The prevalence of autoimmune diseases in patients with multiple sclerosis: A cross-sectional study in Qom, Iran, in 2018

Background: Multiple sclerosis (MS) is one of the most common autoimmune diseases worldwide and various autoimmune comorbidities are reported with MS. The objective of this study is to estimate the prevalence of the autoimmune diseases’ comorbidity in patients with MS. Methods: In this cross-sectional study, we investigated a group of patients with MS in terms of age, gender, duration of MS, presence of simultaneous autoimmune diseases, such as Graves’ disease, Hashimoto’s thyroiditis, type 1 diabetes mellitus (DM), and systemic lupus erythematous (SLE). Results: This study included 1215 patients with MS, of which 70.8% were women. The mean age of participants was 33.70 ± 27.63 years. 55 patients (4.5%) had at least one autoimmune disease. The most common comorbidity was for Hashimoto’s thyroiditis (30 patients). The frequency of simultaneous autoimmune disease was higher in women. Mean age (P = 0.01), mean duration of MS (P = 0.03), and mean age on MS diagnosis (P = 0.02) were significantly higher in simultaneous MS and other autoimmune diseases. Conclusion: Our study revealed that the probability of autoimmune diseases co-occurrence in patients with MS could be higher in older patients, in longer duration of disease, and also in patients with higher age at time of MS diagnosis.