title: Increased incidence of rheumatoid arthritis in multiple sclerosis: A nationwide cohort study.
abstract: Past studies have shown inconsistent results on whether there is an association between multiple sclerosis (MS) and rheumatoid arthritis. To investigate the possible relationship between the 2 autoimmune diseases, we performed a nationwide cohort study utilizing the National Health Insurance Research Database and the Registry of Catastrophic Illness.A total of 1456 newly diagnosed patients with MS and 10,362 control patients were matched for age, sex, and initial diagnosis date. Patients with MS had a higher incidence of rheumatoid arthritis (age-adjusted standardized incidence ratio: 1.72; 95% confidence interval = 1.01-2.91). There was a positive correlation in being diagnosed with rheumatoid arthritis in patients previously diagnosed with MS when stratified by sex and age. The strength of this association remained statistically significant after adjusting for sex, age, and smoking history (hazard ratio: 1.78, 95% confidence interval = 1.24-2.56, P = 0.002).In conclusion, this study demonstrates that a diagnosis of MS increased the likelihood of a subsequent diagnosis of rheumatoid arthritis in patients, independent of sex, age, and smoking history.
authors.affiliation: aDepartment of Internal Medicine, Kaohsiung Municipal Ta-Tung Hospital bDepartment of Kinesiology, Health and Leisure Studies, National University of Kaohsiung cDivision of Rheumatology, Department of Internal Medicine, Kaohsiung Medical University Hospital dGraduate Institute of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung eDivision of Endocrinology and Metabolism, Department of Internal Medicine, Changhua Christian Hospital, Changhua fGraduate Institute of Integrated Medicine, China Medical University, Taichung gInstitute of Biomedical Sciences, National Sun Yat-sen University, Kaohsiung, Taiwan.
authors.forename: Chia-Chun
authors.initials: CC
authors.lastname: Tseng
authors.forename: Shun-Jen
authors.initials: SJ
authors.lastname: Chang
authors.forename: Wen-Chan
authors.initials: WC
authors.lastname: Tsai
authors.forename: Tsan-Teng
authors.initials: TT
authors.lastname: Ou
authors.forename: Cheng-Chin
authors.initials: CC
authors.lastname: Wu
authors.forename: Wan-Yu
authors.initials: WY
authors.lastname: Sung
authors.forename: Ming-Chia
authors.initials: MC
authors.lastname: Hsieh
authors.forename: Jeng-Hsien
authors.initials: JH
authors.lastname: Yen
mesh_terms: D000328:Adult; D000368:Aged; D001172:Arthritis, Rheumatoid / Q000453:epidemiology* / Q000209:etiology*; D015331:Cohort Studies; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D009103:Multiple Sclerosis / Q000150:complications*; D012189:Retrospective Studies; D013624:Taiwan; D055815:Young Adult