Concomitant ankylosing spondylitis can increase the risk of biologics or small molecule therapies to control inflammatory bowel disease

BACKGROUND/AIMS: Patients with inflammatory bowel disease (IBD) are diagnosed with ankylosing spondylitis (AS) often. However, the disease course of patients with both IBD and AS is not well understood. This study aims to evaluate the effect of concomitant AS on IBD outcomes. METHODS: Among the 4,722 patients with IBD who were treated in 3 academic hospitals from 2004 to 2021, 55 were also diagnosed with AS (IBD-AS group). Based on patients’ electronic medical records, the outcomes of IBD in IBD-AS group and IBD group without AS (IBD-only group) were appraised. RESULTS: The proportion of patients treated with biologics or small molecule therapies was significantly higher in IBD-AS group than the proportion in IBD-only group (27.3% vs. 12.7%, P=0.036). Patients with both ulcerative colitis and AS had a significantly higher risk of biologics or small molecule therapies than patients with only ulcerative colitis (P<0.001). For univariable logistic regression, biologics or small molecule therapies were associated with concomitant AS (odds ratio, 4.099; 95% confidence interval, 1.863–9.021; P<0.001) and Crohn’s disease (odds ratio, 3.552; 95% confidence interval, 1.590–7.934; P=0.002). CONCLUSIONS: Concomitant AS is associated with the high possibility of biologics or small molecule therapies for IBD. IBD patients who also had AS may need more careful examination and active treatment to alleviate the severity of IBD.