Undergoing bariatric surgery does not appear to mitigate the risk of rheumatoid arthritis (RA) among individuals with obesity, as reported in a recent study.

The study used data from the SOS study and included 2,002 participants with obesity who underwent bariatric surgery and 2,034 matched controls who were free of RA at baseline. Compared with controls, participants who underwent surgery had higher body mass index (BMI), C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR), and were slightly younger and more likely to be smokers.

Bariatric surgery produced a sustained reduction in BMI (–23 percent at the 2-year follow-up; −17 percent at the 10-year follow-up). On the other hand, the control group showed a minimal increase in BMI (0.1 percent at the 2-year follow-up; 1.7 percent at the 10-year follow-up). Ninety-two participants developed RA over a median follow-up of 21 years.

On Cox analysis, bariatric surgery showed no association with RA incidence both in the intention-to-treat population (hazard ratio [HR], 0.92, 95 percent CI, 0.59–1.46; p=0.74) and in the per-protocol analysis (HR, 0.86, 0.54–1.38; p=0.53). The per-protocol analysis excluded participants from the control group who underwent bariatric surgery later on during follow-up.

Weight change at the 2-year follow-up, expressed as the change from baseline in BMI, was not associated with the development of RA. On the other hand, higher serum CRP levels and smoking contributed to an increased risk of developing RA, independent of other factors.

Obesity is a known risk factor for RA, and the condition negatively affects disease activity and treatment outcomes, researchers said. However, the present data with 29 years of follow-up indicate that weight loss via bariatric surgery confers no benefit for the incidence of RA.