Increased Rate of Hospitalisation for COVID-19 Amongst Rituximab Treated Multiple Sclerosis Patients: A Study of the Swedish MS Registry

Abstract

Background: The primary objective of this study was to analyse the association between multiple sclerosis (MS) disease modifying therapy (DMT) exposure and subsequent hospitalisation in patients infected with COVID-19.Methods: Data were extracted on the 18th January 2021 from the Swedish MS Registry, which collates nationwide, prospectively-collected clinical, demographic and, from March 2020 onwards, Covid-19-related information (including diagnostics and need of health care including needs of hospitalization, intensive care and ventilation) among persons with MS. Associations between MS DMT exposure and COVID-19 hospitalisation were analysed using univariable and multivariable clustered logistic regression, where the models were clustered on the individual patients to control for patients contributing multiple COVID-19 episodes. Propensity score based inverse probability of treatment weighting (IPTW) approach was used to adjust for confounders.Findings: As of 18th January 2021, a total of 476 reported COVID-19 cases had been recorded in MS patients in the Swedish MS registry. Of these, 292 (61.3%) had confirmed COVID-19. The mean (SD) age at infection was 44.0 years (11.6). Of the 292 confirmed infections 68 (23.2%) required hospitalisation. A total of 49 of the 164 confirmed COVID-19 patients on rituximab at baseline (29.9%) required hospitalisation, compared to a rate of 12.7% for all other DMTs combined. Rituximab in confirmed COVID-19 patients was associated with 2.95 times the weighted odds of hospitalisation relative to treatment with any other alternate DMT combined (Odds Ratio 2.95; 95% CI 1.48-5.87). The risk of severe COVID-19 increased with duration of rituximab treatment with a yearly Odds Ratio of 1.24 (95% CI 1.04-1.48).Interpretation: Rituximab treatment, known to increase the risk of severe infections in general, also confers such a risk for MS patients with COVID-19, in comparison with other MS DMTs.Funding: This study was supported by the Swedish Research Council and the Swedish Brain Foundation.Declaration of Interest: TS has received compensation for serving on scientific advisory boards, honoraria for consultancy and funding for travel from Biogen Inc; speaker honoraria from NovartisLF declared no competing interestsKAM receives postdoctoral research funding from the Swedish Research Council for Health, Working Life and Welfare.AG has received research support from Novartis.JH has received honoraria for serving on advisory boards for Biogen, Celgene, Sanofi, Merck KGaA, Novartis and Sandoz and speaker’s fees from Biogen, Novartis, Merck KGaA, Teva and Sanofi. He has served as P.I. for projects, or received unrestricted research support from, Biogen, Celgene, Merck KGaA, Novartis, Roche and Sanofi. His MS research was funded by the Swedish Research Council and the Swedish Brain foundation.