Background: Fecal immunochemical test (FIT) is a yearly alternative colorectal screening modality for average risk individuals unwilling or unable to undergo invasive colorectal cancer (CRC) screening due to cost and accessibility. This study aims to determine whether FIT should be interpreted within the context of patient demographics and medical history.
Methods: Patients >50 years old who had a FIT followed by colonoscopy within 1 year were analyzed based on age, race, BMI, social and medical comorbidities. False positive (FP) and false negative (FN) FIT results within each patient demographic and medical history variable were determined by comparing with the gold standard of colonoscopy using Chi-square analysis.
Results: 1025 patients were reviewed. 21.8% of FIT results were positive. Factors which differed in positive FIT rates were age (p=0.003), smoking (p<0.001), alcohol (p=0.001), and hypertension (p<0.001). The difference in rates of FP and FN FIT outcomes among each variable underwent further sub-analysis. The FP was 66.8% and the FN rate was 12.8%. Higher FN outcomes were noted in those above 70, males and smokers, though the result was only statistically significant for males (p=0.009). Females were observed to have higher FP rates (p=0.019).
Conclusions: Females had higher FP FIT rates compared to males, indicating that sex may influence FIT outcomes and should be accounted for when interpreting FIT results. This information can be utilized to identify populations at higher risk of FP or FN FIT results to target CRC screening. Additionally, recalculating the FP and FN rates for each variable may help determine new FIT targets.