Prevalence and characteristics of MS patients with COVID-19 infection at Karolinska University Hospital, Stockholm, Sweden

ABSTRACT

Introduction: Multiple sclerosis (MS), an immune-mediated neurodegenerative disorder, is commonly treated with diseasemodifying therapies (DMTs). DMTs affect the immune system, and some are associated with an increased risk of infections, potentially rendering MS patients vulnerable during the COVID- 19 pandemic. Objectives/aims: To determine the proportion of MS patients followed at Karolinska University Hospital (KS) that tested positive with COVID-19 between September 1st 2019, and September 1st 2021, determining proportion of MS patients that tested positive with COVID-19 depending on MS treatment, and estimating risk of contracting COVID-19 and risk of severe COVID-19 illness (hospitalization), depending on MS treatment. Method(s) A retrospective chart review was performed of all living MS-patients included in the Swedish MS registry and cared for at KS. Clinicodemographic, DMT and COVID-19 variables were recorded. DMTs were pooled into first-line (teriflunomide, interferons, glatiramer, fingolimod, siponimod and dimethylfumarate) and second-line (natalizumab, cladribine, ocrelizumab and haematopoietic stem cell transplantation) treatments. Rituximab was analysed seperately. Risk of contracting COVID-19 and risk of severe illness (hospitalization) was analysed with Chi-squared test. P-values of <0.05 were considered significant. P-values were adjusted according to Holm. Statistical analyses were performed using R version 4.1.1. Result(s) Of 1120 patients, 177 COVID-19 infections were identified (15.8%). Among treatments, rituximab accounted for the greatest proportion of infections (n=74, 41.8%), followed by no treatment (n=39, 22%) and dimethylfumarate (n=22, 12.4%). Compared to no treatment, rituximab (RR=3,36;95% CI 2.34- 4.83, p=0.001,padj = 0.001), pooled first-line treatments (RR=3.55;95% CI 2.43-5.20,p=<0.001,padj=<0.001) and second-line treatments (RR=2.65;95% CI 1.43-4.88,p=0.002,padj=0.013) were associated with increased risk of contracting COVID-19. Rituximab was also associated with an increased risk of hospitalization (RR=2.29;95% CI 1.03-5.13,p=0.037,padj= 0.112), although non-significant after adjustment. Conclusion(s) This project confirms reports of an increased susceptibility for COVID-19 while treated with common DMTs, as well as an increased risk of hospitalization while treated with rituximab. However, some results are not significant after adjustment and should be interpreted with caution.