Effect of autoimmune comorbidities on multiple sclerosis course: An observational multicenter study

Background: The study aims to examine the age and disability levels at diagnosis in people with multiple sclerosis (PwMS), with and without autoimmune comorbidities (AC), and the effect of AC on NEDA-3 status and to characterize AC associated with MS, comparing also therapeutic approaches between MS patients with and without other AC. Methods: This population-based, multicentric study enrolled patients with relapsing–remitting MS (RRMS) with AC (AC group) or without AC (reference group) from 14 MS centers. Demographical, clinical features, treatment information, MRI activity, EDSS, and no evidence of disease activity (NEDA-3) status were assessed at T36 (enrollment time) and T0 (36 months prior). Results: Eight hundred seventy-three RRMS patients were included; 215 (24.7%) presented with at least one AC. The AC group was characterized by higher proportion of female patients than reference group (p = 0.008). Patients with AC, compared to reference group, exhibited older age at MS onset and MS diagnosis, and higher EDSS score at diagnosis, at T0 (all p < 0.001), and T36 (p = 0.03). The proportion of patients reaching EDSS 4 was higher in reference group than AC group (p = 0.03). People in AC group were more often treated with glatiramer acetate, natalizumab, and rituximab, whereas PwMS from reference group with interferon-beta and fingolimod at T0 and T36. The risk of losing NEDA-3 was lower in AC group (OR = 0.61, 95% CI 0.43–0.86, p = 0.005). Conclusions: AC are common in PwMS and can be related to a delay in onset, diagnosis and higher disability at MS presentation. However, the coexistence of AC is not associated with a worse prognosis.