Introduction While NSAIDs can affect any part of the GI tract, little is known about the effect of aspirin in the small bowel or colon. In this prospective analysis, we compared upper GI, small bowel, and colonic findings in patients taking aspirin vs. those taking NSAIDs while being considered in the screening phase of the MASTERS Trial (Misoprostol for the Healing of Small Bowel Ulceration in Patients with Obscure Blood Loss while Taking Low-Dose Aspirin or Non-Steroidal Anti-inflammatory Drugs).

Method For MASTERS, obscure occult bleeding was defined as having absence of potentially bleeding lesions on colonoscopy and endoscopy, and in the presence of one or more of the following: positive faecal occult blood test; iron deficiency anaemia; or drop in Hb, > 2 gm/dl from baseline. Suitable patients underwent small bowel video capsule endoscopy (Omom systems, China).

Results DEMOGRAPHY: 127 patients were assessed: 80 taking aspirin alone without NSAIDs and 47 taking NSAIDs alone without aspirin; they all had colonoscopy while smaller numbers underwent upper GI or capsule endoscopy. The aspirin group had older patients (median 69 vs. 61 years, p<0.001) and more males (64% vs. 40%, p=0.016). UPPER GI ENDOSCOPY: In the aspirin group (n=56), 5% had oesophagitis, 4% peptic ulcers, 5% erosions, and 32% had other findings, compared with 5%, 11%, 8%, and 32%, respectively, in the NSAID group (n=38). SMALL BOWEL LESIONS: As shown in Table-1, no significant differences were seen between the users of aspirin or NSAIDs. COLONOSCOPY: In the aspirin group (n=80), 34% had diverticular disease, 5% cancer, and 8% had other disorders, compared with 34%, 2%, and 9%, respectively, in the NSAID group (n=47). However, the aspirin group had 33 patients (41%) with colonic polyps vs. 7 (15%) in the NSAID group, [unadjusted OR 4.0 (95% CI, 1.6–10.0), p=0.003]. This remained significant after adjusting for age and sex [OR 3.5 (95% CI, 1.3–9.3), p=0.012].

Conclusion (1) In this prospective analysis, patients with obscure occult bleeding and using aspirin have similar prevalence and range of lesions in the small bowel and upper GI tract as those using NSAIDs. (2) The use of NSAIDs was associated with fewer patients with colonic polyps. These results might help in planning and interpreting the investigations of obscure bleeding. They might also be relevant to colon cancer chemoprevention.

Disclosure of Interest None Declared