Rate of critical illness neuromyopathy during the first wave of COVID-19 pandemic: A single center retrospective study

Background and aims: The COVID-19 pandemic challenges neurologists in counseling patients with multiple sclerosis (pwMS) regarding SARS-CoV-2 risk and in guiding diseasemodifying treatments (DMT). We aimed to characterize overall mortality and severity of COVID-19 in pwMS and specifically associated with DMT. Methods: We included pwMS aged 18 years with a confirmed diagnosis of COVID-19 established between January 1, 2020 and December 31, 2020. COVID-19 course was classified as either mild, severe or fatal. Impact of overall and immunosuppressive DMT (alemtuzumab, cladribine, fingolimod, ocrelizumab or rituximab) on probability of severe or fatal COVID-19 was determined by multivariable models, adjusted for a-priori-risk estimated by a recently developed score (comprising age, comorbidities, and degree of disability). Results: Of 73 MS patients with COVID-19 (mean age: 41.4 years [SD 13.3], 65% female), 87.5% had a mild course, 9.7% a severe course and 2.8% died from COVID-19. A-priori-risk significantly predicted COVID-19 severity (R2 0.862;p<0.001) and mortality (R2 0.663;p<0.001). Adjusting for a-priori-risk, neither DMT exposure was significantly associated with COVID- 19 severity (OR: 1.6;CI: 0.2-11.9;p=0.667) or mortality (OR: 0.5;CI: 0.2-19.6;p=0.711), nor exposure to specific immunosuppressive DMT (ORs severity and mortality: 1.9 and 2.1;p=0.426 and p=0.233, respectively). Conclusion: In a population-based MS cohort, COVID-19 severity and mortality were independent of DMT exposure and immunosuppressive DMT after accounting for unmodifiable risk factors. This provides reassuring evidence that COVID-19 risk can be anticipated in MS and - except for a small proportion of high-risk patients - treatment decisions should be focused on treating MS rather than the pandemic.