The association between bariatric surgery and incident rheumatoid arthritis.

Objectives: Obesity is considered a controversial risk factor for developing RA and the association between weight change and RA incidence is inconclusive. The aim of our study was to investigate the effect of weight loss after bariatric surgery on the incidence of RA. Methods: This retrospective cohort study included all patients who underwent bariatric surgery between 1 January 2010 and 31 December 2015 as documented in the Maccabi Healthcare Services (MHS) database. These patients were matched with a control group based on age and sex. The two groups were followed until the earliest of the following: incident RA, leaving MHS, death or end of follow-up by 31 December 2020. Incident RA was identified based on the relevant International Classification of Diseases, Ninth Revision code (714). To further increase the specificity of the diagnosis, RA patients had to additionally fulfil one of the following: RA diagnosis was made by a rheumatologist, being positive for RF or anti-CCP or purchasing at least one DMARD after an RA diagnosis. Results: Each group included 9583 patients. The mean follow-up period was 7.31 years. Among the 19 166 subjects, 18 incident RA cases were diagnosed, 9 in each group. The mean age of the patients who developed RA was 49.89 years and half of the patients were males. Male gender was associated with an increased risk for developing RA among patients with a BMI >40. Conclusion: Bariatric surgery was not associated with a reduced risk of incident RA during the 10-year follow-up period.