Effect of multiple loading FIT sample collection devices on faecal haemoglobin concentration.

BACKGROUND: Faecal immunochemical tests (FIT) are routinely used in colorectal cancer (CRC) screening programmes around the world. More recently, quantitative FIT has been recommended to help triage patients presenting to primary care with symptoms suggestive of CRC. Participants collect faecal samples using sampling probes which are inserted into sample collection devices (SCDs) containing preservative buffer. The SCDs have an internal collar designed to remove excess sample. The aim of this study was to investigate the impact of multiple loading on faecal haemoglobin concentration (f-Hb) using SCDs of four FIT systems. METHODS: Pools of f-Hb negative samples were spiked with blood, homogenised and loaded into SCDs 1, 3 and 5 times, with insertion of the sampling probes into the SCDs with and without mixing between loads. The f-Hb was measured using the relevant FIT system. The percentage change in f-Hb for multiple loads was compared with a single load for each system for the mixed and unmixed groups. RESULTS: The p values show a significant difference (p < 0.05) in the mass and f-Hb for the mixed and unmixed group, for 1-3 and 1-5 loads for all systems. The median percentage change in f-Hb for the mixed is higher than the unmixed group. CONCLUSION: This study showed that multiple loading does significantly increase the f-Hb in the SCDs.

Risk-stratified faecal immunochemical testing (FIT) for urgent colonoscopy in Lynch syndrome during the COVID-19 pandemic.

BACKGROUND: Lynch syndrome is a hereditary cancer disease resulting in an increased risk of colorectal cancer. Herein, findings are reported from an emergency clinical service implemented during the COVID-19 pandemic utilizing faecal immunochemical testing ('FIT') in Lynch syndrome patients to prioritize colonoscopy while endoscopy services were limited. METHODS: An emergency service protocol was designed to improve colonoscopic surveillance access throughout the COVID-19 pandemic in England for people with Lynch syndrome when services were extremely restricted (1 March 2020 to 31 March 2021) and promoted by the English National Health Service. Requests for faecal immunochemical testing from participating centres were sent to the National Health Service Bowel Cancer Screening South of England Hub and a faecal immunochemical testing kit, faecal immunochemical testing instructions, paper-based survey, and pre-paid return envelope were sent to patients. Reports with faecal haemoglobin results were returned electronically for clinical action. Risk stratification for colonoscopy was as follows: faecal haemoglobin less than 10 µg of haemoglobin/g of faeces (µg/g)-scheduled within 6-12 weeks; and faecal haemoglobin greater than or equal to 10 µg/g-triaged via an urgent suspected cancer clinical pathway. Primary outcomes of interest included the identification of highest-risk Lynch syndrome patients and determining the impact of faecal immunochemical testing in risk-stratified colonoscopic surveillance. RESULTS: Fifteen centres participated from June 2020 to March 2021. Uptake was 68.8 per cent amongst 558 patients invited. For 339 eligible participants analysed, 279 (82.3 per cent) had faecal haemoglobin less than 10 µg/g and 60 (17.7 per cent) had faecal haemoglobin greater than or equal to 10 µg/g. In the latter group, the diagnostic accuracy of faecal immunochemical testing was 65.9 per cent and escalation to colonoscopy was facilitated (median 49 versus 122 days, χ2 = 0.0003, P < 0.001). CONCLUSION: Faecal immunochemical testing demonstrated clinical value for Lynch syndrome patients requiring colorectal cancer surveillance during the pandemic in this descriptive report of an emergency COVID-19 response service. Further longitudinal investigation on faecal immunochemical testing efficacy in Lynch syndrome is warranted and will be examined under the 'FIT for Lynch' study (ISRCTN15740250).

Exploring the utility and acceptability of Faecal immunochemical testing (FIT) as a novel intervention for the improvement of colorectal Cancer (CRC) surveillance in individuals with lynch syndrome (FIT for lynch study): a single-arm, prospective, multi-centre, non-randomised study.

BACKGROUND: Lynch Syndrome (LS) is an inherited cancer predisposition syndrome defined by pathogenic variants in the mismatch repair (MMR) or EPCAM genes. In the United Kingdom, people with LS are advised to undergo biennial colonoscopy from as early as 25 until 75 years of age to mitigate a high lifetime colorectal cancer (CRC) risk, though the consideration of additional surveillance intervention(s) through the application of non-invasive diagnostic devices has yet to be longitudinally observed in LS patients. In this study, we will examine the role of annual faecal immunochemical testing (FIT) alongside biennial colonoscopy for CRC surveillance in people with LS. METHODS/DESIGN: In this single-arm, prospective, non-randomised study, 400 LS patients will be recruited across 11 National Health Service (NHS) Trusts throughout the United Kingdom. Study inclusion requires a LS diagnosis, between 25 and 73 years old, and a routine surveillance colonoscopy scheduled during the recruitment period. Eligible patients will receive a baseline OC-Sensor™ FIT kit ahead of their colonoscopy, and annually for 3 years thereafter. A pre-paid envelope addressed to the central lab will be included within all patient mailings for the return of FIT kits and relevant study documents. A questionnaire assessing attitudes and perception of FIT will also be included at baseline. All study samples received by the central lab will be assayed on an OC-Sensor™ PLEDIA Analyser. Patients with FIT results of ≥6 µg of Haemoglobin per gram of faeces (f-Hb) at Years 1 and/or 3 will be referred for colonoscopy via an urgent colonoscopy triage pathway. 16S rRNA gene V4 amplicon sequencing will be carried out on residual faecal DNA of eligible archived FIT samples to characterise the faecal microbiome. DISCUSSION: FIT may have clinical utility alongside colonoscopic surveillance in people with LS. We have designed a longitudinal study to examine the efficacy of FIT as a non-invasive modality. Potential limitations of this method will be assessed, including false negative or false positive FIT results related to specific morphological features of LS neoplasia or the presence of post-resection anastomotic inflammation. The potential for additional colonoscopies in a subset of participants may also impact on colonoscopic resources and patient acceptability. TRIAL REGISTRATION: Trial Registration: ISRCTN, ISRCTN15740250 . Registered 13 July 2021.

A comparison of the faecal haemoglobin concentrations and diagnostic accuracy in patients suspected with colorectal cancer and serious bowel disease as reported on four different faecal immunochemical test systems.

OBJECTIVES: Faecal immunochemical tests for haemoglobin (FIT) are used in colorectal cancer (CRC) screening programmes and to triage patients presenting with symptoms suggestive of CRC for further bowel investigations. There are a number of quantitative FIT analytical systems available. Currently, there is no harmonisation or standardisation of FIT methods. The aim of the study was to assess the comparability of numerical faecal haemoglobin concentrations (f-Hb) obtained with four quantitative FIT systems and the diagnostic accuracy at different f-Hb thresholds. METHODS: A subgroup of the National Institute for Health and Care Excellence (NICE) FIT study, a multicentre, prospective diagnostic accuracy study were sent four FIT specimen collection devices from four different FIT systems or two FIT devices for one FIT system. Faecal samples were examined and analysis of results carried out to assess difference between methods at thresholds of limit of detection (LoD), 10 µg haemoglobin/g faeces (µg/g) and 100 µg/g. RESULTS: 233 patients returned specimen collection devices for examination on four different systems; 189 patients returned two FIT kits for one system. At a threshold of 100 µg/g the sensitivity is the same for all methods. At lower thresholds of LoD and 10 µg/g differences were observed between systems in terms of patients who would be referred and diagnostic accuracies. CONCLUSIONS: The lack of standardisation or harmonisation of FIT means that differences are observed in f-Hb generated on different systems. Further work is required to understand the clinical impact of these differences and to minimise them.

Evaluation of a faecal calprotectin method using the OC-SENSOR PLEDIA.

OBJECTIVES: The National Institute for Health and Care Excellence recommends faecal calprotectin (f-cal) to help differentiate inflammatory bowel diseases from irritable bowel syndrome. Faecal samples for calprotectin have historically been collected at home by patients into screw-top pots and sent to laboratories where calprotectin is extracted and analysed. Faecal haemoglobin (f-Hb) samples are collected at home into specific collection devices containing stabilising buffer. We evaluated the OC-FCa method for f-cal, developed by Eiken Chemical Co., Ltd. (Japan) that uses the same collection device and analyser as f-Hb. METHODS: OC-FCa was assessed for limit of blank (LOB), limit of detection (LOD), limit of quantification (LOQ), within and between-run imprecision, linearity, prozone, recovery and carryover. A method comparison against the BÜHLMANN fCAL® turbo (BÜHLMANN Laboratories AG, Switzerland) was performed using patient samples and EQA. RESULTS: The LOB was 3 µg calprotectin/g faeces (µg/g), LOD 8 µg/g and LOQ 20 µg/g. Within and between-run imprecision was <5%; linearity was good (R2 > 0.99); prozone was appropriately detected; recovery was 99.6%; no observed carryover. OC-FCa showed a strong positive bias compared with BÜHLMANN fCAL® turbo (Z=-5.3587, p < 0.001). When categorised using our local pathway, which interprets calprotectin concentrations and need for further investigation, Cohen's Kappa demonstrates substantial agreement at <50 µg/g (κ=0.80) and >150 µg/g (κ=0.63) and fair agreement (κ=0.22) in the borderline category 50-150 µg/g. CONCLUSIONS: The OC-FCa method performed well in the evaluation. With the lack of standardisation for f-cal a clinical study is required to evaluate the positive bias and establish suitable cut-off levels.

Comparison of the QuikRead go® point-of-care faecal immunochemical test for haemoglobin with the FOB Gold Wide® laboratory analyser to diagnose colorectal cancer in symptomatic patients.

OBJECTIVES: Faecal immunochemical testing for haemoglobin (FIT) is used to triage patients for colonic investigations. Point-of-care (POC) FIT devices on the market have limited data for their diagnostic accuracy for colorectal cancer (CRC). Here, a POC FIT device is compared with a laboratory-based FIT system using patient collected samples from the urgent referral pathway for suspected CRC. METHODS: A prospective, observational cohort study. Patients collected two samples from the same stool. These were measured by POC QuikRead go® (Aidian Oy, Espoo, Finland) and laboratory-based FOB Gold Wide® (Sentinel Diagnostics, Italy). Faecal haemoglobin <10 µg haemoglobin/g of faeces was considered as negative. At this threshold, comparisons between the two systems were made by calculating percentage agreement and Cohen's kappa coefficient. Proportion of negative results were compared with Chi squared testing. Sensitivities for CRC were calculated. RESULTS: A total of 629 included patients provided paired samples for FIT to compare the QuikRead go® and FOB Gold Wide®. The agreement around the negative threshold was 83.0% and Cohen's kappa coefficient was 0.54. The QuikRead go® reported 440/629 (70.0% of samples) as negative compared to 523/629 (83.1%) for the FOB Gold Wide®, this difference was significant (p-value<0.001). Sensitivities for CRC detection by the QuikRead go® and FOB Gold Wide® were 92.9% (95% confidence interval (CI): 68.5-98.7%) and 100% (CI: 78.5-100%) respectively. CONCLUSIONS: Both systems were accurate in their ability to detect CRC. Whilst good agreement around the negative threshold was identified, more patients would be triaged to further colonic investigation if using the QuikRead go®.

Impact of changing from a guaiac faecal occult blood test to a faecal immunochemical test in a national screening programme: Results from a pilot study within the national bowel cancer screening programme in England.

OBJECTIVE: Testing for occult blood in faeces is widely used in bowel cancer screening around the world. In many programmes, the faecal immunochemical test (FIT) is replacing the traditional guiaic faecal occult blood test (gFOBT). There have been a number of reports on the clinical impact of making this change; yet, no-one has considered the pre-analytical and analytical impact of moving from a gFOBT to a FIT bowel cancer screening programme. METHODS: We interrogated data obtained in a FIT pilot carried out in England in 2014 to assess the timeliness of specimen collection device return time and analysis for gFOBT and FIT, the impact of time to analysis on faecal haemoglobin (f-Hb) concentration, and any differences observed between analyses carried out at two different testing laboratories. RESULTS: FIT kits were returned on average 5.6 days sooner than gFOBT. The time to analysis for FIT leads to an overall rise in f-Hb concentration within the manufacturer's stated 14-day stability period. CONCLUSION: Both these factors are important considerations for laboratories when considering setting up a bowel cancer screening programme, especially if transitioning from gFOBT to FIT. Our data also support previous evidence of males having a higher f-Hb than females and demonstrate that after adjusting for sex, age and screening hub, neither index of multiple deprivation nor screening episode significantly affected f-Hb.

Assessment of the analytical performance of point-of-care faecal immunochemical tests for haemoglobin.

BACKGROUND: The faecal immunochemical test (FIT) detects the presence of haemoglobin (Hb) in faeces. It is used as a screening tool for colorectal cancer (CRC) and increasingly to triage patients presenting with symptoms of CRC. A number of quantitative point-of-care (POC) FIT systems marketed for professional use and intended for use in a clinical setting are available. Here we reviewed the POC FIT systems available; three (Eurolyser Cube, OC-Sensor iO and QuikRead go) were evaluated to assess their performance against manufacturers' claims and suitability for use in a clinical setting. METHODS: The analytical evaluation of the POC FIT systems was undertaken using Hb lysates, patient samples and an external quality assessment sample. The evaluation focused on linearity, recovery, imprecision, prozone effect, Hb variant detection and suitability for use in a clinical setting. RESULTS: All three POC FIT systems performed to their manufacturer's claims and demonstrated good analytical performance with acceptable linearity, recovery, within- and between-run imprecision. The QuikRead go and OC-Sensor iO were able to accurately detect samples with results above their measuring range. However, because of a prozone effect the Eurolyser Cube gave falsely low results when using high concentrations of Hb. The QuikRead go performed best in the usability assessment due to portability and timeliness of result. CONCLUSION: Each system performed according to their manufacturers' claims. The QuikRead go and OC-Sensor iO are suitable for use. The Eurolyser Cube is not recommended because of the risk of falsely low results.

An evaluation of ten external quality assurance scheme (EQAS) materials for the faecal immunochemical test (FIT) for haemoglobin.

Objectives: External quality assessment schemes (EQAS) are being established worldwide to support the faecal immunochemical test (FIT) for haemoglobin (Hb). FIT is widely used as a screening test for colorectal cancer and increasingly in assessment of patients presenting with symptoms. EQA for FIT is provided in several matrices, each unique to the individual scheme. These include Hb suspended in a faecal-like matrix, lyophilised samples and liquid samples. The aim of this study was to evaluate commercially available EQAS and assess their suitability for use. Methods: Ten EQAS provided material for the study. EQA samples were analysed on four quantitative FIT systems. 15 faecal-like matrix samples were loaded per concentration per FIT system. Reconstituted lyophilised samples were examined five times on three separate occasions and liquid samples were examined 10 times per concentration per FIT system. The coefficient of variation (CV) was calculated per concentration of EQA for each FIT system. Results: Results from faecal-like matrix schemes had a higher median CV (12.4-19.0%) when compared to those from schemes providing liquid matrices (0.8-2.3%). The spread of CV values was also higher for results from faecal-like matrix schemes with an interquartile range (IQR) 4.4-24.0% vs. liquid IQR range of 0.3-2.5%. Conclusions: Hb results from faecal-like matrices, whilst more aligned to a patient or participant sample, are prone to pre-examination variation so do not assess the analytical accuracy of a FIT system. Liquid matrices are not prone to pre-examination variation and are better able to assess the accuracy of a FIT system.

Analytical evaluation of four faecal immunochemistry tests for haemoglobin.

Objectives: Faecal immunochemical tests (FIT) for haemoglobin (Hb) are being used in the investigation of colorectal cancer. These tests use antibodies raised to the globin moiety of human Hb. Here, four automated quantitative FIT systems (HM-JACKarc, NS-Prime, OC-Sensor PLEDIA and SENTiFIT 270) are evaluated analytically to confirm whether the performance of the systems meet the manufacturers' claims. Methods: Assessment of the analytical performance of the FIT systems was undertaken using Hb lysates, real patient samples and external quality assessment (EQA) samples. This analytical assessment focused on detection characteristics, imprecision, linearity, prozone effect, recovery and carryover. Results: All four methods demonstrated good analytical performance, with acceptable within- and between-run imprecision, good recovery of f-Hb and limited carryover of samples. They also all show good linearity across the range of concentrations tested. The results of EQA samples showed different variations from the target values (-52 to 45%), due to the absence of standardisation across the different methods. Conclusions: All four systems are fit for purpose and have an analytical performance as documented by their manufacturers.

Faecal immunochemical tests versus colonoscopy for post-polypectomy surveillance: an accuracy, acceptability and economic study.

BACKGROUND: In the UK, patients with one or two adenomas, of which at least one is ≥ 10 mm in size, or three or four small adenomas, are deemed to be at intermediate risk of colorectal cancer (CRC) and referred for surveillance colonoscopy 3 years post polypectomy. However, colonoscopy is costly, can cause discomfort and carries a small risk of complications. OBJECTIVES: To determine whether or not annual faecal immunochemical tests (FITs) are effective, acceptable and cost saving compared with colonoscopy surveillance for detecting CRC and advanced adenomas (AAs). DESIGN: Diagnostic accuracy study with health psychology assessment and economic evaluation. SETTING: Participants were recruited from 30 January 2012 to 30 December 2013 within the Bowel Cancer Screening Programme in England. PARTICIPANTS: Men and women, aged 60-72 years, deemed to be at intermediate risk of CRC following adenoma removal after a positive guaiac faecal occult blood test were invited to participate. Invitees who consented and returned an analysable FIT were included. INTERVENTION: We offered participants quantitative FITs at 1, 2 and 3 years post polypectomy. Participants testing positive with any FIT were referred for colonoscopy and not offered further FITs. Participants testing negative were offered colonoscopy at 3 years post polypectomy. Acceptibility of FIT was assessed using discussion groups, questionnaires and interviews. MAIN OUTCOME MEASURES: The primary outcome was 3-year sensitivity of an annual FIT versus colonoscopy at 3 years for detecting advanced colorectal neoplasia (ACN) (CRC and/or AA). Secondary outcomes included participants' surveillance preferences, and the incremental costs and cost-effectiveness of FIT versus colonoscopy surveillance. RESULTS: Of 8008 invitees, 5946 (74.3%) consented and returned a round 1 FIT. FIT uptake in rounds 2 and 3 was 97.2% and 96.9%, respectively. With a threshold of 40 µg of haemoglobin (Hb)/g faeces (hereafter referred to as µg/g), positivity was 5.8% in round 1, declining to 4.1% in round 3. Over three rounds, 69.2% (18/26) of participants with CRC, 34.3% (152/443) with AAs and 35.6% (165/463) with ACN tested positive at 40 µg/g. Sensitivity for CRC and AAs increased, whereas specificity decreased, with lower thresholds and multiple rounds. At 40 µg/g, sensitivity and specificity of the first FIT for CRC were 30.8% and 93.9%, respectively. The programme sensitivity and specificity of three rounds at 10 µg/g were 84.6% and 70.8%, respectively. Participants' preferred surveillance strategy was 3-yearly colonoscopy plus annual FITs (57.9%), followed by annual FITs with colonoscopy in positive cases (31.5%). FIT with colonoscopy in positive cases was cheaper than 3-yearly colonoscopy (£2,633,382), varying from £485,236 (40 µg/g) to £956,602 (10 µg/g). Over 3 years, FIT surveillance could miss 291 AAs and eight CRCs using a threshold of 40 µg/g, or 189 AAs and four CRCs using a threshold of 10 µg/g. CONCLUSIONS: Annual low-threshold FIT with colonoscopy in positive cases achieved high sensitivity for CRC and would be cost saving compared with 3-yearly colonoscopy. However, at higher thresholds, this strategy could miss 15-30% of CRCs and 40-70% of AAs. Most participants preferred annual FITs plus 3-yearly colonoscopy. Further research is needed to define a clear role for FITs in surveillance. FUTURE WORK: Evaluate the impact of ACN missed by FITs on quality-adjusted life-years. TRIAL REGISTRATION: Current Controlled Trials ISRCTN18040196. FUNDING: National Institute for Health Research (NIHR) Health Technology Assessment programme, NIHR Imperial Biomedical Research Centre and the Bobby Moore Fund for Cancer Research UK. MAST Group Ltd provided FIT kits.

Faecal immunochemical tests (FIT) versus colonoscopy for surveillance after screening and polypectomy: a diagnostic accuracy and cost-effectiveness study.

OBJECTIVE: The English Bowel Cancer Screening Programme (BCSP) recommends 3 yearly colonoscopy surveillance for patients at intermediate risk of colorectal cancer (CRC) postpolypectomy (those with three to four small adenomas or one ≥10 mm). We investigated whether faecal immunochemical tests (FITs) could reduce surveillance burden on patients and endoscopy services. DESIGN: Intermediate-risk patients (60-72 years) recommended 3 yearly surveillance were recruited within the BCSP (January 2012-December 2013). FITs were offered at 1, 2 and 3 years postpolypectomy. Invitees consenting and returning a year 1 FIT were included. Participants testing positive (haemoglobin ≥40 µg/g) at years one or two were offered colonoscopy early; all others were offered colonoscopy at 3 years. Diagnostic accuracy for CRC and advanced adenomas (AAs) was estimated considering multiple tests and thresholds. We calculated incremental costs per additional AA and CRC detected by colonoscopy versus FIT surveillance. RESULTS: 74% (5938/8009) of invitees were included in our study having participated at year 1. Of these, 97% returned FITs at years 2 and 3. Three-year cumulative positivity was 13% at the 40 µg/g haemoglobin threshold and 29% at 10 µg/g. 29 participants were diagnosed with CRC and 446 with AAs. Three-year programme sensitivities for CRC and AAs were, respectively, 59% and 33% at 40 µg/g, and 72% and 57% at 10 µg/g. Incremental costs per additional AA and CRC detected by colonoscopy versus FIT (40 µg/g) surveillance were £7354 and £180 778, respectively. CONCLUSIONS: Replacing 3 yearly colonoscopy surveillance in intermediate-risk patients with annual FIT could reduce colonoscopies by 71%, significantly cut costs but could miss 30%-40% of CRCs and 40%-70% of AAs. TRIAL REGISTRATION NUMBER: ISRCTN18040196; Results.

Does the mass of sample loaded affect faecal haemoglobin concentration using the faecal immunochemical test?

Background Quantitative faecal immunochemical tests (FIT) for haemoglobin are being used for colorectal cancer (CRC) screening for asymptomatic populations and are being indicated as a suitable test to rule out CRC in symptomatic populations. Faecal samples are typically collected by patients using a probe attached to the cap of a device which is inserted into a collection device into the preservative buffer, passing through a collar to remove excess sample: this process has potential for pre-analytical error. This study investigates whether faecal haemoglobin concentration (f-Hb) results are affected by the mass and method of sample collection. Methods Faecal samples with detectable f-Hb were loaded into collection devices from four manufacturers using increasing masses of sample. The f-Hb in the device buffer was measured using the relevant analyser. The results from the minimum recommended load were compared with results of 'sample overloading'. Results The variation in the faecal mass added to the probe (overall CVs: EXTEL HEMO AUTO-MC Collection Picker 300%, OC-Auto Sampling Bottle 3 237%, SENTiFIT pierceTube 264%, Specimen Collection Container A 250%), was more than the variation in f-Hb (respective overall CVs: 62%, 35%, 47%, 39%). The mass of faeces added to the probes increased significantly ( P < 0.0001 for all four devices), but the f-Hb did not increase significantly (EXTEL HEMO AUTO-MC Collection Picker P = 0.6820, OC-Auto Sampling Bottle 3 P = 0.9368, SENTiFIT pierceTube P = 0.7551, Specimen Collection Container A P = 0.6864). Conclusion The mass of sample loaded onto the probe did not impact the f-Hb significantly using all four tested devices.