Analytical evaluation of eight qualitative FIT for haemoglobin products, for professional use in the UK.

OBJECTIVES: Qualitative faecal immunochemical tests for haemoglobin (FIT), for triaging for colorectal cancer investigations, are available for professional use. The aim was to evaluate these lateral flow tests. No previous analytical evaluations have been published. METHODS: Analytical sensitivity (AS) was assessed using samples spanning manufacturers' quoted AS, concurrently with the quantitative OC-SENSOR PLEDIA, using Hb-spiked samples in manufacturers' buffer (n≥5; ≤9-99 ng Hb/mL buffer), Hb-spiked faeces (n=6; <2-34 µg Hb/g faeces) and natural faeces (n=17; <2-82 µg/g); concentrations for 50 %/100 % Hb-detected were compared with quoted AS. Compatibility with two external quality assessment schemes (EQAS) (n=9; 3-96 µg/g) and prozone compared with manufacturers limits (n=9; 2,500-10,000,000 ng/mL) were tested. Ease-of-use by five healthcare personnel was assessed. RESULTS: Seven products showed lower AS (ng/mL) than manufacturers quoted using Hb-spiked aqueous samples compared with OC-SENSOR, one was equivocal; six manufacturers quoted AS in µg/g, five showed lower AS using Hb-spiked faeces. Results were similar but less consistent for natural faeces. Result lines for low concentrations can be faint and open to interpretation. Results were consistent with manufacturers quoted prozone limits. Results were consistent for seven products for two EQAS. The ease-of-use was 68.5-85.6 %; products with lower scores could be improved with better instructions and sample bottles. CONCLUSIONS: AS was lower for seven products (aqueous samples) and five products (aqueous/faecal samples) and prozone consistent with manufacturers expected concentrations, compared with OC-SENSOR. EQAS results were mostly consistent with expected results; products can be used by healthcare professionals, though some manufacturer improvements could be made.

Comparison and commutability study among four faecal immunochemical tests (FIT) systems.

OBJECTIVES: Faecal immunochemical tests for haemoglobin (FIT) are used in colorectal cancer screening programs around the world and increasingly for triage of symptomatic patients. FIT results are currently not traceable to a common reference standard and results obtained on various FIT systems may not be equivalent. The size of the bias between the systems is difficult to quantify due to the complex pre-analytical aspects of FIT. METHODS: This study aimed to quantify the bias and the correlation between four FIT systems by measuring a panel of 38 faecal samples while limiting the effect of the pre-analytical aspects. In addition, the commutability of seven candidate reference materials (RM) was assessed. RESULTS: Pairwise method comparisons based on faecal samples demonstrated Pearson correlation coefficients ranging between 0.944 and 0.970 and an average proportional bias of -30 to -35 % for one FIT system compared to the other three. The relative standard deviation among biases of the individual samples was around 20 %. Due to these sample specific differences, no decisive conclusions could be drawn in the commutability study. However, two candidate RMs, prepared in the FIT system-specific storage/extraction buffers, had a better commutable profile than the other five. CONCLUSIONS: The use of a common threshold for all FIT systems is currently not possible due to the presence of a proportional bias. We have identified potential commutable RMs to take to further studies on the production of a common calibrator, with the aim being to reduce the analytical bias observed on different FIT systems.

Faecal haemoglobin concentration and colorectal cancer site, stage and grade in a symptomatic cohort.

AIM: Minimal evidence exists regarding faecal immunochemical tests (FITs) for colorectal cancer (CRC) site, stage and grade in symptomatic patients. The primary aim is to determine any association between faecal haemoglobin concentration (f-Hb) (analysed with OC-Sensor™ Pledia) and these prognostic factors. The secondary aim is to determine the association between f-Hb and anaemia, microcytosis and iron deficiency (Hb, mean corpuscular volume [MCV] and ferritin). METHODOLOGY: Symptomatic 2-week wait CRC patients with FIT were included (July 2019-October 2022). Median f-Hb and interquartile range according to sex, stage, grade and site (right-sided, caecum to transverse colon, R-CRC; left-sided, splenic flexure to rectum, L-CRC) were compared using the Mann-Whitney U test. Hb, MCV and ferritin were categorized into two groups and the median f-Hb was compared using the Mann-Whitney U test. RESULTS: In all, 114 patients (57 women, 57 men) were studied; 46 had R-CRC (f-Hb = 113 µg Hb/g) and 68 had L-CRC (f-Hb = 342 µg Hb/g) (P = 0.07). Sixty-nine were moderately differentiated CRC (f-Hb = 183 µg Hb/g) and 29 were poorly differentiated (f-Hb = 866 µg Hb/g) (P = 0.04). By T-stage, 35 were early (T1/2) (f-Hb = 170 µg Hb/g) and 79 were advanced (T3/4) (f-Hb = 200 µg Hb/g) (P = 0.06). The relationship between f-Hb and Hb, MCV and ferritin was not significant. Poorly differentiated (P = 0.04) and later stage (P = 0.02) R-CRC had significantly lower f-Hb compared to L-CRC. CONCLUSIONS: Right-sided CRC is associated with lower f-Hb than left. Poorly differentiated and later staged L-CRC had higher median f-Hb. These data add to existing evidence suggesting that FIT may be less sensitive for right-sided CRC. Strategies to mitigate the potential for missed or FIT-negative right-sided CRC are required.

The repeat FIT (RFIT) study: Does repeating faecal immunochemical tests provide reassurance and improve colorectal cancer detection?

AIM: Faecal immunochemical tests (FIT) are highly sensitive for colorectal cancer (CRC) detection. Little evidence exists regarding repeat FIT. The repeat FIT (RFIT) study aimed to determine whether second and third FIT provide reassurance and improve CRC or significant bowel disease (SBD) identification. METHODS: This was a prospective observational study. Patients recruited from urgent referrals returned three FIT and underwent colonoscopy. Chi-square tests compared categorical data. Diagnostic accuracy variables (sensitivity/specificity/positive predictive value [PPV]/negative predictive value [NPV]) were calculated for one, two and three FIT (95% CI). Three negative FIT (<10 µg Hb/g of faeces [µg/g]) groups (one, two, three) were compared with positive groups (one or more FIT ≥10 µg/g). CRC and SBD detection rates were compared by strategy. RESULTS: A total of 460 patients (mean age: 66.8 years, 233 males and 227 females, 23 CRC, 80 SBD) were included in the study. For one, two and three negative FIT, CRC sensitivity remained static (95.7%); specificity (44.6%, 40.7% and 38.4%) and NPV decreased (99.5%, 99.4% and 99.4%). For SBD, sensitivity increased (78.8%, 83.8% and 86.3%), specificity decreased (47.4%, 43.7% and 41.6%) and NPV increased (91.4%, 92.7% and 93.5%). In one, two and three positive FIT groups, CRC detection was 8.3%,16.1% and 20.9%. CRC mean FIT was 150 µg/g, <6 µg/g for benign pathology. CONCLUSIONS: One or more negative FIT increases the sensitivity for CRC/SBD. Repeating FIT provides greater differentiation of patients with and without CRC/SBD compared to single FIT but is associated with decreased specificity and PPV. Multiple negative FIT may offer reassurance; however, application of repeating FIT may be restricted given the associated increase in investigations.

Impact of changes to the interscreening interval and faecal immunochemical test threshold in the national bowel cancer screening programme in England: results from the FIT pilot study.

INTRODUCTION: The NHS Bowel Cancer Screening Programme (BCSP) faces endoscopy capacity challenges from the COVID-19 pandemic and plans to lower the screening starting age. This may necessitate modifying the interscreening interval or threshold. METHODS: We analysed data from the English Faecal Immunochemical Testing (FIT) pilot, comprising 27,238 individuals aged 59-75, screened for colorectal cancer (CRC) using FIT. We estimated screening sensitivity to CRC, adenomas, advanced adenomas (AA) and mean sojourn time of each pathology by faecal haemoglobin (f-Hb) thresholds, then predicted the detection of these abnormalities by interscreening interval and f-Hb threshold. RESULTS: Current 2-yearly screening with a f-Hb threshold of 120 µg/g was estimated to generate 16,092 colonoscopies, prevent 186 CRCs, detect 1142 CRCs, 7086 adenomas and 4259 AAs per 100,000 screened over 15 years. A higher threshold at 180 µg/g would reduce required colonoscopies to 11,500, prevent 131 CRCs, detect 1077 CRCs, 4961 adenomas and 3184 AAs. A longer interscreening interval of 3 years would reduce required colonoscopies to 10,283, prevent 126 and detect 909 CRCs, 4796 adenomas and 2986 AAs. CONCLUSION: Increasing the f-Hb threshold was estimated to be more efficient than increasing the interscreening interval regarding overall colonoscopies per screen-benefited cancer. Increasing the interval was more efficient regarding colonoscopies per cancer prevented.

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.

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.

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®.

Finding the needle in the haystack: the diagnostic accuracy of the faecal immunochemical test for colorectal cancer in younger symptomatic patients.

AIM: Detection of early onset colorectal cancer is challenging, and remains a rare diagnosis amongst younger people with gastrointestinal symptoms. We investigated whether faecal immunochemical testing (FIT) could identify younger patients at higher risk of colorectal cancer or serious bowel disease including colorectal cancer, inflammatory bowel disease or advanced adenomas. METHODS: A subgroup analysis was performed of symptomatic patients under 50 years of age (<50) from the NICE FIT study, a multicentre, prospective diagnostic accuracy study of FIT conducted between October 2017 and December 2019. The diagnostic accuracy of FIT for colorectal cancer and serious bowel disease was investigated in younger patients at different faecal haemoglobin (f-Hb) cut-offs of 2, 10 and 150 µg blood/g faeces (µg/g). RESULTS: Early onset colorectal cancer was diagnosed in 1.5% (16/1103) of younger symptomatic patients. The sensitivity of FIT for younger patients aged <50 was 87.5% (95% CI 61.7%-98.4%), 81.3% (54.4%-96.0%) and 68.8% (41.3%-89.0%) at f-Hb cut-offs of 2, 10 and 150 µg/g, respectively. The positive predictive value for colorectal cancer increased from 4.2% (2.3%-6.9%) to 11.5% (5.9%-19.6%) at cut-offs of 2 and 150 µg/g, while the positive predictive value for serious bowel disease increased from 31.3% (26.3%-36.5%) to 65.6% (55.2%-75.0%) at the same cut-offs. The negative predictive value of FIT for colorectal cancer remained above 99.5% at all cut-offs. CONCLUSION: Detectable f-Hb on FIT in symptomatic younger patients may indicate referral for investigation of colorectal cancer and serious bowel disease.

Using the faecal immunochemical test in patients with rectal bleeding: evidence from the NICE FIT study.

AIM: The aim of this work was to investigate whether the faecal immunochemical test (FIT) could safely rule out colorectal cancer (CRC) in patients with rectal bleeding (RB). METHOD: This was a multicentre, double-blinded diagnostic accuracy study in 50 National Health Service hospitals. Patients referred from primary care with suspected CRC on an urgent 2-week-wait pathway were asked to perform a FIT prior to colonoscopy. The primary outcome measure was the sensitivity of the FIT for CRC in patients with RB versus nonrectal bleeding symptoms (NRB). The secondary outcome measures included the diagnostic accuracy of the FIT for CRC and other serious bowel disease. RESULTS: Of 9822 patients included in the study, 3143 (32.0%) were referred with RB. CRC was present in 4.7% of patients with RB versus 2.7% of patients with NRB (p < 0.05). Faecal haemoglobin (f-Hb) was detectable (>2 µg/g) in 44.1% of patients with RB and 33.9% with NRB (p < 0.05). In RB patients, CRC was present in 10.4% when f-Hb was >2 µg/g compared with 0.1% when f-Hb was not detected. Flexible sigmoidoscopy in this group would further reduce the risk of CRC to 0.03%. The sensitivity of the FIT for CRC in RB versus NRB groups was 98.6% (95% CI 95.2%-99.8%) vs 95.6% (91.5%-98.1%) for f-Hb >2 µg/g and 96.6% (92.2%-98.9%) vs 86.3 (80.4%-90.9%) for f-Hb >10 µg/g. CONCLUSION: Faecal haemoglobin is not always detectable in patients with RB; 56% of patients had undetectable f-Hb (<2 µg/g) and CRC was present in 0.1%. The high sensitivity of the FIT can be used to rule out CRC in patients with RB and triage them more appropriately for investigation.

Adoption of faecal immunochemical testing for 2-week-wait colorectal patients during the COVID-19 pandemic: an observational cohort study reporting a new service at a regional centre.

AIM: The COVID-19 pandemic has resulted in the near-complete loss of routine endoscopy services. We describe a major reorganization of service at a regional referral centre (Royal Surrey NHS Foundation Trust) to manage the crisis. Faecal immunochemical testing (FIT) was implemented for triage to make optimum use of limited diagnostic resources. Consultations were switched from face-to-face to telephone. Our aim was to evaluate the impact FIT had on resource allocation and patient diagnoses in the first 3 months of use. METHOD: All colorectal 2-week-wait patient referrals were posted a pack requesting FIT and notification of telephone consultation. A prepaid envelope was included for return of the samples. At consultation, FIT was incorporated with the presenting symptoms to guide the choice of investigation and triage urgency. FIT ≥10 µg/g was interpreted as positive. Outcome data were collected prospectively and compared with retrospective audit data from prepandemic levels across 3 months. RESULTS: From 26 March 2020 to 2 July 381 patients were referred who were invited to provide FIT samples and underwent telephone consultations. Three hundred and fifty eight FIT samples were returned (94%). Onward referral for colonoscopy reduced from 62% to 34% (P < 0.001). There were 14 colorectal cancers (CRC) (3.7%) diagnosed, which was not statistically different from the prepandemic level of 3.9% (P = 0.995). Twelve of the 14 patients with a CRC diagnosis had provided samples; all 12 had FIT ≥10 µg/g and were offered fast-track investigations. CONCLUSIONS: The incorporation of FIT optimized the allocation of limited resources to triage those who required urgent colonic investigation for detecting CRC.

Diagnostic accuracy of point of care faecal immunochemical testing using a portable high-speed quantitative analyser for diagnosis in 2-week wait patients.

AIM: Laboratory-based faecal immunochemical testing (FIT) is the gold standard for detecting the presence of blood in the stool. The aim was to perform a diagnostic accuracy study to confirm if a point of care (POC) analyser for FIT could be safely used as an adjunct in the triage and management of 2-week wait (TWW) colorectal patients. METHODS: The Point of Care Faecal Immunochemical Testing (POC FIT) prospective observational cohort study was designed for TWW patients at a regional referral centre. Between July 2019 and March 2020, patients were invited to perform and bring a FIT sample to clinic. FIT was completed within the clinic appointment using a POC quantitative analyser that has a 2-min processing time (QuikRead go®). Patients and clinicians were blinded to results within the clinic appointment. The results were compared with subsequent diagnostic outcomes. Faecal haemoglobin of <10 µg haemoglobin/g of faeces was considered a negative result. Sensitivities for colorectal cancer (CRC) and combined serious bowel disease (SBD) were calculated using this pre-determined cut-off. RESULTS: A total of 553 patients were included for analytical comparison with diagnostic outcomes. There were 14 (2.5%) patients with CRC and 52 (9.4%) with SBD. The sensitivities for CRC and SBD were 92.9% (95% CI 68.5%-98.7%) and 76.9% (95% CI 63.9%-86.3%) respectively. 379 (68.5%) patients had a negative FIT result (negative predictive value for CRC was 99.7%). CONCLUSIONS: This POC FIT device is a useful adjunct to better manage TWW patients. The high observed sensitivity for CRC offers opportunities, within a single consultation, for improved triage and rationalization of investigation for those with bowel symptoms.

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.

Evaluation of the 25-hydroxy vitamin D assay on a fully automated liquid chromatography mass spectrometry system, the Thermo Scientific Cascadion SM Clinical Analyzer with the Cascadion 25-hydroxy vitamin D assay in a routine clinical laboratory.

Background Liquid chromatography-tandem mass spectrometry (LC-MS/MS) offers advantages over immunoassay due to its increased specificity and ability to multiplex metabolites within a single run. Wide scale adoption of LC-MS/MS in routine clinical laboratories is restricted in part due to the high level of technical expertise required. The Thermo Scientific™ Cascadion™ SM Clinical Analyzer is the first fully automated, random access clinical analyser that utilises LC-MS/MS technology. We report an analytical validation of the 25-hydroxy vitamin D2 and D3 assays on the Cascadion Analyzer and an assessment of its performance within a routine clinical laboratory. Methods Analyser usability was assessed by staff with no previous experience of LC-MS/MS. An analytical validation included analysis of 154 patient samples on two different Cascadion Analyzers and a four-way method comparison of 146 patient samples on Roche and Siemens immunoassays and an in-house LC-MS/MS method. Accuracy was assessed using external quality assurance and reference materials. Seven third party IQC materials were tested on Cascadion. Results Cascadion proved easy to use by scientific and non-scientific staff. The assay passed all validation criteria. Excellent agreement was demonstrated between two different Cascadions (y = 0.97x + 3.9 nmol/L, r2 > 0.99). A method comparison demonstrated no significant difference (p > 0.05) between the Cascadion and the Roche immunoassay. A significant difference (p < 0.0001) was observed between the Cascadion and an LC-MS/MS and Siemens methods. Results obtained from EQA and reference material showed a mean bias of +3.09% and all samples were within ±10% of assigned concentrations. All third party IQC samples tested were compatible for use with Cascadion. Conclusions The Cascadion Analyzer is a fully automated LC-MS/MS system that requires no prior LC-MS/MS expertise. The vitamin D assays demonstrated excellent performance with high levels of accuracy.

Detection capability of quantitative faecal immunochemical tests for haemoglobin (FIT) and reporting of low faecal haemoglobin concentrations.

Faecal immunochemical tests for haemoglobin (FIT) are widely used in asymptomatic population screening for colorectal (bowel) cancer. FIT are also used to assist with the assessment of patients presenting with lower abdominal symptoms. Quantitative FIT allow the generation of numerical estimates of faecal haemoglobin (f-Hb) concentrations. There is now great interest in "low" f-Hb concentrations in these clinical settings: in consequence, knowledge of the detection capability is very important for f-Hb concentration examinations. There are a number of current problems associated with the reporting of low f-Hb concentrations and wide misunderstanding of the metrological aspects of examinations of f-Hb at low concentrations. These would be solved if the detectability characteristics of f-Hb concentration examinations, namely, the limit of blank (LoB), limit of detection (LoD) and limit of quantitation (LoQ), were generated, validated and used in reporting systems exactly as recommended in the EP17-A2 guideline of the Clinical Laboratory Standards Institute. LoB and LoD are statistical concepts, but the LoQ depends on definition of analytical performance specifications (APS). In this Opinion Paper proposals for interim APS are made, based on the current state of the art achieved with examinations of faecal samples. It is proposed that LoQ is determined at an examination imprecision of CV≤10% using faecal samples naturally positive for Hb rather than faeces spiked with haemolysate. Detailed proposals for reporting f-Hb data at low concentrations are also made.

GP participation in increasing uptake in a national bowel cancer screening programme: the PEARL project.

BACKGROUND: The NHS Bowel Cancer Screening Programme (BCSP) in England does not involve general practitioners (GPs). Uptake is ∼58%. The Practice Endorsed Additional Reminder Letter (PEARL) study piloted a GP-endorsed reminder letter. METHODS: General practices in Wessex with uptake <55% (prevalent invitations) were invited to participate. Subjects who had been invited for screening, sent a standard 28-day BCSP reminder letter but had not returned a test kit within 30 days of the standard reminder were sent a second reminder letter bearing the GP's letterhead and signature. Uptake was compared between PEARL and non-PEARL practices by standardised uptake ratio (standardised for prior prevalent uptake and other confounders). In addition, 25 non-PEARL practices were matched with PEARL practices for prior prevalent uptake and number of invitees. RESULTS: Twenty-five practices agreed to participate. A total of 3149 GP-endorsed reminders were sent. Uptake in the PEARL practices was 54% compared with 51% in the matched-control practices. The adjusted RR for uptake was 1.08 (95% CI: 1.05, 1.11, P<0.001) for all invitees and 2.18 (1.79, 2.66, P<0.001) for invitees who had not returned a kit following the standard reminder. CONCLUSIONS: The GP-endorsed reminder was associated with significantly increased uptake among subjects not responding to the standard reminder letter.

Faecal occult blood testing for colorectal cancer screening: the past or the future.

Screening for colorectal cancer (CRC) reduces CRC mortality; many countries have implemented population-based CRC screening programmes and many more are poised to do so. Whilst several different CRC screening modalities are available, choice will be influenced by cost, available resources (e.g. high-quality colonoscopy) and acceptability of the test by the invited population. For CRC screening, no screening test has so far surpassed the practicality, affordability and effectiveness of tests for the presence of blood in faeces (faecal occult blood tests, FOBt). The results of several large FOBt-based randomised controlled trials provide the best clinical evidence to support their use in population-based CRC screening. This review considers the current options for CRC screening and the future for FOBt.

A service evaluation of the use of faecal immunochemical tests in symptomatic patients aged under 50 years presenting to primary care.

BACKGROUND: Most colorectal cancers (CRCs) occur in individuals aged over 50 years; however, the incidence in younger age groups is increasing. Diagnosis in younger patients is frequently delayed due to non-specific symptoms and the relative frequency of benign disease. There is a need to identify patients who warrant further investigation for CRC. This study reviewed whether a faecal haemoglobin (f-Hb) ≥10 µg Hb/g faeces measured by the faecal immunochemical test for f-Hb (FIT) was associated with CRC in a local primary care population aged under 50 years. METHODS: f-Hb results from symptomatic patients aged 18-49 years presenting to primary care during a 17-month period were extracted from local laboratory information systems. Colonoscopy lists were obtained from three local trusts. The Somerset Cancer Registry was searched to identify CRCs. f-Hb and outcomes were matched using NHS numbers. RESULTS: A total of 3119 patients were included (median age 41 years); 313 of 2682 patients with f-Hb <10 µg/g (11.7%) and 305 of 437 patients with f-Hb ≥10 µg/g (69.8%) underwent colonoscopy. Twelve CRCs were detected. At a cut-off of 10 µg/g, the positivity rate was 14.0%, sensitivity was 100% (75.8-100%), specificity was 86.3% (85.1-87.5%), positive predictive value (PPV) was 2.7% (2.5-3.0%) and negative predictive value (NPV) was 100%. At a cut-off of 150 µg/g, sensitivity was 83.3% (55.2-95.3%), specificity was 95.2% (94.4-95.9%), PPV was 6.2% (4.7-8.2%) and NPV was 99.9% (99.8-100%). CONCLUSION: Our data supports the use of FIT to triage patients aged under 50 years presenting to primary care with symptoms suggestive of CRCs.