Multiple sclerosis and concomitant rheumatologic diseases: prevalence and management

Multiple sclerosis (MS) is a chronic autoimmune demyelinating disease of the central nervous system that shares several immunological and genetic pathways with systemic autoimmune disorders. The clinical significance of rheumatologic autoantibody positivity and its impact on treatment decisions in MS remains unclear.

This study aimed to determine the prevalence of rheumatologic autoantibody positivity and confirmed rheumatologic diseases in MS patients, evaluate the progression from isolated autoantibody positivity to clinically defined rheumatologic disease, and compare treatment patterns between patients with MS and concomitant rheumatologic disease (MS-Plus) and those with isolated MS.

In this hybrid retrospective-prospective study, patients diagnosed with MS according to the 2017 McDonald criteria and followed at a tertiary MS center between October 2021 and August 2026 were evaluated. Demographic, clinical, and laboratory data, including rheumatologic autoantibody profiles, were collected. Patients were categorized as MS-Plus, isolated MS, or asymptomatic autoantibody-positive. Disease-modifying therapies (DMTs) were classified according to efficacy level.

Among 588 MS patients, 54 (9.2%) had concomitant rheumatologic disease, most commonly Sjögren syndrome (25.9%). ANA positivity was the most frequently detected autoantibody (9.1%). Only three patients with isolated autoantibody positivity developed a rheumatologic disease during follow-up. High-efficacy DMT use was significantly lower in MS-Plus patients compared with isolated MS (22.2%vs. 42.3%, p = 0.005).

Rheumatologic comorbidity is not uncommon in MS and may influence therapeutic decision-making. Although autoantibody positivity is relatively frequent, progression to overt rheumatologic disease appears rare.