The association between bariatric surgery and incident rheumatoid arthritis

Objectives Obesity is considered a controversial risk factor for developing rheumatoid arthritis (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 January 1st, 2010 and December 31st, 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 December 31st, 2020. Incident RA was identified based on the relevant ICD-9 code (714). To further increase the specificity of the diagnosis, RA patients had to fulfill, additionally, one of the following : 1. RA diagnosis was made by rheumatologist, 2. Being positive for rheumatoid factor, or anti–cyclic citrullinated peptide, or 3. Purchasing at least one disease-modifying anti-rheumatic drug after RA diagnosis. Results Each group included 9583 patients. The mean follow-up period was 7.31 years. Among the 19166 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 increased risk for developing RA among patients with BMI > 40. Conclusions Bariatric surgery was not associated with reduced risk of incident RA during 10-year follow-up period.