In the Danish screening programme, the iFOBT is analysed on OC-Sensor DIANA (Eiken Chemical Company, Ltd, Japan). In the CDR, the analysis is performed at the Department of Clinical Biochemistry at the Regional Hospital of Randers. All iFOBTs requested from general practice during the study period will be analysed using this existing infrastructure in parallel with the screening samples. iFOBTs are analysed continuously and done by staff blinded to colonoscopic findings.
Studies of iFOBT cut-off values have primarily been conducted in a screening setting [45 (link)–49 ]. The cut-off value in the Danish screening programme is set to 100 μg/L. To our knowledge, no studies have investigated an optimal cut-off value for patients presenting non-alarm symptoms of CRC. Small amounts of blood loss in faeces are normal, but no exact reference level exists [50 (link)]. On the other hand, small amounts of blood in faeces may also be indicative of CRC. A low cut-off value for blood in stools increases the number of false positive test results and consequently the number of performed colonoscopies and required resources, whereas a high cut-off increases false negative test results and thereby introduces a risk of delay in the diagnosis [31 (link), 51 (link)]. In this study, we set the cut-off value to 50 μg/L. Thus, a value of <50 μg/L will be considered as negative and ≥50 μg/L as positive.
Studies of iFOBT cut-off values have primarily been conducted in a screening setting [45 (link)–49 ]. The cut-off value in the Danish screening programme is set to 100 μg/L. To our knowledge, no studies have investigated an optimal cut-off value for patients presenting non-alarm symptoms of CRC. Small amounts of blood loss in faeces are normal, but no exact reference level exists [50 (link)]. On the other hand, small amounts of blood in faeces may also be indicative of CRC. A low cut-off value for blood in stools increases the number of false positive test results and consequently the number of performed colonoscopies and required resources, whereas a high cut-off increases false negative test results and thereby introduces a risk of delay in the diagnosis [31 (link), 51 (link)]. In this study, we set the cut-off value to 50 μg/L. Thus, a value of <50 μg/L will be considered as negative and ≥50 μg/L as positive.
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