Work

Immunoglobulin-G dynamics and relation to antibiotic prescriptions in multiple sclerosis patients treated with rituximab: a real-world cohort

Year: 2026

Type: article

Abstract: • Long-term rituximab treatment causes a significant, dose-dependent decline in IgG. • Cumulative dose is a stronger predictor of IgG decline than dose intensity. • Low IgG levels did not predict an increased risk of antibiotic prescriptions. • Female sex and higher disability at baseline predicted increased antibiotic use. • Routine IgG monitoring is warranted, especially in older patients with high exposure. Rituximab, a B-cell-depleting therapy widely used for multiple sclerosis (MS), is associated with a progressive decline in immunoglobulin G (IgG) levels, raising concerns regarding infection risk. This study evaluates IgG dynamics and antibiotic use in a real-world MS cohort. A retrospective cohort study was conducted on MS patients treated with Rituximab over a 10-year period. Patients included had at least two infusions and a follow-up of ≥6 months after the last infusion. IgG levels and antibiotic prescriptions were registered longitudinally. The study included 213 patients (72% female, mean age 40.1 ± 10.6 years). Mean IgG decreased from 11.5 ± 2.4 g/L at baseline to 9.0 ± 1.7 g/L after five years, with an average decline of 0.35 g/L/year (95% CI 0.25–0.44; p<0.001). Hypogammaglobulinemia (<6.7 g/L) occurred in 7.5% of patients. Cumulative rituximab dose was a significant predictor of lower IgG (p<0.001). Antibiotic prescriptions were recorded in 62% of patients (mean 2.5 per patient), most commonly for urinary (29%) and respiratory (17%) tract infections. In multivariable analysis, lower IgG levels did not significantly predict the risk of antibiotic prescription. Rituximab treatment resulted in a significant, dose-dependent IgG decline. However, this decline was not associated with an increased risk of antibiotic-treated infections, suggesting a dissociation between total IgG levels and functional immune competence in this cohort. These findings support continued use of rituximab with vigilant monitoring, though dose adjustments may be warranted for patients with rapidly decreasing IgG.

Source: Multiple Sclerosis and Related Disorders

DOI: 10.1016/j.msard.2026.106992

Authors: Niclas Lange, Elisabet Tina, Olof Hultgren, Anders Svenningsson, Martin Gunnarsson

Institutions: Örebro University, Danderyds sjukhus, Karolinska Institutet

Language: English

Topic: Multiple Sclerosis Research Studies

Subfield: Pathology and Forensic Medicine

Field: Medicine

Domain: Health Sciences

SDG: Good health and well-being

Open Access status: hybrid

Estimated APC paid: $3,500