Economic burden of myasthenia gravis in France: A nationwide claims database study (STAMINA).

Myasthenia gravis (MG) is a chronic autoimmune disease with symptoms of muscle weakness and fatigability. The aim of this study was to estimate MG-related healthcare resource use (HCRU), associated direct costs and their determinants in France. Data were extracted from the French national claims database (SNDS) for the period 1/1/2008-31/12/2019. Adult patients with MG were identified using an algorithm based primarily on the G70 ICD-10 code. The incident and prevalent MG populations were compared with matched non-MG controls and direct costs were estimated. An exploratory indirect cost analysis restricted to sick leave and disability was also performed and a multivariable model used to identify patients' characteristics associated with higher direct MG costs. In 2019, the mean annual direct cost per patient with MG was €8,506 compared with €3,670 in controls, leading to an MG-excess cost of €4,836 per patient. Patients with MG had significantly (p < 0.0001) higher HCRU than controls in all items of inpatient and outpatient care. MG-excess costs were high, especially in the first year after disease identification and were mainly driven by hospitalizationsfor crises and exacerbations. They remained relatively stable thereafter. Patients with MG were on sick leave more often and for longer periods and were 2-3 times more likely to receive disability or living allowance than controls. The highest costs were concentrated during the first year after MG identification due to exacerbations and crises requiring hospitalization with costly medications and procedures. Novel innovative treatments are expected to change these main drivers of medical costs.