug coverage; i.e., individuals ≥ 65 years).

RESULTS

The cohort included 2601 individuals with MG (mean age 65.7 years; 46.7% female). Standardized incidence remained stable (3.2-4.0 per 100,000), while prevalence increased from 36 to 42 per 100,000 from 2013/14 to 2019/20. Myasthenic crisis occurred in 8.9% of individuals over the study, with a post-diagnosis incidence rate of 2.6 per 100 person-years and 30-day mortality of 28.1%. 5-year overall survival was 75%, declining to 39% among those with crisis. Mean annual HCRU and direct costs were highest in the first-year post-diagnosis (10.0 specialists visits and CAD $31,693), decreasing in subsequent years. Mean crisis-related costs were CAD $32,948 per person-month in the first 90 days after crisis. During the study among patients ≥ 65 years, most (77.9%) received AChE inhibitors, and excluding AChE inhibitors, corticosteroids were the most common first-line treatment (62.7%).

CONCLUSIONS

MG imposes a substantial clinical and economic burden particularly among patients experiencing myasthenic crisis. These findings underscore the need for early intervention and improved access to advanced therapies to mitigate long-term morbidity and healthcare costs.