COVID-19 not linked to increased MS relapse rate: Meta-analysis

COVID-19 doesn’t appear to increase the likelihood of a relapse, where new symptoms suddenly appear or existing ones worsen, for people with multiple sclerosis (MS), according to a meta-analysis of more than a dozen studies.

The findings alleviate some of the concerns MS patients may have about developing COVID-19, but the study’s researchers cautioned that well-controlled studies are still needed to confirm the results and address the impact of other factors, such as treatment and disability levels.

The study, “The Effect of COVID-19 on Multiple Sclerosis Relapse: A Systematic Review and Meta-analysis,” was published in Multiple Sclerosis and Related Disorders.

It’s thought that infection with SARS-CoV-2 — the virus that causes COVID-19 — may trick the immune system into launching an attack against healthy cells in the brain and spinal cord, setting the stage for MS to develop.

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Reports have also suggested COVID-19 can accelerate disability progression, at least in the first months after an infection, but its impact on MS relapse rates remains controversial.

“There has been growing concern about the impact of COVID-19 on the clinical course of MS, [but] there is a lack of high-quality evidence to establish the relationship between COVID-19 and MS,” wrote researchers in Iran and Pakistan who combined data from 14 studies identified through a literature search to get a better idea about the effects of COVID-19 on MS relapses. All the studies were published from 2021 to 2023 and included adults with a diagnosis of MS.

The median Expanded Disability Status Scale (EDSS) score ranged from 0.5 to 4.5 across the studies, indicating no significant disability. The EDSS is a clinical tool that ranges from 0 to 10 points, with higher scores indicating worse disability.

The definition of a relapse varied across the studies, but most defined it as episodes of new or worsening symptoms that lasted at least 24 hours in the absence of fever or infection. The proportion of patients with COVID-19 who had a relapse was 7.71 per 100 people, or 7.71%.

Eight studies compared the rate of relapse between 1,003 patients with COVID-19 versus 1,667 people with MS who didn’t develop COVID-19. The relapse rate was not significantly different between the groups.

This observation held true regardless of age, sex, publication year, use of disease-modifying therapy, median EDSS, and length of hospital stay due to COVID-19.

Despite the small sample size, “the results of this systematic review and meta-analysis did not find any significant association between COVID-19 and MS relapse,” wrote the researchers, who noted “it is possible that different strains of COVID-19 may affect the risk of MS relapse to varying extents.”

More research is needed to show the impact of COVID-19, they said.