Key result
Initiation of low-dose aspirin was associated with an increased risk of lower gastrointestinal bleeding within 3 months compared to non-users (RR 2.79; 95% CI 2.40 to 3.24).
Why the study?
Aspirin may increase lower gastrointestinal bleeding from colorectal cancer precursors; the authors investigated whether low-dose aspirin use leads to colonoscopy and polypectomy before manifest colorectal cancer.
Does low-dose aspirin increase the risk of lower gastrointestinal bleeding and subsequent detection of colorectal neoplasms in a population without CRC screening?
Cohort (n=1,648,762)
Does low-dose aspirin increase the risk of lower gastrointestinal bleeding and subsequent detection of colorectal neoplasms in a population without CRC screening?
Relative Risk: 2.79 (95% CI 2.4–3.24)
Low-dose aspirin increases early lower gastrointestinal bleeding, which may expedite the detection and removal of premalignant polyps and reduce long-term colorectal cancer risk.
Aspirin initiation was associated with short-term increases in LGIB-driven endoscopy and polyp detection; leaves open a preventive mechanism for later CRC risk reduction.
OBJECTIVE: Aspirin may increase the risk of lower gastrointestinal bleeding (LGIB) from precursors of colorectal cancer (CRC). We investigated whether use of low-dose aspirin, through initiation of LGIB, may lead patients to undergo colonoscopy and polypectomy before manifest CRC. DESIGN: We conducted a historical cohort study (2005-2013) of all Danish residents who initiated low-dose aspirin treatment (n=412 202) in a setting without screening for CRC. Each new aspirin user was matched with three non-users (n=1 236 560) by age, sex and region of residence on the date of their matched new user's first-time aspirin prescription (index date). We computed absolute risks (ARs), risk differences and relative risks (RRs) of LGIB, lower gastrointestinal endoscopy, colorectal polyps and CRC, comparing aspirin users with non-users. RESULTS: The ARs were higher for new users than non-users for LGIB, lower gastrointestinal endoscopy, colorectal polyps and CRC within 3 months after index. Comparing new users with non-users, the RRs were 2.79 (95% CI 2.40 to 3.24) for LGIB, 1.73 (95% CI 1.63 to 1.84) for lower gastrointestinal endoscopy, 1.56 (95% CI 1.42 to 1.72) for colorectal polyps and 1.73 (95% CI 1.51 to 1.98) for CRC. The RRs remained elevated for more than 12 months after the index date, with the exception of CRC where the RRs were slightly decreased during the 3-5 years (RR 0.90, 95% CI 0.83 to 0.98) and more than 5 years (RR 0.91, 95% CI 0.82 to 1.00) following the index date. CONCLUSION: These findings indicate that aspirin may contribute to reduce CRC risk by causing premalignant polyps to bleed, thereby expediting colonoscopy and polypectomy before CRC development.
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Troelsen et al. (2020) conducted a cohort in Lower gastrointestinal bleeding and colorectal neoplasms (n=1,648,762). Low-dose aspirin vs. Non-users was evaluated on Lower gastrointestinal bleeding (LGIB) within 3 months (RR 2.79, 95% CI 2.40 to 3.24). Initiation of low-dose aspirin was associated with an increased risk of lower gastrointestinal bleeding within 3 months compared to non-users (RR 2.79; 95% CI 2.40 to 3.24).
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