People with IBD Face Greater Risk of Spondyloarthritis, Study Suggests

3/13/2024

According to a recent study, people with inflammatory bowel disease (IBD) may face greater disease risk for types of spondyloarthritis (SpA), including ankylosing spondylitis, also known as radiographic axial spondyloarthritis (r-axSpA).

The study aimed to understand the relationship between IBD and different types of SpA. Researchers used a method called bidirectional two-sample Mendelian randomization (TSMR). TSMR is sometimes used as an alternative to randomized trials (which can be expensive and difficult to carry out) and observational studies (which can be affected by bias and causality errors). TSMR uses genetic variations to understand if a certain factor causes a specific health outcome. By studying how genes are inherited, researchers can get more reliable evidence about the impact of certain factors on our health.

In this case, researchers used TSMR to investigate the causal effects between IBD (specifically Crohn’s disease and ulcerative colitis) and common subtypes of SpA (including r-axSpA, psoriatic arthritis, and reactive arthritis).

The study found that there is a causal relationship between IBD and r-axSpA. Having IBD increases the risk of developing r-axSpA by about 28%. Specifically, Crohn’s disease increases the risk by about 20% and ulcerative colitis increases the risk by about 17%. IBD and its subtypes are also associated with an increased risk of other forms of SpA, such as psoriatic and reactive arthritis.

However, the reverse is not true. None of the subtypes of SpA were found to have a causal effect on any subtype of IBD. This one-way relationship has been observed in previous studies as well.

The exact cause of the link between IBD and SpA is still unclear, although scientists have proposed several possible explanations. One theory is that the disruption of gut microbes during IBD may activate immune cells that then migrate to the joints, causing inflammation. This is known as the “gut-joint axis.”

The study included only individuals of European descent, so the results may not apply to a broader population. Nonetheless, the researchers assert that their study highlights the importance of screening for SpA among people with IBD.

Resources:

• Gene – Mendelian randomization analysis reveals causal associations of inflammatory bowel disease with Spondyloarthritis
• SAA – Study Suggests Delayed Diagnosis of AS is Linked to Greater Incidence of Uveitis and IBD
• SAA – Predicting Crohn’s Disease in Those with Ankylosing Spondylitis