Inflammatory Bowel Disease and Rheumatoid Arthritis Increase Each Other’s Risk, Study Confirms Long-Term Link
Researchers have found in a new study that patients with inflammatory bowel disease (IBD) have a dramatically higher risk of developing rheumatoid arthritis (RA), and vice versa, and established a bidirectional relationship between the two autoimmune diseases. The evidence comes from a large population-based cohort study with prolonged follow-up and offers strong evidence for a common mechanism of disease. The research highlights the requirement that clinicians screen for RA in IBD patients and for gastrointestinal symptoms in patients with RA because early diagnosis and treatment may enhance quality of life and long-term outcomes. The study was published in the journal of Rheumatology by Yijun Chen and colleagues.
Ulcerative colitis (UC) and Crohn's disease (CD), which together constitute inflammatory bowel disease, and rheumatoid arthritis are autoimmune inflammatory diseases that afflict millions worldwide. While the two diseases share systemic inflammation and immune dysregulation, the relationship between them has been obscure. Earlier case series and small studies had suggested potential associations, but strong prospective evidence of the risk that each disease bestows on the other has not been available. This research aimed to examine the long-term, two-way relationship between RA and IBD with data from two well-established, cancer-free population cohorts.
The research had two separate prospective cohorts. Cohort 1 consisted of 449,662 cancer-free participants at baseline, to estimate the risk of developing RA in individuals with a history of IBD. Cohort 2 involved 450,534 participants to estimate the risk of IBD in participants with baseline RA. The research excluded participants with a history of any cancer and had a median follow-up of 14.3 years in cohort 1 and 14.6 years in cohort 2.
The main outcomes were incident RA cases (in cohort 1) and incident IBD cases (in cohort 2), comprising UC and CD. Hazard ratios (HRs) and 95% confidence intervals (CIs) were estimated using Cox proportional hazard regression models, controlling for several confounding variables.
Results
Among 5,015 participants in cohort 1 with IBD at baseline, 6,001 (1.3%) developed RA during the follow-up period.
The research showed that individuals with IBD were at 44% increased risk of developing RA (HR = 1.44, 95% CI: 1.15–1.79) compared to individuals without IBD.
More specifically, individuals with ulcerative colitis were at 36% increased risk of developing RA (HR = 1.36, 95% CI: 1.06–1.75).
In cohort 2, 5,887 had RA at baseline. In the follow-up period, 2,988 participants (0.7%) developed IBD.
The findings revealed that RA patients were at 65% increased risk of developing IBD (HR = 1.65, 95% CI: 1.31–2.09).
This comprised a 60% increased risk for UC (HR = 1.60, 95% CI: 1.20–2.13) and a 65% increased risk for Crohn's disease (HR = 1.65, 95% CI: 1.12–2.42).
This study reinforces a robust, bidirectional relationship between IBD and RA. Individuals with IBD are at higher risk of developing RA and vice versa. These observations support common immune-mediated mechanisms and reaffirm the critical need for thorough monitoring of patients diagnosed with either of these diseases.
Reference:
Chen Y, Zhang Q, Liu S, Zhu S, Wu J, Zhang S, Li P, Wu S. Bidirectional association of rheumatoid arthritis and inflammatory bowel diseases: a large-scale prospective cohort study. Rheumatology (Oxford). 2025 Jun 13:keaf337. doi: 10.1093/rheumatology/keaf337. Epub ahead of print. PMID: 40511997.
