Objective: To identify clinical factors associated with a positive immunochemical fecal occult blood test [iFOBT] followed by a negative colonoscopic finding in a colorectal cancer [CRC] screening program.

Materials and Methods: A retrospective study was performed of data collected from a CRC screening program in 2013. Participants were aged 50 to 65 years, with no previous history of colonoscopy.
Their stool occult blood was tested at 0, 3, and 6 months, and if there was a positive result they underwent colonoscopy.

Results: There were 1,827 participants, among whom 379 cases had a positive iFOBT. The 356 cases that had complete data included 116 men (32.58%) and 240 women (67.42%). Their mean age was
57.56+4.38 years. In multivariate analysis, factors associated with a positive iFOBT and a negative colonoscopic finding were adjusted by sex, age, abnormal signs, and CRC family history. The presence of anemia was significantly associated with a positive iFOBT and a negative colonoscopic finding (adjusted OR, 1.44; 95% CI, 1.05 to 1.99; p = 0.026).

Conclusion: In patients with anemia who have a positive iFOBT and a negative colonoscopic finding, the physician should attempt to find possible causes of the unexplained anemia.

Keywords: Positive immunochemical fecal occult blood test, Negative colonoscopic finding, Hemorrhoids, Anemia