BACKGROUND
Ankylosing spondylitis (AS) and inflammatory bowel diseases (IBDs) have been reported to correlated with each other in retrospective studies.
OBJECTIVE
Through a large sample size of Prospective cohort study to further support the relationship between Ankylosing spondylitis and Inflammatory bowel disease.
METHODS
The prospective associations between AS and Crohn’s disease(CD) or between AS and ulcerative colitis(UC) were analyzed with Cox regression models in prospective study cohorts, using data from the UK Biobank. We also calculated a polygenic risk score(PRS) for AS and analyzed its association with the risk of CD or UC. Finally, we used two-sample Mendelian randomization(MR) analyses to determine whether AS and IBDs have causal relationships on each other.
RESULTS
Participants with AS were at an over 7.8-fold risk of developing CD, and a 3.5-fold risk of CD. Reversely, the risk of AS in participants with CD(HR, 6.03; 95% CI, 3.10 ~ 11.73; P< 0.001) or with UC(HR, 3.08; 95% CI, 1.58 ~ 5.98; P< 0.001) were also greatly higher than the control population. These risks remained similar after adjusting for confounding factors in multivariate Cox models. Higher PRS of AS was also significantly association with increased risk of CD(HR, 3.60; 95% CI, 1.81~7.18; P<0.001) or UC(HR, 3.12; 95% CI, 1.92~5.08; P<0.001). In addition, the Mendelian analysis suggested a causal relationship of CD or UC on AS.
CONCLUSIONS
AS and IBDs are associated with greatly increased risk of developing each other in the individual level. This bidirectional risk correlation should be of clinical attention.