A systematic review of 87 studies has found that patients with multiple sclerosis have a slightly increased mortality risk from COVID-19, notably those who are older with significant disability and/or comorbidities (Barzegar et al. Neurol Neuroimmunol Neuroinflamm 2021;8:e1001).
The analysis examined data for 4,310 MS patients with confirmed/suspected COVID-19. Mean age was 44.9 years, mean MS duration was 12.5 years; and mean EDSS score was 2.5. One-third had at least one comorbidity (primarily hypertension and diabetes). A total of 86.6% were receiving a disease-modifying therapy (DMT) at COVID onset. DMTs were B cell-depleting therapies (21.9%), interferon-β (11.9%), dimethyl fumarate (11.9%), fingolimod (9.4%), natalizumab (9.1%), teriflunomide (5.9%), glatiramer acetate (5.5%), cladribine (4.2%), and alemtuzumab (1.7%).
The most common COVID symptoms were fever (68.8%), cough (63.9%), fatigue/asthenia (51.2%), and dyspnea (39.5%). Anosmia and ageusia were reported by 16.2% and 10.6%, respectively.
The overall hospitalization rate was 20.7%. Risk factors for hospitalization were older age, progressive course and disability level. Hospitalization rates were highest in untreated MS patients (42.9%). Among treated patients, hospitalization was more common in those receiving a B cell-depleting agent (29.2%), teriflunomide (20.6%), and fingolimod (14.7%).
The overall mortality rate was 3.0%. This appears to be somewhat higher than the global mortality rate (2.2% at the time of the analysis; 2.1% as of 31 May). The case mortality rate in Canada and the U.S. is currently 1.8% (worldometer.com). The study did not report the age-adjusted mortality rate but noted that 19.1% of deaths were in MS patients < 50 years and 50.0% of deaths were in individuals aged >60 years.
The mortality rate was somewhat higher in patients receiving a B cell-depleting agent (2.5%) compared to other DMTs, such as teriflunomide (1.6%), natalizumab (1.1%), glatiramer acetate (0.8%) and fingolimod (0.5%). These differences may be due in part to the use of B cell-depleting agents in patients with greater disability or more severe disease. The mortality rate was highest in patients not receiving a DMT (8.4%), which likely reflects a patient population that is older or with more advanced disease.
The authors stated that MS may not increase the COVID-related mortality rate dramatically; a clearer picture should emerge when larger database studies are completed. They further noted that severe COVID may be overrepresented in current studies since they include only symptomatic patients; the proportion of MS patients with asymptomatic COVID-19 is unknown. Population-based studies are needed to better characterize COVID risks and outcomes.