Factors associated with false fecal immunochemical test results in colorectal cancer screening

Certain subgroups are at an increased risk of false fecal immunochemical test (FIT) results; however, related studies are limited, and the available evidence is conflicting.

To evaluate factors associated with false-positive and false-negative FIT results.

This retrospective study was based on the database of the Tianjin Colorectal Cancer Screening Program from 2012 to 2020. A total of 4129947 residents aged 40-74 years completed at least one FIT. Of these, 24890 asymptomatic participants who underwent colonoscopy examinations and completed lifestyle questionnaires were included in the analysis. Multivariable logistic regression was performed to identify the factors associated with false FIT results.

Among the overall screening population, 88687 (2.15%) participants tested positive for FIT. The sensitivity, specificity, positive predictive value, and negative predictive value of FIT for advanced neoplasms were 58.2%, 44.8%, 9.7%, and 91.3%, respectively. Older age, female sex, smoking, alcohol consumption, higher body mass index, and hemorrhoids were significantly associated with increased odds of false-positive and lower odds of false-negative FIT results. Moreover, features of high-grade dysplasia or villous for advanced adenoma and the presence of cancer were also associated with lower odds of false-negative results, while irregular exercise and diverticulum were associated with higher odds of false-positive results.

FIT results may be inaccurate in certain subgroups. Our results provide important evidence for further individualization of screening strategies.