Application of NICE guideline NG12 to the initial assessment of patients with lower gastrointestinal symptoms: not FIT for purpose?

The impact of primary-care led, faecal immunochemical test-based, triage of new-onset colorectal symptoms on time to diagnosis of colorectal cancer-An observational study

AIM

Since December 2015, a faecal immunochemical test (FIT) has been provided to primary care in NHS Tayside as an adjunct to clinical acumen in the assessment of new-onset bowel symptoms. The aim of this work was to assess the impact of this approach on time to diagnosis of colorectal cancer (CRC).

METHOD

NHS Tayside Cancer audit data from January 2013 to December 2019 were reviewed to identify all CRC patients diagnosed via the primary-care referral pathway for a period before and after the introduction of FIT. Their electronic patient records were accessed and date of referral and any contemporaneous FIT and full blood count (FBC) result were recorded. Time from referral to diagnosis of CRC was calculated for each patient and compared between subgroups.

RESULTS

The study cohort consisted of 959 patients: 378 and 581 from the time periods before and after the introduction of FIT, respectively. The median time to diagnosis before FIT was 30 days [interquartile range (IQR) 16-57 days] versus 25 days (IQR 14-47 days) following the introduction of FIT (p = 0.006). Following the introduction of FIT, patients who completed a FIT had a median of time to diagnosis of 23 days (IQR 14-43 days) compared with 30 days (IQR 16-62 days) for patients not completing a FIT (p = 0.019). FBC results were available for 97.5% of FIT patients to aid safety-netting of patients with a low or undetectable faecal haemoglobin concentration.

CONCLUSION

The introduction of FIT-based triage of new bowel symptoms in primary care as an adjunct to clinical acumen is associated with a reduced time to CRC diagnosis.

Colonoscopic cancer detection rate: a new performance measure - is it FIT for purpose?

Introduction

Gastrointestinal symptoms correlate poorly with cancer diagnosis. A faecal immunochemical test (FIT) result of ≥10 µg has high sensitivity and negative predictive value for colorectal cancer (CRC) detection. An FIT-based diagnostic pathway may lead to more effective resource utilisation. We aimed to use National Endoscopy Database (NED) data to create a new colonoscopy performance measure, cancer detection rate (CDR) to assess the appropriate identification of target populations for colonoscopy; then to use CDR to assess the impact of implementing an FIT-based referral pathway locally.

Methods

NED data were analysed to compare local diagnostic colonoscopic CDR in 2019 (prepathway revision) and 2021 (postpathway revision), benchmarked against overall national CDR for the same time frames.

Results

1, 123, 624 NED diagnostic colonoscopies were analysed. Locally, there was a significant increase in CDR between 2019 and 2021, from 3.01% (2.45%-3.47%) to 4.32% (3.69%-4.95%), p=0.003. The CDR increase was due to both a 10% increase in the number of CRCs detected and a 25% reduction in the number of diagnostic colonoscopies performed. Nationally, there was a smaller, but significant, increase in CDR from 2.02% (1.99%-2.07%) to 2.33% (2.29%-2.37%), p<0.001. The rate of increase in CDR% between 2019 and 2021 was significantly different locally compared with nationally.

Conclusion

Our study indicates that the introduction of a robustly vetted FIT-based algorithm to determine whether diagnostic colonoscopy is required, is effective in increasing the colonoscopic CDR. Moreover, CDR appears to be a meaningful performance metric that can be automatically calculated through NED, enabling monitoring of the quality of referral and vetting pathways.

Do risk scores improve use of faecal immunochemical testing for haemoglobin in symptomatic patients in primary care?

AIM

Faecal immunochemical testing (FIT) is used in the detection of colorectal cancer (CRC). FIT is invariably used at a single faecal haemoglobin (f-Hb) concentration threshold. The aim of this observational study was to explore risk scoring models (RSMs) with f-Hb and other risk factors for CRC in symptomatic patients attending primary care, potentially speeding diagnosis and saving endoscopy resources.

METHOD

Records of patients completing FIT were linked with The Scottish Cancer Registry and with other databases with symptoms, full blood count and demographic variables, and randomized into derivation and validation cohorts. Stepwise multivariable logistic regression created RSMs assessed in the validation cohort.

RESULTS

Of 18 805 unique patients, 9374 and 9431 were in the derivation and validation cohorts, respectively: f-Hb, male sex, increasing age, iron deficiency anaemia and raised systemic immune inflammation index created the final RSM. A risk score threshold of ≥2.363, generating the same number of colonoscopies as a f-Hb threshold of ≥10 μg Hb/g gave improved sensitivity for CRC in both cohorts. A RSM which excluded f-Hb was used to investigate the effect of raising the f-Hb threshold from ≥10 to ≥20 μg Hb/g in those with a low risk score. This approach would have generated 234 fewer colonoscopies but missed four CRCs.

CONCLUSION

The RSM conferred no significant benefit to patients with very low f-Hb and CRC. Alternative strategies combining FIT with other variables may be more appropriate for safety-netting of symptomatic patients. Further work to develop and investigate the value of RSM for significant bowel disease other than CRC may also be beneficial.

Evaluation of 13,466 Fecal Immunochemical Tests in Patients Attending Primary Care for High- and Low-Risk Gastrointestinal Symptoms of Colorectal Cancer

AIM/OBJECTIVE

Quantitative fecal immunochemical tests (FIT) were recommended by NICE for patients in primary care presenting with low-risk symptoms of colorectal cancer (CRC). FIT is more accurate in the detection of CRC than symptom criteria. Despite this, CRC still occurs with a negative FIT and the importance of safety netting for patients with severe or persistent symptoms is paramount. We aimed to evaluate the utilization and accuracy of FIT for CRC in low and high-risk symptom groups presenting to primary care, the effectiveness of safety netting in primary care, referral practices with FIT utilization for symptomatic patients and the clinical features of FIT negative patients with CRC.

MATERIALS AND METHODS

Medical records and databases of all patients undertaking a FIT sample in the Herts Valleys CCG between June 2019 and November 2021 were reviewed. 13,466 consecutive FIT samples were requested for 12,231 patients between June 2019 and November 2021.

RESULTS

Analysis of diagnostic accuracy was undertaken for the first 5341 patients with a minimum of 12 months follow up. Sensitivity for CRC, in FIT ≥ 4 µg Hb/g, ≥ 10 µg Hb/g and ≥ 100 µg Hb/g was 93% (95% CI 85-98%), 91% (95% CI 82-96%) and 72% (95% CI 60-81%) with a number needed to investigate of 36, 19 and 6, respectively.

CONCLUSION

A FIT ≥ 10 µg Hb/g in conjunction with ongoing GP clinical concern within 8 weeks had a sensitivity for CRC of 97% (95% CI 90-100%), a PPV of 3.6% (95% CI 3.4-3.7%) and a number needed to investigate to detect one CRC of 28.

The diagnostic accuracy of the faecal immunohistochemical test in identifying significant bowel disease in a symptomatic population

AIM

Provisional research on the faecal immunohistochemical test (FIT) for symptomatic colorectal patients has shown a high negative predictive value but has lacked long-term patient follow-up, raising the possibility of missed diagnoses of colorectal cancer (CRC). The aim of this work is to describe the long-term diagnostic accuracy of the FIT for CRC and significant bowel disease (SBD) in a symptomatic population in NHS Lanarkshire.

METHOD

From October 2016 to February 2019, all primary care referrals of symptomatic colorectal patients in NHS Lanarkshire were asked to provide a FIT. The baseline demographics, investigations and diagnoses for each patient were prospectively completed until February 2021. A FIT result of ≥10 μg haemoglobin (Hb)/g faeces was considered to be positive.

RESULTS

A total of 5250 patients were identified (median age 62 years; 46% male; median follow-up 31 months) with 65.1% (3418) being FIT negative. The SBD rate was 6.2% and the CRC rate was 2.9% (151). The SBD rate was significantly higher in the FIT-positive group (13.8% vs. 2.2%; p < 0.001) and 32.9% of patients with FIT ≥ 400 μg Hb/g had SBD. The sensitivity of FIT ≥ 10 μg Hb/g for CRC was 87.4% and for SBD it was 76.9%. Specificity was 66.6% and 66.7%, and the negative-predictive value was 99.4% and 97.7%, respectively. Sensitivity for CRC could theoretically be increased to 94.8% if FIT-negative patients were to undergo flexible sigmoidoscopy.

CONCLUSION

A FIT-only referral pathway for symptomatic colorectal patients will miss over 12% of cancers and over 23% of SBD. Theoretically, combining FIT-negative patients with flexible sigmoidoscopy increases the sensitivity for CRC. The FIT offers a mechanism for prioritizing patient access to investigations, particularly in resource-limited areas; however, further work to identify FIT-negative patients diagnosed with CRC is required.

Faecal immunochemical test for patients with 'high-risk' bowel symptoms: a large prospective cohort study and updated literature review

Background

We evaluated whether faecal immunochemical testing (FIT) can rule out colorectal cancer (CRC) among patients presenting with ‘high-risk’ symptoms requiring definitive investigation.

Methods

Three thousand five hundred and ninety-six symptomatic patients referred to the standard urgent CRC pathway were recruited in a multi-centre observational study. They completed FIT in addition to standard investigations. CRC miss rate (percentage of CRC cases with low quantitative faecal haemoglobin [f-Hb] measurement) and specificity (percentage of patients without cancer with low f-Hb) were calculated. We also provided an updated literature review.

Results

Ninety patients had CRC. At f-Hb < 10 µg/g, the miss rate was 16.7% (specificity 80.1%). At f-Hb < 4 µg/g, the miss rate was 12.2% (specificity 73%), which became 3.3% if low FIT plus the absence of anaemia and abdominal pain were considered (specificity 51%). Within meta-analyses of 9 UK studies, the pooled miss rate was 7.2% (specificity 74%) for f-Hb < 4 µg/g.

Discussion

FIT alone as a triage tool would miss an estimated 1 in 8 cases in our study (1 in 14 from meta-analysis), while many people without CRC could avoid investigations. FIT can focus secondary care diagnostic capacity on patients most at risk of CRC, but more work on safety netting is required before incorporating FIT triage into the urgent diagnostic pathway.

The Fast Track FIT study: diagnostic accuracy of faecal immunochemical test for haemoglobin in patients with suspected colorectal cancer

BACKGROUND

The faecal immunochemical test (FIT) is now available to support clinicians in the assessment of patients at low risk of colorectal cancer (CRC) and within the bowel cancer screening programme.

AIM

To determine the diagnostic accuracy of FIT for CRC and clinically significant disease in patients referred as they were judged by their GP to fulfil National Institute for Health and Care Excellence guideline 12 (NG12) criteria for suspected CRC.

DESIGN AND SETTING

Patients referred from primary care with suspected CRC, meeting NG12 criteria, to 12 secondary care providers in Yorkshire and Humber were asked to complete a FIT before investigation.

METHOD

The diagnostic accuracy of FIT based on final diagnosis was evaluated using receiver operating characteristics analysis. This permitted a statistically optimal cut-off value for FIT to be determined based on the maximisation of sensitivity and specificity. Clinicians and patients were blinded to the FIT results.

RESULTS

In total, 5040 patients were fully evaluated and CRC was detected in 151 (3.0%). An optimal cut-off value of 19 µg Hb/g faeces for CRC was determined, giving a sensitivity of 85.4% (95% confidence interval [CI] = 78.8% to 90.6%) and specificity of 85.2% (95% CI = 84.1% to 86.2%). The negative predictive value at this cut-off value was 99.5% (95% CI = 99.2% to 99.7%) and the positive predictive value 15.1% (95% CI = 12.8% to 17.7%). Sensitivity and specificity of FIT for CRC and significant premalignant polyps at this cut-off value were 62.9% (95% CI = 57.5% to 68.0%) and 86.4% (95% CI = 85.4% to 87.4%), respectively; and when including all organic enteric disease were 35.7% (95% CI = 32.9% to 38.5%) and 88.6% (95% CI = 87.5% to 89.6%), respectively.

CONCLUSION

FIT used in patients fulfilling NG12 criteria should allow for a more personalised CRC risk assessment. FIT should permit effective, patient-centred decision-making to inform the need for, type, and timing of further investigation.

Clinical guidelines “Chronic diarrhea in adults”

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Yield of colorectal cancer at colonoscopy according to faecal haemoglobin concentration in symptomatic patients referred from primary care

AIM

Lower gastrointestinal (GI) symptoms are poor predictors of colorectal cancer (CRC). The aim of this study was to examine the diagnostic yield of colonoscopy by faecal haemoglobin (f-Hb) concentration in symptomatic patients assessed in primary care by faecal immunochemical testing (FIT).

METHOD

In three Scottish NHS Boards, FIT kits (HM-JACKarc, Hitachi Chemical Diagnostics Systems Co., Ltd, Tokyo, Japan) were used by general practitioners to guide referrals for patients with lower GI symptoms (laboratory data studied for 12 months from December 2015 onwards in Tayside, 18 months from June 2018 onwards in Fife and 5 months from September 2018 onwards in Greater Glasgow and Clyde). Cases of CRC diagnosed at colonoscopy were ascertained from colonoscopy and pathology records.

RESULTS

Four thousand eight hundred and forty one symptomatic patients who underwent colonoscopy after FIT submission were included. Of the 2166 patients (44.7%) with f-Hb <10 µg Hb/g faeces (µg/g), 14 (0.6%) were diagnosed with CRC, with a number needed to scope (NNS) of 155. Of the 2675 patients (55.3%) with f-Hb ≥10 µg/g, 252 were diagnosed with CRC (9.4%) with a NNS of 11. Of the 705 patients with f-Hb ≥400 µg/g, 158 (22.4%) were diagnosed with CRC with a NNS of 5. Over half of those diagnosed with CRC with f-Hb <10 µg/g had coexisting anaemia.

CONCLUSION

Symptomatic patients with f-Hb ≥10 µg/g should undergo further investigation for CRC, while higher f-Hb concentrations could be used to triage for urgency during the COVID-19 recovery phase. Patients with f-Hb <10 µg/g and without anaemia are very unlikely to be diagnosed with CRC and the majority need no further investigation.

Diagnostic performance of a faecal immunochemical test for patients with low-risk symptoms of colorectal cancer in primary care: an evaluation in the South West of England

BACKGROUND

The faecal immunochemical test (FIT) was introduced to triage patients with low-risk symptoms of possible colorectal cancer in English primary care in 2017, underpinned by little primary care evidence.

METHODS

All healthcare providers in the South West of England (population 4 million) participated in this evaluation. 3890 patients aged ≥50 years presenting in primary care with low-risk symptoms of colorectal cancer had a FIT from 01/06/2018 to 31/12/2018. A threshold of 10 μg Hb/g faeces defined a positive test.

RESULTS

Six hundred and eighteen (15.9%) patients tested positive; 458 (74.1%) had an urgent referral to specialist lower gastrointestinal (GI) services within three months. Forty-three were diagnosed with colorectal cancer within 12 months. 3272 tested negative; 324 (9.9%) had an urgent referral within three months. Eight were diagnosed with colorectal cancer within 12 months. Positive predictive value was 7.0% (95% CI 5.1-9.3%). Negative predictive value was 99.8% (CI 99.5-99.9%). Sensitivity was 84.3% (CI 71.4-93.0%), specificity 85.0% (CI 83.8-86.1%). The area under the ROC curve was 0.92 (CI 0.86-0.96). A threshold of 37 μg Hb/g faeces would identify patients with an individual 3% risk of cancer.

CONCLUSIONS

FIT performs exceptionally well to triage patients with low-risk symptoms of colorectal cancer in primary care; a higher threshold may be appropriate in the wake of the COVID-19 crisis.

Faecal immunochemical testing in symptomatic patients to prioritize investigation: diagnostic accuracy from NICE FIT Study

BACKGROUND

This study investigated whether a quantitative faecal immunochemical test (FIT) could be used to select patients with either high- or low-risk symptoms of colorectal cancer for urgent investigation.

METHODS

A double-blinded diagnostic accuracy study was conducted in 50 hospitals in England between October 2017 and December 2019. Patients were eligible for inclusion if they had been referred to secondary care with suspected colorectal cancer symptoms meeting national criteria for urgent referral and triaged to investigation with colonoscopy.

RESULTS

The study included 9822 patients, of whom 7194 (73.2 per cent) had high-risk symptoms, 1994 (20.3 per cent) low-risk symptoms, and 634 (6.5 per cent) had other symptoms warranting urgent referral. In patients with high-risk symptoms, the sensitivity of FIT for colorectal cancer at cut-off values of 2 and 10 μg haemoglobin per g faeces was 97.7 (95 per cent c.i. 95.0 to 99.1) and 92.2 (88.2 to 95.2) per cent respectively, compared with 94.3 (84.3 to 98.8) and 86.8 (74.7 to 94.5) per cent in patients with low-risk symptoms at the same cut-off points. At cut-off values of 2, 10, and 150 μg/g, the positive predictive value for colorectal cancer was 8.9, 16.2, and 30.5 per cent respectively for those with high-risk symptoms, and 8.4, 16.9, and 35.5 per cent for those with low-risk symptoms.

CONCLUSION

FIT safely selects patients with high or low risk symptoms of colorectal cancer for investigation.

Accuracy of faecal immunochemical testing in patients with symptomatic colorectal cancer

BACKGROUND

The aim of this study was to determine the diagnostic accuracy of the faecal immunochemical test (FIT) for detecting colorectal cancer in symptomatic patients.

METHODS

This was a prospective study of patients with bowel symptoms. Stool samples were collected during rectal examination. The HM-JACKarc assay (Kyowa Medex, Tokyo, Japan) was used to quantify faecal haemoglobin (Hb); positive results were those with at least 10 μg Hb/g faeces. Two-by-two tables and receiver operating characteristic (ROC) curve analysis were used to determine diagnostic accuracy; χ2 and Mann-Whitney U tests were used to compare other parameters.

RESULTS

A total of 928 patients were included (M : F ratio 1 : 1·5; median age 72 (i.q.r. 64-80) years). The overall prevalence of colorectal cancer was 5·1 per cent. The FIT had sensitivity of 85·1 per cent, specificity of 83·5 per cent, positive predictive value of 22·6 per cent and negative predictive value of 99·0 per cent. ROC analysis of FIT for diagnosing colorectal cancer gave an area under the curve value of 0·89 (95 per cent c.i. 0·84 to 0·94). Significant bowel pathology was detected more frequently in FIT-positive patients (35·1 per cent versus 7·1 per cent in FIT-negative patients; P < 0·001). There were sex differences in FIT positivity (23·7 per cent in men versus 17·4 per cent in women; P = 0·019); the sensitivity of FIT for colorectal cancer in women was also low. False-negative FIT results were found mainly in women referred with iron-deficiency anaemia, who were found to have caecal cancer.

CONCLUSION

FIT effectively excluded colorectal cancer in symptomatic patients. Integration of FIT into the diagnostic pathway for colorectal cancer would direct resources appropriately to patients with a greater likelihood of having the disease.

Faecal immunochemical testing for adults with symptoms of colorectal cancer attending English primary care: a retrospective cohort study of 14 487 consecutive test requests

BACKGROUND

Faecal immunochemical testing (FIT) is recommended by the National Institute for Health and Care Excellence (NICE) to triage symptomatic primary care patients for further investigation of colorectal cancer.

AIM

To ascertain the diagnostic performance of FIT in symptomatic adult primary care patients.

METHODS

Faecal samples from routine primary care practice in Oxfordshire, UK were analysed using the HM-JACKarc FIT method between March 2017 and March 2020. Clinical details were recorded. Patients were followed for up to 36 months in linked hospital records for evidence of benign and serious (colorectal cancer, high-risk adenomas and bowel inflammation) colorectal disease. The diagnostic accuracy of FIT is reported by gender, age group and FIT threshold.

RESULTS

In 9896 adult patients with at least 6-month follow-up, a FIT result ≥10 µg Hb/g faeces had a sensitivity for colorectal cancer of 90.5% (95% CI 84.9%-96.1%), specificity 91.3% (90.8%-91.9%), positive predictive value (PPV) 10.1% (8.15%-12.0%) and negative predictive value (NPV) 99.9% (99.8%-100.0%). The PPV and specificity for serious colorectal disease were higher and the sensitivity and NPV lower than for colorectal cancer alone. The area under the curve for all adults did not change substantially by gender or by increasing the minimum age of testing. Using ≥10 µg Hb/g faeces, 10% of adults would be investigated to detect 91% of cancers, a number needed to scope of ten to detect one cancer. Using ≥7, ≥50 and ≥150 µg Hb/g faeces, 11%, 4% and 3% of adults would be investigated, and 91%, 74% and 54% cancers detected, respectively.

CONCLUSION

A FIT threshold of ≥10 µg Hb/g faeces would be appropriate to triage adult patients presenting to primary care with symptoms of serious colorectal disease. FIT may be used to reprioritise patients referred with colorectal cancer symptoms whose investigations have been delayed by the COVID-19 pandemic.

Impact of the faecal immunochemical test on colorectal cancer survival

Background

There is already evidence that the faecal immunochemical test (FIT) is a useful tool for the diagnosis of colorectal cancer (CRC) that helps to identify symptomatic patients requiring early colonoscopy. Although the recommendation to use FIT is widely accepted, there are no data concerning whether this strategy improves patient survival.The objective was to assess whether the survival is higher if CRC patients have been first diagnosed by FIT (as compared with the rest of patients with CRC).

Methods

We identified all cases of CRC diagnosed between 2009 and 2016 in Donostialdea (Spain), excluding all the CRC detected in population screening. We focused on symptomatic patients. One thousand five hundred twenty-seven cases of CRC were divided into two groups based on the route to diagnosis: group 1: individuals who tested positive in a FIT during the year before diagnosis, and group 2: others.Survival was assessed by Kaplan-Meier estimation, and with the log-rank test. A Cox regression model was used to adjust for differences between groups due to other variables associated with survival.

Results

One thousand nine hundred sixty-seven cases of invasive CRC were identified, of which 22.4% were detected in population screening. Of the 1527 cases diagnosed in symptomatic patients, 317 patients had undergone a FIT in the year before the diagnosis of CRC. In 279 cases(18.3%), the result had been positive and this was the first step towards their CRC diagnosis (group 1). Group 2 was composed of the 1248 cases of CRC (81.7%). Considering these cases, 1210 patients with CRC did not undergo any FIT while 38 patients presented a negative result in the year before the diagnosis. The rate of early-stage disease (stage I or II) was higher in group 1 (51.3% vs 45.5% in group 2) (p = 0.04). Furthermore, the 3-year survival was longer in group 1 (72% vs 59% in group 2) (HR 1.50; 95% CI 1.22–1.84).The variables independently associated with worse survival were: group 2, age > 70 years and stage at the moment of diagnosis.

Conclusions

The use of FIT as a diagnostic strategy in symptomatic patients may improve survival in CRC. Nonetheless,FIT is still not widely used in our region.

Diagnostic accuracy of a quantitative faecal immunochemical test vs. symptoms suspected for colorectal cancer in patients referred for colonoscopy

Objective: Determine diagnostic accuracy of a quantitative faecal immunochemical haemoglobin test (QuikRead go^® FIT, Orion Diagnostica Oy) in symptomatic patients referred for colonoscopy, at various cut-offs and for one or two tests.Methods: Patients referred to four endoscopy units in mid-Sweden between 2013 and 2017 provided information on lower abdominal symptoms and faecal samples from two separate days prior to colonoscopy.Results: In all, 5.4% (13/242) patients had colorectal cancer (CRC). For one FIT at cut-off 10 µg Hb/g faeces, sensitivity for CRC was 92% (95% CI 78-100%) and specificity 77% (95% CI 72-83%); equal to 74%; 95% CI 68-80 (178/242) colonoscopies potentially avoidable and one CRC missed. Based on the maximal outcome of two FITs, sensitivity was 100%, specificity 71% (66-77%) and 68%; 95% CI 62-74 (160/237) colonoscopies potentially avoidable. Among 17% (42/242) patients with one FIT of >200 µg Hb/g faeces, 85% (11/13) had CRC. Positive predictive values of FIT varied 16.9-26.2% depending on cut-off and one or two FITs, whereas NPVs were 99% and above in all scenarios.In 60 patients reporting rectal bleeding, one FIT at cut-off 10 µg Hb/g discriminated well between CRC and other conditions (p = .001). In regression models, FIT was more important than age, sex and all symptoms.Conclusion: One or two FITs in symptomatic patients referred for colonoscopy imply powerful risk stratification abilities for CRC, even among patients reporting rectal bleeding. Larger studies in various settings will clarify how to make the best use of this opportunity. Trial registration: Clinicaltrails.gov NCT02491593.

Appraisal of the faecal haemoglobin, age and sex test (FAST) score in assessment of patients with lower bowel symptoms: an observational study

Background

Many patients present in primary care with lower bowel symptoms, but significant bowel disease (SBD), comprising colorectal cancer (CRC), advanced adenoma (AA), or inflammatory bowel disease (IBD), is uncommon. Quantitative faecal immunochemical tests for haemoglobin (FIT), which examine faecal haemoglobin concentrations (f-Hb), assist in deciding who would benefit from colonoscopy. Incorporation of additional variables in an individual risk-score might improve this approach. We investigated if the published f-Hb, age and sex test score (FAST score) added value.

Methods

Data from the first year of routine use of FIT in primary care in one NHS Board in Scotland were examined: f-Hb was estimated using one HM-JACKarc FIT system (Kyowa Medex Co., Ltd., Tokyo, Japan) with a cut-off for positivity ≥10 μg Hb/g faeces. 5660 specimens were received for analysis in the first year. 4072 patients were referred to secondary care: 2881 (70.6%) of these had returned a FIT specimen. Of those referred, 1447 had colonoscopy data as well as the f-Hb result (group A): 2521 patients, also with f-Hb, were not immediately referred (group B). The FAST score was assessed in both groups.

Results

1196 (41.7%) of patients who returned a specimen for FIT analysis had f-Hb ≥10 μg Hb/g faeces. In group A, 252 of 296 (85.1%) with SBD had f-Hb > 10 μg Hb/g faeces, as did 528 of 1151 (45.8%) without SBD. Using a FAST score > 2.12, which gives high clinical sensitivity for CRC, only 1143 would have been referred for colonoscopy (21.0% reduction in demand): 286 of 296 (96.6%) with SBD had a positive FAST score, as did 857 of 1151 (74.5%) without SBD. However, one CRC, five AA and four IBD would have been missed. In group B, although 95.2% had f-Hb < 10 μg Hb/g faeces, 1371 (53.7%) had FAST score ≥ 2.12: clinical rationale led to only 122 of group B completing subsequent bowel investigations: a FAST score > 2.12 was found in 13 of 15 (86.7%) with SBD.

Conclusions

The performance characteristics of the FAST score did not seem to enhance the utility of f-Hb alone. Locally-derived formulae might confer desired benefits.

Experience of adopting faecal immunochemical testing to meet the NICE colorectal cancer referral criteria for low-risk symptomatic primary care patients in Oxfordshire, UK

OBJECTIVE

To compare the diagnostic performance of guaiac faecal occult blood (gFOB) testing with faecal immunochemical test (FIT) in a low-risk symptomatic primary care population to provide objective data on which to base local referral guidelines.

DESIGN

Stool samples from routine primary care practice sent for faecal occult blood testing were analysed by a standard gFOB method and the HM-JACKarc FIT between January and March 2016. Symptoms described on the test request were recorded. Patients were followed up over 21 months for evidence of serious gastrointestinal pathology including colorectal adenocarcinoma.

RESULTS

In 238 patients, the sensitivity and specificity for colorectal adenocarcinoma detection using gFOB were 85.7% and 65.8%, respectively, compared with 85.7% and 89.2% for FIT. The positive predictive value (PPV) for gFOB was 7.1% and negative predictive value (NPV) was 99.3%. Comparatively, the PPV for FIT was 19.4% and NPV 99.5%. The improved performance of FIT over gFOB was due to a lower false positive rate (10.8 vs 34.2, p≤0.01) with no increase in the false negatives rate. For any significant colorectal disease, the PPV for FIT increased to 35.5% with a reduction in NPV to 95.7%.

CONCLUSION

In this low-risk symptomatic patient group, the proportion of samples considered positive by FIT was considerably lower than gFOB with the same rate of colorectal adenocarcinoma detection. One in three of those with positive FIT had a significant colorectal disease. This supports National Institute of Health and Care Excellence recommendation that FIT can be reliably used as a triage test in primary care without overburdening endoscopy resources.

High-risk symptoms and quantitative faecal immunochemical test accuracy: Systematic review and meta-analysis

BACKGROUND

The quantitative faecal immunochemical test for haemoglobin (FIT) has been revealed to be highly accurate for colorectal cancer (CRC) detection not only in a screening setting, but also in the assessment of patients presenting lower bowel symptoms. Therefore, the National Institute for Health and Care Excellence has recommended the adoption of FIT in primary care to guide referral for suspected CRC in low-risk symptomatic patients using a 10 µg Hb/g faeces threshold. Nevertheless, it is unknown whether FIT´s accuracy remains stable throughout the broad spectrum of possible symptoms.

AIM

To perform a systematic review and meta-analysis to assess FIT accuracy for CRC detection in different clinical settings.

METHODS

A systematic literature search was performed using MEDLINE and EMBASE databases from inception to May 2018 to conduct a meta-analysis of prospective studies including symptomatic patients that evaluated the diagnostic accuracy of quantitative FIT for CRC detection. Studies were classified on the basis of brand, threshold of faecal haemoglobin concentration for a positive test result, percentage of reported symptoms (solely symptomatic, mixed cohorts) and CRC prevalence (< 2.5%, ≥ 2.5%) to limit heterogeneity and perform subgroup analysis to assess the influence of clinical spectrum on FIT´s accuracy to detect CRC.

RESULTS

Fifteen cohorts including 13073 patients (CRC prevalence 0.4% to 16.8%) were identified. Pooled estimates of sensitivity for studies using OC-Sensor at 10 µg Hb/g faeces threshold (n = 10400) was 89.6% [95% confidence interval (CI): 82.7% to 94.0%). However, pooled estimates of sensitivity for studies formed solely by symptomatic patients (n = 4035) and mixed cohorts (n = 6365) were 94.1% (95%CI: 90.0% to 96.6%) and 85.5% (95%CI: 76.5% to 91.4%) respectively (P < 0.01), while there were no statistically significant differences between pooled sensitivity of studies with CRC prevalence < 2.5% (84.9%, 95%CI: 73.4% to 92.0%) and ≥ 2.5% (91.7%, 95%CI: 83.3% to 96.1%) (P = 0.25). At the same threshold, OC-Sensor® sensitivity to rule out any significant colonic lesion was 78.6% (95%CI: 75.6% to 81.4%). We found substantial heterogeneity especially when assessing specificity.

CONCLUSION

The results of this meta-analysis confirm that, regardless of CRC prevalence, quantitative FIT is highly sensitive for CRC detection. However, FIT ability to rule out CRC is higher in studies solely including symptomatic patients.

Do other variables add value to assessment of the risk of colorectal disease using faecal immunochemical tests for haemoglobin?

Background

Faecal immunochemical tests for haemoglobin have been recommended to assist in assessment of patients presenting in primary care with lower bowel symptoms. The aim was to assess if, and which, additional variables might enhance this use of faecal immunochemical tests.

Methods

Faecal immunochemical test analysis has been a NHS Tayside investigation since December 2015. During the first year, 993 patients attending colonoscopy were invited to complete a detailed questionnaire on demographic background, symptoms, smoking status, alcohol use, dietary fibre, red and processed meat intake, physical activity, sitting time, dietary supplement use, family history of colorectal cancer, adenoma, inflammatory bowel disease and diabetes. Significant bowel disease was classified as colorectal cancer, advanced adenoma or inflammatory bowel disease.

Results

A total of 470 (47.3%) invitees agreed to complete the questionnaire and 408 (41.1%) did. Unadjusted odds ratios for the presence of significant bowel disease compared with undetectable faecal haemoglobin increased with increasing faecal haemoglobin and for faecal haemoglobin 10–49, 50–199, 200–399 and ⩾400 μg Hb/g faeces were 0.95 (95% CI: 0.16–5.63), 2.47 (0.55–1.03), 6.30 (1.08–36.65) and 18.90 (4.22–84.62), respectively. Rectal bleeding and family history of polyps were the only other variables with statistically significant ( P < 0.05) odds ratios greater than 1.00, being 1.88 (1.13–3.17) and 2.93 (1.23–6.95), respectively. Odds ratios adjusted for all other variables showed similar associations, but only faecal haemoglobin and family history of polyps had significant associations.

Conclusions

Faecal haemoglobin is the most important factor to be considered when deciding which patients presenting in primary care with lower bowel symptoms would benefit most from referral for colonoscopy.

Faecal immunochemical tests for haemoglobin (FIT) in the assessment of patients with lower abdominal symptoms: current controversies

Faecal immunochemical tests for haemoglobin (FIT), as an adjunct to clinical information, assist in the triage of patients presenting in primary care with lower abdominal symptoms. Controversy remains regarding whether and which qualitative and quantitative FIT can be used, which groups of patients would benefit most from FIT, whether FIT should be done in primary and/or secondary care, and how FIT should be incorporated into diagnostic pathways. Controversy also exists as to the optimum cut-off used for referral for colonoscopy. A single sample of faeces may be sufficient. Reporting of results requires consideration. FIT provide a good rule in test for colorectal cancer and a good rule out test for significant bowel disease, but robust safety-netting is required for patients with negative results and ongoing symptoms. Risk scoring models have been developed, but their value is unclear as yet. Further evaluation of these topics is required to inform good practice.

Symptom or faecal immunochemical test based referral criteria for colorectal cancer detection in symptomatic patients: a diagnostic tests study

BACKGROUND

Symptom based referral criteria for colorectal cancer (CRC) detection are the cornerstone of the strategy to improve prognosis in CRC. In 2017, the National Institute for Health and Care Excellence (NICE) updated their referral criteria (2017 NG12). Recently, several studies have evaluated the faecal haemoglobin (f-Hb) concentration in this setting. The aim of this study is to evaluate the diagnostic accuracy of the 2017 NG12 referral criteria and to compare them with the CG27 referral criteria, the f-Hb concentration and two f-Hb based prediction model: COLONPREDICT and FAST Score.

METHODS

This is a post-hoc diagnostic test study performed within the COLONPREDICT study database (1572 patients, CRC prevalence 13.6%). We assessed symptoms, the 2017 NG12 and CG27 referral criteria and determined the f-Hb before performing a colonoscopy. We compared the discriminatory ability using the area under the curve (AUC) and the sensitivity and specificity at pre-stablished thresholds with the McNemar's test.

RESULTS

The 2017 NG12 referral criteria discriminatory ability (AUC 0.53; 95% confidence interval- CI 0.49-0.57) was inferior to the CG27 version (AUC 0.59; 95% CI 0.55-0.63; p = 0.01), the f-Hb concentration (AUC 0.86; 95% CI 0.84-0-89; p < 0.001), the COLONPREDICT Score (AUC 0.92; 95% CI 0.91-0.94; p < 0.001) or the FAST Score (AUC 0.87; 95% CI 0.85-0.89; p < 0.001). The number of patients meeting each criteria were as follows: 2017 NG12 and CG27 = 94.1% and 52.2%; f-Hb ≥20 and ≥ 10 μg/g faeces = 38.6 and 44.3%; COLONPREDICT Score ≥ 5.6 and ≥ 3.2 = 29.4 and 63.2% and FAST Score ≥ 4.50 and ≥ 2.12 = 37.1 and 87.0%. The 2017 NG12 criteria were more sensitive (100%) than the CG27 criteria (68.2%), the f-Hb (≥20 μg/g) (91.2%), the f-Hb (≥10 μg/g) (93.5%), the COLONPREDICT Score (≥5.6) (90.1%) and the FAST Score (≥4.50) (89.8%) (p ≤ 0.001) and equivalent to the COLONPREDICT Score (≥3.5) (99.5%) or the FAST Score (≥2.12) (100.0%) (p = 1). However, their specificity (6.8%) was significantly lower than any of the evaluated criteria (50.3%, 69.6%, 63.4%, 78.7%, 45.8%, 71.3%, 13.9%; p < 0.001).

CONCLUSION

Referral criteria based on f-Hb measurement, either as a single test or within prediction models, are more accurate than symptom-based referral criteria for CRC detection in symptomatic patients.

Setting up a service for a faecal immunochemical test for haemoglobin (FIT): a review of considerations, challenges and constraints

Quantitative faecal immunochemical tests for haemoglobin (FIT) have now been advocated by the National Institute for Care and Health Excellence (NICE: DG30) to assist in the triage of patients presenting with symptoms that suggest a low risk of colorectal (bowel) cancer. The evidence is that FIT provides a good rule out test for significant bowel disease. However, a small number of cases will be missed, and robust safety-netting procedures are required to follow up some FIT-negative patients. A range of diagnostic pathways are possible, and there is no best approach at present. Introduction of FIT requires careful consideration of the logistics of supply of devices and information to requesting sites and of transport to the laboratory. A number of FIT analytical systems are available. Three are documented as appropriate for use in assessment of patients with symptoms. However, preanalytical, analytical and postanalytical challenges remain. The methods have different specimen collection devices. The methods use polyclonal antibodies and there is no primary reference material or method to which FIT methods are standardised. Third-party internal quality control is lacking, and external quality assessment schemes have many difficulties in providing appropriate materials. Reporting of results should be done using µg Hb/g faeces units and with knowledge of the limit of detection and limit of quantitation of the analytical system used. FIT can be used successfully in an agreed diagnostic pathway, along with other clinical and laboratory information: this requires a multidisciplinary approach, providing opportunities for professionals in laboratory medicine involvement.

Guidelines for the investigation of chronic diarrhoea in adults: British Society of Gastroenterology, 3rd edition

Chronic diarrhoea is a common problem, hence clear guidance on investigations is required. This is an updated guideline from 2003 for the investigations of chronic diarrhoea commissioned by the Clinical Services and Standards Committee of the British Society of Gastroenterology (BSG). This document has undergone significant revision in content through input by 13 members of the Guideline Development Group (GDG) representing various institutions. The GRADE system was used to appraise the quality of evidence and grading of recommendations.

Faecal immunochemical tests (FIT) in the assessment of patients presenting with lower bowel symptoms: Concepts and challenges

Colonoscopy is a relatively scarce resource in many countries, including Scotland, and a simple investigation which would aid general practitioners in particular in decision-making as to which patients presenting with lower bowel symptoms warranted referral would be of much help. Faecal immunochemical tests for haemoglobin (FIT) have many advantageous characteristics and are now proven to be of considerable value in the timely assessment of patients with symptoms of lower bowel disease. Quantitative FIT provide numerical estimates of faecal haemoglobin concentration (f-Hb) and, at low f-Hb cut-off, FIT have high sensitivity for colorectal cancer (CRC) and could be used as a rule-in test to stimulate rapid referral, especially when symptoms are suggestive of serious bowel disease. Perhaps more importantly, a low f-Hb gives considerable reassurance that significant bowel disease (CRC + higher-risk adenoma + inflammatory bowel disease) is absent and further investigation may not be warranted: however, no test is perfect, so some cases will remain undetected using FIT alone and robust safety netting is required, possibly including watching and waiting, referral to clinics in secondary care, or a repeat FIT. Moreover, the FIT results should not be taken in isolation, but clinical impressions and the results of other investigations, probably including the full blood count, should be considered. Challenges still exist, however, and harmonisation of aspects of the available FIT analytical systems is required. Moreover, a number of seemingly valid clinical concerns remain and these require resolution through further research and reporting of studies done in real clinical practice.