Cutoff value determines the performance of a semi-quantitative immunochemical faecal occult blood test in a colorectal cancer screening programme

Abstract

BACKGROUND:The cutoff of semi-quantitative immunochemical faecal occult blood tests (iFOBTs) influences colonoscopy referrals and detection rates. We studied the performance of an iFOBT (OC-Sensor) in colorectal cancer (CRC) screening at different cutoffs. METHODS: Dutch screening participants, 50 -75 years of age, with average CRC risk and an iFOBT value X50 ng ml À1 were offered colonoscopy. The detection rate was the percentage of participants with CRC or advanced adenomas (X10 mm, X20% villous, high-grade dysplasia). The number needed to scope (NNTScope) was the number of colonoscopies to be carried out to find one person with CRC or advanced adenomas. RESULTS: iFOBT values X50 ng ml À1 were detected in 526 of 6157 participants (8.5%) and 428 (81%) underwent colonoscopy. The detection rate for advanced lesions (28 CRC and 161 with advanced adenomas) was 3.1% (95% confidence interval: 2.6 -3.5%) and the NNTScope was 2.3. At 75 ng ml À1 , the detection rate was 2.7%, the NNTScope was 2.0 and the CRC miss rate compared with 50 ng ml À1 was o5% (N ¼ 1). At 100 ng ml À1 , the detection rate was 2.4% and the NNTScope was o2. Compared with 50 ng ml À1 , up to 200 ng ml À1 CRC miss rates remained at 16% (N ¼ 4). CONCLUSIONS: Cutoffs below the standard 100 ng ml À1 resulted in not only higher detection rates of advanced lesions but also more colonoscopies. With sufficient capacity, 75 ng ml À1 might be advised; if not, up to 200 ng ml À1 CRC miss rates are acceptable compared with the decrease in performed colonoscopies.

A new insight into fecal hemoglobin concentration‐dependent predictor for colorectal neoplasia

“…While the fecal immunochemical test (FIT) is widely used in population-based screening for colorectal neoplasia and is effective in reducing colorectal cancer mortality through early detection, [1][2][3][4][5][6][7][8][9][10][11][12] it has been not yet known whether the detailed information on quantitative fecal hemoglobin concentration (FHbC) available with the FIT might also be of use for predicting the risk of colorectal neoplasia. Unfortunately, because clinical practice is to select subjects with FHbC greater than a set cut-off for further clinical investigation the precise value of FHbC, although measured and often reported, is largely neglected.…”

Recommendations on screening for colorectal cancer in primary care

“…The systematic review compared FIT with gFOBT for population-based colorectal cancer screening. The review included two random comparisons, in which patients were assigned to either FIT or gFOBT, 23,24 and two other studies, in which all patients were assessed using both FIT and gFOBT. 25,26 Box 1: Grading of recommendations Recommendations are graded according to the Grading of Recommendations Assessment, Development and Evaluation (GRADE) system.…”

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

“…Considering economic aspects, we took advantage of q-FIT to achieve an increase in test sensitivity by decreasing the cut-off value and, with respect to specificity; we chose the best cut-off point using a q-FIT. The technology of q-FIT ensures ideal sensitivity/specificity ratio by virtue of the quantitative results [18][19][20][21] . The lower proportion of complete colonoscopies in our survey was due to the exclusion of patients with poor preparation who were not willing to undergo repeated colonoscopy within the specified time-frame.…”