Abstract Details

B-cell depleting medications (e.g. rituximab, ocrelizumab) are highly effective for treating MS and other autoimmune neurologic diseases, leading to increasing long-term use of these medications. Patients treated with these medications are at increased risk of infection compared to healthy individuals, and this risk may increase with longer duration of treatment. Most studies investigating infection risk were conducted during the first 2 years of therapy and there is little data on patients receiving therapy for over 2 years.

To explore rates of minor and severe infections among patients with multiple sclerosis (MS) on long-term B-cell depleting therapy and to determine clinical factors associated with an increased risk of infection. 

In this retrospective, single-center observational study, patients with MS, neuromyelitis optica, and other autoimmune neurologic diseases treated with rituximab or ocrelizumab for ≥2 years from 2013 to 2021 were identified via systematic chart review. Demographic characteristics, laboratory values, infection diagnoses, antibiotic prescriptions, and infections requiring hospitalization were recorded across the duration of treatment. Logistic regression analyses were used to identify factors that increased the risk of infection and hospitalization. 

291 patients treated with B-cell depleting medications for ≥2 years were identified. Average duration of therapy at the time of analysis was 46 months. While on therapy, 55% of patients were diagnosed with an infection, 43% required antibiotic treatment, and 10% required hospitalization. Female sex, higher BMI, and longer duration of therapy were associated with increased risk of infection. Only longer duration of therapy was associated with increased risk of hospitalization. Annualized rates of infection and hospitalization were higher after 2 years of therapy compared to the first 2 years of therapy. 

Minor infections are common in patients with multiple sclerosis treated with B-cell depleting medications. Longer duration of therapy appears to be a risk factor for both minor and severe infections.