A cohort study conducted in Sweden between spanning the year of 2017 has investigated the risk of serious infection associated with disease-modifying therapies for multiple sclerosis (MS), compared to injectable therapies interferon beta and glatiramer acetate (GA). In addition, the infection risk associated with off-label use of rituximab for MS treatment was examined. The study included 6,421 patients with relapsing-remitting MS (3,260 taking rituximab, 1,588 natalizumab, 1,535 fingolimod and 2,217 interferon beta/GA), with mean (SD) age ranging from 35 (10.1) – 40.4 (10.6) years at commencement of treatment. 42,645 individuals were included in a comparator cohort. The general population had the lowest crude rate of infections (incidence rate, 5.2 [95% CI, 4.8-5.5] per 1000 person-years). Higher incidence rates were observed in patients taking interferon beta/GA (incidence rate, 8.9 [95% CI, 6.4-12.1] per 1000 person-years), natalizumab (incidence rate, 11.4 [95% CI, 8.3-15.3] per 1000 person-years), fingolimod (incidence rate, 14.3 [95% CI, 10.8-18.5] per 1000 person-years) and rituximab (incidence rate, 19.7 [95% CI, 16.4-23.5] per 1000 person-years). Outpatient treatment with herpes antiviral medications was higher with natalizumab (HR, 1.82 [1.34-2.46]) and fingolimod (HR, 1.71 [95% CI, 1.27-2.32]) than during rituximab and interferon beta/GA treatment. It was concluded that the lowest rate of serious infection was associated with interferon beta/GA and the highest rate was observed with off-label rituximab use. The results generated from this study can be utilised to further improve risk-benefit assessments related to the various multiple sclerosis treatments available. The full paper can be viewed here.

Contributed by Australian Medication Safety Services Associate – Isabella Singh