OBJECTIVES: Reliable real-world data on the burden of MG is needed to inform Canadian clinical and policy decisions in the era of new MG therapeutics, including FcRn inhibitors. Given the lack of recent Canadian data on MG burden of disease, the MG-REST Study estimated the economic burden of MG in Ontario, Canada.

METHODS: Health administrative data from Ontario held at ICES were utilized for a retrospective population-based cohort study of adults with MG identified through a validated algorithm (April 2013-March 2019) and followed up to March 2020 to determine healthcare resource utilization (HCRU) and direct healthcare costs ($CAD).

RESULTS: The MG cohort (n=2,601) had an average age of 65.7 years and 53.3% were males. The average number of specialist visits was 10.0, 7.3, and 6.3 per person-year, and the average total healthcare costs ($CAD) were $33,992, $19,688, and $16,506 per person-year, in year 1, 2, and 3 post-diagnosis, respectively.

A subgroup of patients (n=231; 9%) experienced their first myasthenic crisis (MC) during the study. In these patients, the average total direct healthcare costs ($CAD) were $40,484, $13,161, and $8,671 per person-month, in the first 3 months, 3-6 months, and 6-12 months post-first MC, respectively. In total, the average post-crisis cost was $212,961 per person-year.

CONCLUSIONS: Despite the availability of conventional therapies throughout the study, MG and complications of MG including MC, remain serious conditions, with high HCRU and costs. A strength of this study is the usage of provincial data that captures costs for all public healthcare services based on well-established costing methodology. A limitation is the unavailability of data on costly immunoglobulin therapy usage, leading to an underestimation of total costs. This study highlights the high economic burden of MG for the healthcare system with the existing MG therapies and the ongoing need to reduce this burden.