Effect of anticoagulants and NSAIDs on accuracy of faecal immunochemical tests (FITs) in colorectal cancer screening: a systematic review and meta-analysis.

Objective: Most colorectal cancer (CRC) screening programmes are nowadays based on faecal immunochemical testing (FIT). Eligible subjects often use oral anticoagulants (OACs) or non-steroidal anti-inflammatory drugs (NSAIDs), which could possibly stimulate bleeding from both benign and premalignant lesions in the colon. The aim of this meta-analysis was to study the effect of OACs and NSAIDs use on FIT performance.

Design: A systematic search was conducted until June 2017 to retrieve studies from PubMed, Embase, MEDLINE, Web of science, Cochrane Central and Google Scholar. Studies were included when reporting on FIT results in users versus non-users of OACs and/or NSAIDs in average risk CRC screening populations. Primary outcome was positive predictive value for advanced neoplasia (PPV) of FIT in relation to OACs/NSAIDs use. Values were obtained by conducting random-effect forest plots.

Results: Our literature search identified 2022 records, of which 8 studies were included. A total of 3563 participants with a positive FIT were included. Use of OACs was associated with a PPV of 37.6% (95% CI 33.9 to 41.4) compared with 40.3% (95% CI 38.5 to 42.1) for non-users (p=0.75). Pooled PPV in aspirin/NSAID users was 38.2% (95% CI 33.8 to 42.9) compared with 39.4% (95% CI 37.5 to 41.3) for non-users (p=0.59).

Conclusion: FIT accuracy is not affected by OACs and aspirin/NSAIDs use. Based on the current literature, withdrawal of OACs or NSAIDs before FIT screening is not recommended. Future studies should focus on duration of use, dosage and classes of drugs in association with accuracy of FIT to conduct more specific guideline recommendations.