Improvements in colorectal cancer screening programmes - quantitative immunochemical faecal occult blood testing - how to set the cut-off for a particular population

Abstract

Objective. The aim of the study was to determine the optimum cut-off value of the quantitative immunochemical test (q-FIT) OC-Sensor® for colorectal cancer and advanced adenomatous polyps in a particular population. Methods. 815 patients were referred for colonoscopy and were offered two q-FIT examinations at two different colonoscopy centers. The patients were classified according to the colonoscopic findings. Test sensitivity, specificity, and accuracy were statistically evaluated using one test and two tests at the levels of 50, 75, 100, 125, and 150 ng/mL of faecal hemoglobin in those patients with advanced polyps and colorectal cancer. The optimum cut-off test level for clinically significant neoplasia was determined using one test. Results. The optimum cut-off value of q-FIT OC-Sensor ® for the detection of clinically significant neoplasia in our particular population was determined as 75 ng/mL using one test. This value provides an optimum proportion of 73% sensitivity (±95% CI 60.3% -83.4%) and 90% specificity (±95% CI 86.8% -92.8%), PPV and NPV were determined as 54.76% and 95.43% respectively. Conclusions. The first step in the implementation of q-FIT test in the screening program in our country is to determine the optimum cut-off level for a population, and to estimate the number of tests performed with respect to the optimum cost effectiveness and economical climate. Using one test, the optimum level of q-FIT OC-Sensor® in the Czech Republic was determined as 75 ng/mL. This study could serve as a model for further studies in other countries, where screening does not yet exist.

Conflicts between Clinical and Public Health Viewpoints: Colorectal Screening

“…Both quantitative and qualitative FITs have been developed. Qualitative tests require a visual interpretation of test results as positive or negative; quantitative FITs are analysed automatically, providing a value for the amount of haemoglobin found in the stool sample [35].…”

Laboratory screening markers in gastroenterology - state of the art

“…Recent analyses of the cost-effectiveness of qiFOBT were published by Dutch working groups 25,26 ; the optimal cut-off value was found to be 50 ng Hb/mL. It is notable that the identical value was selected for screening in the Czech Republic based on a pilot study with OC-Sensor 27 . Faecal immunochemical test results may be expressed as haemoglobin concentration in the sampling device buffer and, sometimes, albeit rarely, as haemoglobin concentration per mass of the faeces.…”

Sensitivity and Specificity of Community Fecal Immunotesting Screening for Colorectal Carcinoma in a High-Risk Canadian Population

“…[6][7][8][9][10] Fecal immunochemical testing also offers advantages to clinical laboratories, including the potential for automation, the ability to customize the cutoff level to define a positive test, and improved cost-effectiveness. [11][12][13][14][15][16] Finally, by eliminating patients who do not need a colonoscopy, a FIT screening program may be more cost-effective than colonoscopybased screening. 17 Despite the numerous reported advantages of FIT as a screening modality, there are few community-based program evaluations describing the test characteristics of FIT (eg, sensitivity, specificity, and positive predictive value [PPV]) and therefore no data on which to evaluate existing and planned screening programs in Canada.…”