New research reveals that disability level, not just age, is a primary driver of serious infection risk for people with multiple sclerosis (MS), and that advanced therapies like anti-CD20 drugs double this risk compared to older treatments. The findings, from two separate studies, show that infections requiring hospitalization are common among MS patients, with urinary tract infections being the most frequent.
Disability Increases Infection Risk in MS Patients
Disability, even when mild, was strongly associated with the risk of serious infection in MS patients, according to a large real-world study led by Chloé Pierret, PhD. Another study found that patients with MS treated with rituximab, an anti-CD20 drug, had about twice the rate of infection requiring hospitalization compared with interferon and glatiramer acetate.
Anti-CD20 therapies were linked to a doubling of the risk of serious infection compared with interferon beta or glatiramer acetate, two established, lower-efficacy disease-modifying therapies (DMTs). In one cohort study, anti-CD20 drugs were associated with about 2.5 times the risk compared with alemtuzumab or mitoxantrone. The risk was not elevated with sphingosine-1-phosphate (S1P) receptor modulators, cladribine, or natalizumab.
Key Factors Identified
After adjustment, older age was not an independent risk factor once disability and comorbidities were considered. Comorbidities also increased the risk; the chance of serious infection rose by 40% to 90% for patients with respiratory disease, diabetes, chronic kidney disease, and bladder dysfunction. A second study confirmed that in multivariable analyses, treatment duration, EDSS scores, and the presence of comorbidity were independently associated with the risk of severe infections.
Even mild disability was a major risk factor.
Future Directions
Researchers plan to add laboratory markers, vaccination status, and cumulative dose exposure to future risk analyses. “We think that these factors should always be taken into account when assessing infection risk in MS,” said Pierret, an epidemiologist at the Multiple Sclerosis Centre of Catalonia. Another study noted that future research is needed to investigate strategies for mitigating infection risk, especially for older patients, those with higher levels of disability, and patients on longer-term treatment.
