Colorectal cancer (CRC) screening using fecal immunochemical tests (FIT) may reduce CRC-related mortality but its effectiveness is influenced by the limited accuracy of FIT. Identifying individuals at increased risk of a false FIT result could improve screening, but the available evidence is conflicting. We performed a systematic review and meta-analysis on risk factors for false-positive and false-negative FIT results in CRC screening.
A systematic search in MEDLINE, EMBASE, and Cochrane Library identified publications (before 29 January 2017) on risk factors (known at time of FIT invitation) associated with false FIT results (presence/absence of advanced neoplasia) in a CRC screening setting. Risk of bias was assessed using QUIPS. In meta-analysis, summary relative risk ratios and corresponding 95% confidence intervals were calculated for each risk factor.
Of 518 records identified, 14 studies with 54,499 participants in total were included for analysis. In meta-analysis, male sex was associated with a significantly lower risk of false-positivity (RR 0.84, CI 0.74-0.94), whereas participants using non-steroidal anti-inflammatory drugs (NSAIDs) had a higher risk (RR 1.16, CI 1.06-1.27). The use of anticoagulants was most frequently studied, without a significant effect on FIT positivity. Males (RR 1.83, CI 1.53-2.19), participants with a family history for CRC (RR 1.61, CI 1.19-2.15), hyperglycemia (RR 1.29, CI 1.02-1.65), hypertension (RR 1.50, CI 1.14-1.98), obesity (RR 1.38, CI 1.11-1.71), and (former) smokers (RR 1.93, CI 1.52-2.45) were all at significantly higher risk for false-negative results. Age was not found to have a systematic effect on either FIT false-positivity or false-negativity in meta-analysis.
Multiple risk factors, known at time of FIT invitation, are associated with false FIT results in CRC screening. This information can be used to identify populations risking false reassurance after a negative result or unnecessary colonoscopy after a positive result, and to further optimize CRC screening effectiveness.
1Department of Gastroenterology and Hepatology, Academic Medical Center, Amsterdam, The Netherlands. 2Department of Clinical Epidemiology, Biostatistics and Bioinformatics, Academic Medical Center, Amsterdam, The Netherlands.
Correspondence: E.D. (email: email@example.com)
Received 1 March 2018; accepted 29 June 2018; Published online 29 August 2018