Impact of Coronavirus Disease 2019 in a French Cohort of Myasthenia Gravis

Objective: To describe the clinical characteristics and outcomes of COVID-19 among patients with MG and identify factors associated with COVID-19 severity in MG patients.

Methods: The CO-MY-COVID registry was a multicenter, retrospective, observational cohort study conducted in neuromuscular referral centers and general hospitals of the FILNEMUS network (between March 1, 2020, and June 8, 2020), including MG patients with a confirmed or highly-suspected diagnosis of COVID-19. COVID-19 was diagnosed based on a polymerase chain reaction (PCR) test from a nasopharyngeal swab and/or SARS-CoV-2 serology, thoracic computed tomography (CT-scan), or typical symptoms. The main outcome was COVID-19 severity based on location of treatment/management (home, hospitalized in a medical unit, or in an intensive care unit). We collected information on demographic variables, general history, and risk factors for severe COVID-19. Multivariate ordinal regression models were used to identify factors associated with severe COVID-19 outcomes.

Results: Among 3,558 MG patients registered in the French database for rare disorders, 34 (0.96%) had COVID-19. The mean age at COVID-19 onset was 55.0 ±19.9 years (mean MG duration: 8.5 ± 8.5 years). By the end of the study period, 28 patients recovered from COVID-19, 1 remained affected, and 5 died. Only high Myasthenia Gravis Foundation of America (MGFA) class (≥IV) before COVID-19 was associated with severe COVID-19 (p=0.004); factors that were not associated included gender, MG duration, and medium MGFA classes (≤IIIb). The type of MG treatment had no independent effect on COVID-19 severity.

Conclusions: This registry-based cohort study shows that COVID-19 had a limited effect on most patients, and immunosuppressive medications and corticosteroids used for MG management are not risk factors for poorer outcomes. However, the risk of severe COVID-19 is elevated in patients with high MGFA classes [odds ratio: 102.6 (4.4; 2,371.9)]. These results are important for establishing evidence-based guidelines for the management of MG patients during the COVID-19 pandemic.