Does stool collection method affect outcomes in immunochemical fecal occult blood testing?

PURPOSE:This paper compares the positive predictive value of an immunochemical fecal occult blood test for colorectal neoplasms between the stool specimens obtained during the digital rectal examination and those obtained during the routine screening. METHODS:In a medical check-up, 1,688 subjects received both an immunochemical fecal occult blood test and a colonoscopy. Fecal occult blood was tested by two methodsdigital rectal examination and routine screening. The positivity rate of an immunochemical fecal occult blood test and the positive predictive value for colorectal cancer and large adenomatous polyp were determined by these two methods. RESULTS:The positivity rate and the positive predictive value were 5.4 percent and 19.8 percent (4.4 percent for cancer and 15.4 percent for adenomatous polyp) in the digital rectal examination method and 3.5 percent and 27.1 percent (6.8 percent for cancer and 20.3 percent for adenomatous polyp) in the routine screening method, respectively. These figures indicate a significant difference in the positivity rate (P