Co-existent autoimmune diseases in people with multiple sclerosis and a review on choice of immunotherapy

Aims Coexisting autoimmune diseases in multiple sclerosis (MS) may influence disease-modifying therapy (DMT) choice, but Indian data remains limited. This study aims to determine the prevalence of co-existent autoimmune disorders in Indian MS patients and assess their impact on DMT selection.Material and methods This multicentre, cross-sectional observational study included 355 adults with MS evaluated across five Indian neuroimmunology clinics between 2016 and 2026. Comorbidity prevalence was compared against general-population estimates, and DMT utilization was compared between patients with and without autoimmune comorbidities.Results Fifty-nine patients (16.6%) had an autoimmune disorder, with hypothyroidism (5.9%), rheumatoid arthritis (RA; 2.0%), and type 1 diabetes mellitus (1.4%) being the most common. Prevalences of RA (2.0% vs 0.49%; p = 0.002) and inflammatory bowel disease (IBD; 0.8% vs 0.02%; p < 0.001) were significantly higher than population estimates. Comorbidities shifted treatment: Rituximab use was lower in the comorbidity group (49.2% vs 69.3%; p = 0.003); dimethyl fumarate (22.0% vs 1.4%; p < 0.001) and azathioprine (5.1% vs 0.7%; p = 0.004) were prescribed more frequently.Conclusions Autoimmune comorbidity occurred in about 1/6 Indian MS patients, with excess RA and IBD relative to population prevalence and an associated shift in DMT selection.