ABSTRACT
BACKGROUND AND OBJECTIVES: Large-scale observational studies have shown that, in patients with multiple sclerosis (MS), the risk of becoming more severely ill from coronavirus disease 2019 (COVID-19) is determined by older age, male sex, cardiovascular comorbidities, African American ethnicity, progressive disease, recent use of corticosteroids, and B cell-depleting disease-modifying treatment. In contrast, the effect of COVID-19 on the disease course of MS has been studied much less extensively. Our main goal was to explore whether COVID-19 is associated with accelerated clinical disability worsening in patients with MS. METHODS: Since March 2020, demographics and infectious outcome (categorized as ambulatory, hospitalized, and/or death) of patients with MS who developed COVID-19 have been collected at the Belgian National MS Center in Melsbroek. On February 28, 2022, this database was locked and complemented with clinical disability measures-Expanded Disability Status Scale (EDSS), Timed 25-Foot Walk Test (T25FWT), 9-Hole Peg Test (9HPT), and Symbol Digit Modalities Test (SDMT)-that were available from a larger local database, obtained during routine medical follow-up. For each parameter, the first 2 assessments before COVID-19 diagnosis (T0 and T1; T1 is the closest to COVID-19 diagnosis), and the first thereafter (T2), were retrieved. RESULTS: We identified 234 unique cases of COVID-19. Thirty-one patients were hospitalized (13.2%), and 5 died (2.1%) as a result of their infection. Among survivors with complete EDSS results (N = 138), mean annualized T1-to-T2 EDSS worsening was more pronounced, compared with the respective change between T0 and T1 (0.3 ± 0.9 vs 0.1 ± 0.9, p = 0.012). No such differences were found for the T25FWT, 9HPT, and SDMT scores. Severe COVID-19 (hospitalization) was associated with clinically relevant T1-to-T2 EDSS worsening (OR 2.65, p = 0.042). Vaccination coverage in the total cohort was 53.8%. Being unprotected by vaccination at the time of infection was associated with a worse COVID-19 outcome (hospitalization and/or death; OR 3.52, p = 0.002) but not with clinically relevant T1-to-T2 EDSS worsening. DISCUSSION: The occurrence and severity of COVID-19 are both associated with clinical disability worsening in patients with MS. Vaccination protects against a more severe course of COVID-19 in this specific population. TRIAL REGISTRATION INFORMATION: The study has been registered at ClinicalTrials.gov (study registration number: NCT05403463).