Risk Factors for False Fecal Immunochemical Test Results in Colorectal Cancer Screening

We investigated the factors associated with false fecal immunochemical test (FIT) results for advanced colorectal neoplasm (ACRN).

Data on whether certain subgroups of patients have an increased risk of inaccurate FIT results are extremely limited.

This was a retrospective study conducted in a university hospital in Korea from June 2013 to May 2015. Out of 34,547 participants who had an FIT completed, we analyzed a total of 3990 subjects aged 50 years and above who underwent colonoscopy.

The rates of false-negative and false-positive results were 58.0% and 15.7%, respectively. Elevated fasting blood glucose [adjusted odds ratio (AOR), 0.59; 95% confidence interval (CI), 0.36-0.97], the presence of high-grade dysplasia (AOR, 0.49; 95% CI, 0.25-0.95), 3 or more adenomas (AOR, 0.56; 95% CI, 0.35-0.89), cancer (AOR, 0.20; 95% CI, 0.11-0.38), and distal ACRN (AOR, 0.61; 95% CI, 0.39-0.96) were associated with a lower risk of false-negative FIT results. The presence of proximal ACRN (AOR, 1.59; 95% CI, 1.01-2.51) and adenoma ≥10 mm (AOR, 4.38; 95% CI, 2.17-8.87) were associated with a higher risk of false-negative results. Older age (70 y and above; AOR, 1.67; 95% CI, 1.29-2.17), diverticulum (AOR, 1.94; 95% CI, 1.45-2.58), and hemorrhoid (AOR, 1.63; 95% CI, 1.32-2.01) were associated with false-positive results.

Subjects with a higher risk of false-negative results should be prioritized for earlier colonoscopy and subjects with inaccurate results should be more cautiously considered for screening by using modalities other than FIT. Our findings will contribute to individualization of screening programs.