Background/Purpose: The prevalence of concurrent Ankylosing spondylitis (AS) and inflammatory bowel disease, either Crohn’s disease (CD) or Ulcerative colitis (UC), is estimated at 5-10%. Up to 50% of patients with AS have subclinical gut inflammation seen on ileocolonoscopy. This study was purposed to evaluate the association between reasons for ileocolonoscopy and the ileocolonoscopic findings in the patients with AS.

Methods: The retrospective study has included 108 AS patients who had ileocolonoscopy at a single tertiary hospital from January 2000 to April 2014. Patients with a history of CD, UC, intestinal tuberculosis, or colon cancer were excluded. Patients were divided into two groups based on ileocolonoscopic results: 1) negative inflammatory lesions (including colon polyps, hemorrhoids and diverticulums) and 2) positive inflammatory lesions (including ulcers, erosion and inflammation). The clinical features including HLA-B27 profiles, inflammatory indices, and reasons for ileocolonoscopy including regular health checkup without symptoms (for screening), abdominal pain, rectal bleeding, diarrhea, constipation, anemia and positive stool occult blood were evaluated.

Results: As shown in Table, inflammatory lesions in ileocolonoscopic findings were found in 40 (37.0%) patients out of the 108 patients. Mean age was significantly lower in the group with inflammatory lesions than the group without inflammatory lesions (36.9 vs. 41.9 years, p=0.017). Mean ESR and mean CRP were significantly higher in the group with inflammatory lesions than the group without inflammatory lesions. Presence of symptoms or signs (n=34) was associated with risk of inflammatory ileocolonoscopic findings compared to for screening (n=6) (OR=3.96, 95% CI 1.46, 10.71, p=0.005). Among the patient’s symptoms or signs, abdominal pain (n=13) was associated with inflammatory ileocolonoscopic findings most importantly (vs. negative abdominal pain (n=20); OR=2.47, 95% CI 0.88, 6.99, p=0.087). Among 40 patients with inflammatory lesions, 12 as CD, 1 as UC, and 4 as intestinal tuberculosis were diagnosed finally. However, most of them, 23 patients were considered as subclinical gut inflammation.

Conclusion: Considerable proportion of AS patients showed inflammatory gut lesions, even in the patients without gastrointestinal symptoms. Moreover, abdominal pain increased a possibility of inflammatory gut lesions in AS patients. Therefore, regular checkup with ileocolonoscopy could be recommended in AS patients.

Table. Patient’s characteristics

ESR; erythrocyte segmentation rate, CRP; c-reactive protein