Newer MS therapies tied to heightened infection risk

Takeaway

• Patients with relapsing-remitting multiple sclerosis (MS) starting newer disease-modifying therapies had elevated risks for infections requiring hospitalization that varied by drug.

Why this matters

• Better understanding of these risks will help inform treatment decisions.

Key results

• Compared with crude infection incidence rate per 1000 person-years in general population (5.2), rate higher in patients receiving:
  • Interferon-β (Avonex, Betaseron, Extavia, Rebif) and glatiramer acetate (Copaxone) (8.9).
  • Fingolimod (Gilenya) (14.3).
  • Natalizumab (Tysabri) (11.4).
  • Rituximab (Rituxan) (19.7).
• When interferon-β and glatiramer acetate were comparator, adjusted risk significantly higher only for rituximab (HR, 1.70; 95% CI, 1.11-2.61).
• Relative to use with interferon-β and glatiramer acetate:
  • Use of antibiotics higher with natalizumab (HR, 1.15; 95% CI, 1.01-1.31), rituximab (HR, 1.23; 95% CI, 1.08-1.40).
  • Use of herpes antiviral drugs higher with fingolimod (HR, 1.82; 95% CI, 1.34-2.46), natalizumab (HR, 1.71; 95% CI, 1.27-2.32).

Study design

• Swedish 7-year nationwide retrospective cohort study:
  • 6421 patients with relapsing-remitting MS initiating study drug.
  • 42,645 age-, sex-matched MS-free individuals from general population.
• Main outcome: serious infections (those resulting in hospitalization).
• Funding: Patient-Centered Outcomes Research Institute; Swedish Foundation for MS Research.

Limitations

• Reliance on registry data.
• Minor infections missed.
• Lack of information on some confounders.