Increased Risk of Autoimmune Diseases over Time prior to Multiple Sclerosis and Neuromyelitis Optica Spectrum Disorder Onset: A Nationwide Population Cohort Study in South Korea

초록

Introduction: Multiple sclerosis (MS) and neuromyelitis optica spectrum disorder (NMOSD) are autoimmune diseases of the central nervous system and are frequently reported in patients with other autoimmune diseases. However, the relative risk of autoimmune diseases prior to the onset of MS over time has not been well reported. Objectives/Aims: We aimed to elucidate the temporal association of autoimmune diseases before the diagnosis of MS/NMOSD. Methods: MS (n = 3,019) and NMOSD (n = 1,391) cohorts were collected from the Korean National Health Insurance Service between 1 January 2011 and 31 December 2021, using the International Classification of Diseases, 10th revision, diagnostic codes and information from the Rare Intractable Disease program. Ten age- and sex-matched controls were selected for each MS/NMOSD case. The risk ratios (RRs) of autoimmune diseases in MS/NMOSD were calculated compared with controls for 10 years prior to diagnosis. Autoimmune diseases included psoriasis, type I diabetes mellitus, rheumatoid arthritis (RA), systemic lupus erythematosus (SLE), uveitis, thyroiditis, asthma, and inflammatory bowel disease. Results: Approximately 39.5% of the MS cohort and 28.0% of the NMOSD cohort were under the age of 40, and 37.6% in the MS cohort and 27.4% in the NMOSD cohort were female. The RR of autoimmune diseases in the 10 years prior to diagnosis was 1.79 (95% confidence interval [CI] 1.66–1.92) in MS and 1.39 (95% CI 1.24–1.55) in NMOSD. The autoimmune diseases with the highest RRs were Crohn's disease in MS and SLE in NMOSD. The RR of total autoimmune diseases increased closer to the index date and was highest in the year before diagnosis. In the year before diagnosis, the autoimmune diseases with the highest RRs were rheumatoid arthritis in MS and SLE in NMOSD. Conclusion: Autoimmune diseases are more common in patients with MS/NMOSD than in controls before MS/NMOSD diagnosis, especially closer to the onset of MS/NMOSD.