Autoimmune thyroiditis and its impact on the clinical course of Multiple Sclerosis: A retrospective cohort study

Introduction: Autoimmune thyroiditis (AT) stands out as one of the most prevalent accompanying comorbidity of Multiple Sclerosis (MS). However, the specific impact of AT on the clinical course of MS is relatively unexplored. Objectives: The primary objective of this study is to determine the frequency of AT within an MS cohort and to assess its influence on the prognosis of MS. Method: We retrospectively detected those who had an AT diagnosis during their lifetime. Patients who had been diagnosed with AT before a diagnosis of MS or during the diagnosis process were analyzed for prognosis. (aMS) Demographic variables, baseline Expanded Disability Status Scale (EDSS) score and relapse number, disease- modifying treatment duration and type, the relapse number, new/expanding lesions in brain and spinal MRI in first five years, fifth-year EDSS and fifth year No Evidence of Disease Activitiy-3 results were collected. These variables were compared to people with MS who had similar baseline and demographic characteristics. (non-AT) Results: Fifty-seven people with MS (1.6 %) were diagnosed with AT, all of whom were female. Twenty-four of them were included in the prognosis analysis. There was no statistical difference between aMS and nonAT in diagnosis age, baseline relapse number and baseline EDSS score. (p > 0.05) There were no statistical differences in relapse number, MRI activity in five years, EDSS scores and NEDA-3 status in the fifth year. (P > 0.05) Conclusion: Comorbid AT is frequently seen in the MS population. It has a neutral effect on the MS course.