Oc sensor diana

The details of the method used for the FIT analysis have been described previously^{11 (link),18 (link)}. In brief, the patients prepared fecal samples using a Hemodia sampling probe (Eike Chemical, Tokyo, Japan). The submitted stool samples were immediately processed and examined using an OC-Sensor DIANA (Eiken Chemical) system, which can accurately measure fecal hemoglobin at concentrations of 50 to 1000 ng/mL. Fecal specimens with a hemoglobin concentration of > 1000 ng/mL were measured following dilution. Because FIT is not accurate for measuring hemoglobin concentrations of < 50 ng/mL, the specimens with a hemoglobin concentration within this range (0–50 ng/mL) were handled as category.

Sampling kits for stool sample collection are mailed to the participants three times during the study period, with the first sample being the positive BCSN FIT sample. No restrictions on diet or medication use are required prior to sampling. Stool is collected using plastic sticks, which collect about 10 mg stool. The stool is then stored in 2 ml of buffer containing HEPES (4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid), BSA (Bovine serum albumin) and sodium azide. Samples are then packed in padded envelopes and returned by mail to a laboratory at Oslo University Hospital for analysis and further storage at − 80 °C. Shipping time is estimated to 3–10 days. Immunochemical testing for blood in feces is performed continuously using the OC-Sensor Diana (Eiken Chemical, Tokyo, Japan) as samples are received at the laboratory.

All participants collected a one-time stool sample at home, using a sampling tube (Eiken Chemical Company, Tokyo, Japan) containing 2.0 mL buffer designed to minimize hemoglobin degradation, within 3 days before initiating bowel cleansing for colonoscopy.
The collected fecal material was sent to the laboratory sealed in a plastic bag. Fecal hemoglobin quantitation was performed by using OC-SENSOR DIANA (Eiken Chemical Company). FIT results were expressed in nanograms of hemoglobin per milliliter of buffer (ng Hb/mL), and the FIT positivity cutoff value was set at 100 ng Hb/mL (equivalent to 20 μg Hb/g feces) [16 (link)].

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.