Extending faecal immunochemical tests for haemoglobin (FIT) to all primary care patients with symptoms suggestive of colorectal cancer (CRC) could identify people who are likely to benefit from colonoscopy and facilitate earlier treatment. The aim of this work was to investigate the diagnostic accuracy of FIT across different analysers at different thresholds, as a single test or in duplicate (dual FIT).

This systematic review and meta-analysis searched 10 sources (December 2022). Diagnostic accuracy studies of HM-JACKarc, OC-Sensor, FOB Gold, QuikRead go, NS-Prime and four Immunodiagnostik (IDK) tests in primary care patients were included. Risk of bias was assessed (QUADAS-2). Statistical syntheses produced summary estimates of sensitivity and specificity at any chosen threshold for CRC, inflammatory bowel disease and advanced adenomas separately. Sensitivity analyses investigated reference standard and population type (high, low or all-risk). Subgroup analyses investigated patient characteristics (e.g. anaemia, age, sex, ethnicity).

Thirty-seven studies were included. At a threshold of 10 μg/g, pooled results for sensitivity and specificity (95% credible intervals) for CRC, respectively, were: HM-JACKarc (n = 16 studies) 89.5% (84.6%-93.4%) and 82.8% (75.2%-89.6%); OC-Sensor (n = 11 studies) 89.8% (85.9%-93.3%) and 77.6% (64.3%-88.6%); FOB Gold (n = 3 studies), 87.0% (67.3%-98.3%) and 88.4% (81.7%-94.2%). There were limited or no data on the other tests, dual FIT and relating to patient characteristics.

Test sensitivity at a threshold of 10 μg/g highlights a requirement for adequate safeguards in test-negative patients with ongoing symptoms. Further research is needed into the impact of patient characteristics and dual FIT.

Use of the faecal immunochemical test (FIT) to triage patients with iron deficiency (ID) for colonoscopy due to suspected colorectal cancer (CRC) may improve distribution of colonoscopic resources. We reviewed the diagnostic performance of FIT for detecting advanced colorectal neoplasia, including CRC and advanced pre-cancerous neoplasia (APCN), in patients with ID, with or without anaemia.

We performed a systematic review of three databases for studies comprising of patients with ID, with or without anaemia, completing a quantitative FIT within six months prior to colonoscopy, where test performance was compared against the reference standard colonoscopy. Random effects meta-analyses determined the diagnostic performance of FIT for advanced colorectal neoplasia.

Nine studies were included on a total of n=1761 patients with ID, reporting FIT positivity thresholds between 4-150 µg haemoglobin/g faeces. Only one study included a non-anaemic ID (NAID) cohort. FIT detected CRC and APCN in ID patients with 90.7 % and 49.3 % sensitivity, and 81.0 % and 82.4 % specificity, respectively. FIT was 88.0 % sensitive and 83.4 % specific for CRC in patients with ID anaemia at a FIT positivity threshold of 10 µg haemoglobin/g faeces.

FIT shows high sensitivity for advanced colorectal neoplasia and may be used to triage those with ID anaemia where colonoscopic resources are limited, enabling those at higher risk of CRC to be prioritised for colonoscopy. There is a need for further research investigating the diagnostic performance of FIT in NAID patients.

Use of faecal immunochemical testing (FIT) for symptomatic patients is increasing. FIT is recommended as a triage tool from primary care to the two-week wait (TWW) suspected cancer pathway, but there is still little known about patient attitudes.

The aim of this study was to explore patient opinions of FIT and how it might be applied in the TWW pathway.

A telephone survey was conducted for patients from the TWW pathway who had undergone both conventional colonic investigation and FIT. Five questions explored expectations, attitudes towards results and experience of the investigations using a Likert scale 1-5. Differences in opinion were compared using median and mode scores and visualised using bar charts.

One hundred and nine TWW patients agreed to answer the five questions. All had taken a stool sample for FIT, 50 underwent colonoscopy, 51 had a CT colonography and 8 underwent flexible sigmoidoscopy. Most patients (85%) scored 5 (completely satisfied) with these conventional colonic investigation methods they underwent for ruling out colorectal cancer (median 5). However, 30% of patients scored 5 (completely satisfied) if using a negative FIT to not require additional colonic investigation. The median score to perform FIT was 5 (very easy) compared with a median of 4 (easy) to undergo the other colonic investigations.

Symptomatic patients can perform FIT with little difficulty, and often would have been happy to avoid conventional colonic investigations with a negative result. However, shared decision-making should be employed to identify those who would be dissatisfied with relying on FIT for further investigation decisions.

A digital rectal examination (DRE) during routine assessment for patients with abdominal symptoms provides an opportunity to obtain faeces from the glove for faecal immunochemical testing (FIT). Here, we compared sampling via DRE to the standard faecal sampling by patients.

Patients were recruited to a prospective observational cohort study between July 2019 and March 2020. Patients provided a sample for the FOB Gold Wide^® which was compared to a further sample taken at clinic via DRE. Clinicians reported whether they obtained a 'good' sample filling all the grooves, a 'poor' sample filling some of the grooves or no faecal sample. Cohen's kappa was used to compare percentage agreement around a negative threshold of <10 μg haemoglobin/g of faeces. Sensitivity for serious bowel disease (SBD) was calculated.

Of 596 patients who underwent attempted DRE sampling, there were 258 (43.3%) 'good' samples, 117 (19.6%) 'poor' samples and 221 (37.1%) with no sample to wipe in the grooves. Cohen's kappa dropped from 0.70 to 0.30 for the 'good' and 'poor' samples, respectively. Of those with DRE samples and definitive diagnostic outcomes, the sensitivity for SBD dropped significantly from 76.0% to 41.7% between 'good' and 'poor' samples, respectively (p = 0.041).

A 'good' sample obtained by DRE provides comparable results to samples obtained by patients. This creates potential benefit in speed and ease of testing for patients. However, not all DRE sampling attempts are successful, and the clinician must be satisfied that enough faeces is obtained to wipe adequately into all grooves.

The UK National Institute for Health and Care Excellence (NICE), recommended in 2017 the use of the faecal immunochemical test (FIT) to guide investigations in patients presenting with NICE-defined low-risk symptoms suspicious for colorectal cancer (CRC). At that time, NICE did not recommend FIT use for high-risk symptoms. This is the first systematic review to evaluate the diagnostic accuracy of FIT in NICE-defined high and low-risk symptoms and was designed to inform the joint ACPGBI/BSG guidelines.

We performed a systematic literature review and meta-analysis. PROSPERO registration number CRD42021224674. Medline and EMBASE databases were searched from inception to 31st March 2022. We included studies recruiting adult patients presenting with suspected CRC symptoms in whom FIT was performed and diagnostic accuracy data for CRC detection could be derived at a limit of detection (LoD) and/or 10 µg haemoglobin/gram faeces threshold in four commonly used analysers. FIT performance was assessed for high-risk, low-risk and individual symptoms where possible. Bivariate meta-analysis was performed where study numbers allowed.

Thirty-one studies (79566 patients) met inclusion criteria. At 10 µg/g, for "all symptoms" (n = 35,945) sensitivity and specificity were 91.0% (95% CI: 88.9, 92.7) and 75.2% (95% CI: 69.6, 80.1); for "high-risk" symptoms (n = 18,264), 88.7% (95% CI: 84.4, 92.0) and 78.5% (95% CI: 73.0, 83.2); and for "low-risk" symptoms (n = 2161), 88.7% (95% CI: 78.1, 95.3) and 88.5% (95% CI: 87.1, 89.9), respectively. At LoD, for "all symptoms" (n = 26,056) sensitivity and specificity were 94.7% (95% CI: 90.5, 97.1) and 66.5% (95% CI: 58.7, 73.6); for "high-risk" symptoms (n = 16,768), 92.8% (95% CI: 86.4, 96.3) and 70.3% (95% CI: 66.5, 73.8); and for "low-risk" symptoms (n = 2082), 94.7% (95% CI: 85.4, 98.9) and 71.9% (95% CI: 69.9, 73.9), respectively. Summary estimates were similar across different analysers.

FIT sensitivity for CRC detection is maximised at the LoD; its performance is similar in high and low-risk symptoms, and across different analysers where a common threshold is used. FIT performance for CRC detection is adequate and transferrable to clinical diagnostic pathways.

This review was part-funded by NHS England awarded to RM Partners. RB and RC were funded by research fellowships awarded by Croydon University Hospital.

Faecal immunochemical testing (FIT) has a high sensitivity for the detection of colorectal cancer (CRC). In a symptomatic population FIT may identify those patients who require colorectal investigation with the highest priority. FIT offers considerable advantages over the use of symptoms alone, as an objective measure of risk with a vastly superior positive predictive value for CRC, while conversely identifying a truly low risk cohort of patients. The aim of this guideline was to provide a clear strategy for the use of FIT in the diagnostic pathway of people with signs or symptoms of a suspected diagnosis of CRC. The guideline was jointly developed by the Association of Coloproctology of Great Britain and Ireland/British Society of Gastroenterology, specifically by a 21-member multidisciplinary guideline development group (GDG). A systematic review of 13 535 publications was undertaken to develop 23 evidence and expert opinion-based recommendations for the triage of people with symptoms of a suspected CRC diagnosis in primary care. In order to achieve consensus among a broad group of key stakeholders, we completed an extended Delphi of the GDG, and also 61 other individuals across the UK and Ireland, including by members of the public, charities and primary and secondary care. Seventeen research recommendations were also prioritised to inform clinical management.

This review evaluated the utility of single quantitative faecal immunochemical test (FIT) as a triaging tool for patients with symptoms of possible colorectal cancer, the effect of symptoms on FIT accuracy, and the impact of triaging incorporating FIT on service provision.

Five databases were searched. Meta-analyses of the extracted FIT sensitivities and specificities for detection of colorectal cancer at reported f-Hb thresholds were performed. Secondary outcomes included sensitivity and specificity of FIT for advanced colorectal neoplasia and serious bowel disease. Subgroup analysis by FIT brand and symptoms was undertaken.

Fifteen prospective cohort studies, including 28 832 symptomatic patients were included. At the most commonly reported f-Hb positivity threshold of ≥ 10 µg Hb/g faeces (n=13), the summary sensitivity was 88.7% (95% c.i. 85.2 to 91.4) and the specificity was 80.5% (95% c.i. 75.3 to 84.8) for colorectal cancer. At lower limits of detection of ≥ 2 µg Hb/g faeces, the summary sensitivity was 96.8% (95% c.i. 91.0 to 98.9) and the specificity was 65.6% (95% c.i. 59.0 to 71.6). At the upper f-Hb positivity thresholds of ≥ 100 µg Hb/g faeces and ≥ 150 µg Hb/g faeces, summary sensitivities were 68.1% (95% c.i. 59.2 to 75.9) and 66.3% (95% c.i. 52.2 to 78.0), with specificities of 93.4% (95% c.i. 91.3 to 95.1) and 95.1% (95% c.i. 93.6 to 96.3) respectively. FIT sensitivity was comparable between different assay brands. FIT sensitivity may be higher in patients reporting rectal bleeding.

Single quantitative FIT at lower f-Hb positivity thresholds can adequately exclude colorectal cancer in symptomatic patients and provides a data-based approach to prioritization of colonoscopy resources.