Optimizing sampling device for the fecal immunochemical test increases colonoscopy yields in colorectal cancer screening

The fecal immunochemical test (FIT) that quantifies hemoglobin concentration is reported to be better than qualitative FIT and the reason for its superiority has not been interpreted. To evaluate and understand the superiority of quantitative FIT, a representative randomly selected population (n=2355) in Jiashan County, China, aged 40-74 years was invited for colorectal cancer screening in 2012. Three fecal samples were collected from each participant by one optimized and two common sampling devices, and then tested by both quantitative and qualitative FITs. Colonoscopy was provided independently to all participants. The performances of five featured screening strategies were compared. A total of 1020 participants were eligible. For screening advanced neoplasia, the positive predictive value (PPV) and the specificity of the strategy that tested one sample dissolved in an optimized device by quantitative FIT [PPV=40.8%, 95% confidence interval (CI): 27.1-54.6; specificity=96.8%, 95% CI: 95.7-98.0] were significantly improved over the strategy that tested one sample dissolved in the common device by qualitative FIT (PPV=14.1%, 95% CI: 8.2-19.9; specificity=87.9%, 95% CI: 85.8-89.9), whereas the sensitivity did not differ (39.2 and 37.3%, P=0.89). Similar disparity in performance was observed between the strategies using qualitative FIT to test one sample dissolved in optimized (PPV=29.5%, 95% CI: 18.1-41.0; specificity=95.3%, 95% CI: 94.0-96.7) versus common sampling devices. High sensitivity for advanced neoplasia was observed in the strategy that tested two samples by qualitative FIT (52.9%, 95% CI: 39.2-66.6). Quantitative FIT is better than qualitative FIT for screening advanced colorectal neoplasia. However, the fecal sampling device might contribute most significantly toward the superiority of quantitative FIT.