Background: The diagnosis of inflammatory bowel disease (IBD) is usually made in a symptomatic phase, when bowel damage has already started. Some early findings can be detected even years before the onset of first symptoms. Our study has focused on the new diagnosis of IBD in an asymptomatic population undergoing an endoscopic investigation.
Methods: We reviewed the database of our colorectal cancer screening programme. All patients were first assessed with faecal immunochemical test (FIT; OC-Sensor, Eiken Chemical Co., Tokyo, Japan) and, if this test was positive (cut-off 100 ng Hg/mL buffer), a colonoscopy was indicated. In this study we included all patients with a suspicion of IBD by endoscopy and further confirmed by means of histology. The study protocol was approved by the ethics committee of Euskadi. The primary aim of the study was to determine and characterize the incidental cases of new-onset IBD during routine screening colonoscopies.
Results: A total of 498.227 FIT were done in 11 hospitals (67% participation). In 31.005 of these cases a colonoscopy was performed (98% complete). We found 121 patients newly-diagnosed of IBD [58% male, age 57 years (SD 6.04), 62% ex or never smokers]: 87 ulcerative colitis (E1 in 30 cases, E2 in 28 and E3 in 29), 26 Crohn's disease (ileum in 12 patients, colon in 9 and ileocolonic in 5) and 8 IBD-U. FIT levels at diagnosis were comparable between all IBD subtypes. Only one patient associated perianal disease (anal fissure), and three patients had extraintestinal manifestations. Up to 24–38% of UC showed an atypical endoscopic appearance. UCEIS at diagnosis was 5 (4–6). We found no correlation between FIT value and UCEIS or histological activity at first presentation. At least one follow – up visit was available in 85% of the cohort. Median follow-up was 24 months (IQR 9–41). Between those subjects who were asymptomatic at diagnosis, thirty-four patients (37%) developed symptoms during this period (mainly rectal bleeding, diarrhoea and rectal syndrome). These symptoms appeared after 3 months (IQR 0–11). Those patients who developed symptoms were more likely to have higher levels of FIT at diagnosis [1096 pg Hb/g (230–2815) vs 429 pg Hg/g (215–1309)]. Treatment was prescribed in most cases (83%): mesalazine in 77%, steroids in 18%, thiopurines in 6%, 1 with methotrexate and 1 with leukapheresis. Two patients required anti-TNF biologics. Two subjects underwent surgery.
Conclusions: We found a 0.39% of new diagnosis of IBD during the colorectal cancer screening programme. Most of the cases were diagnosed of ulcerative colitis. More than a third of patients developed symptomatic disease (37%). Higher levels of FIT at diagnosis showed a higher probability of developing symptoms during the follow-up.