Bidirectional Association of Rheumatoid Arthritis and Irritable Bowel Syndrome: A Large-Scale Prospective Cohort Study.

Abstract

To investigate the bidirectional prospective association between rheumatoid arthritis (RA) and irritable bowel syndrome (IBS) in a large-scale, long-term population-based cohort. Participants without any cancer at baseline were included between 2006 and 2010. Overall, 5455 prevalent RA cases and 419,670 non-RA participants in cohort 1 were included to examine the risk of incident IBS, and 22,126 prevalent IBS cases and 419,670 non-IBS participants in cohort 2 were included to assess the risk of incident RA. A multivariable Cox proportional hazards model was employed to estimate adjusted hazard ratio. Overall, 8984 new IBS cases were identified in cohort 1 during a total of 5,980,083 person-years of follow-up. After adjustment for multiple confounders, RA patients exhibited a 1.30-fold increased risk (95% CI, 1.12 to 1.51) for development of IBS, with an even 1.4-fold higher risk in those with RA duration of 10 years or more. By contrast, a total of 5777 incident RA cases were identified during a median follow-up of 14.3 years in cohort 2. Patients with IBS demonstrated a 1.53-fold increased risk (95% CI, 1.39 to 1.68) for development of RA. Sensitivity and subgroup analyses yielded similar results. The findings indicate that RA is associated with an increased risk for development of IBS, and conversely, IBS is associated with an increased risk for development of RA. Further research is necessary to confirm these findings and to elucidate the underlying biologic mechanisms.