Performance of the faecal immunochemical test for the detection of colorectal neoplasms and the role of proton pump inhibitors in their diagnostic accuracy

Faecal immunochemical testing (FIT) in primary care: a follow-up service evaluation

AIM

Colorectal cancer (CRC) is the fourth most common cancer in the UK. Following National Institute for Health and Care Excellence guidance for faecal immunochemical testing (FIT), we introduced a service for the measurement of faecal haemoglobin (f-Hb) in symptomatic patients. Previously, we evaluated the first 6 months of the service in three local boroughs, here we re-examine the use of FIT, over a similar 6 months in the two successive years.

METHODS

Patients who had FIT requested in April-September 2020 and 2021 were studied. Results were obtained from the laboratory information systems and matched with the clinical outcomes of those referred via the urgent lower gastrointestinal cancer pathway. Patient demographics, reason for referral, clinical outcome and diagnostic test performance are reported.

RESULTS

In 2020, 4042 samples were analysed and 57 CRC detected. In 2021, 10 508 samples were analysed and 65 CRC detected. Six (4.9%) patients with CRC had f-Hb <10 µg/g, of whom three were anaemic. In 2020, 27.7% of samples were from patients under 50 years; and in 2021, 32.8%. Sensitivity, specificity, positive predictive value and negative predictive value of f-Hb at ≥10 µg/g for CRC were 92.9%, 46.6%, 6.4% and 99.4% in 2020 and 96.9%, 29.9%, 3.2% and 99.8% in 2021.

CONCLUSIONS

As currently used in primary care in North East London, specificity of FIT at a cut-off of 10 µg/g is much lower than in published studies and the impact of this on colorectal services needs to be considered.

Effect of aspirin, warfarin, and proton-pump inhibitors on performance of fecal immunochemical test in colorectal cancer screening: a systematic review and meta-analysis

This study aims to investigate the impact of antithrombotic agents and proton-pump inhibitors (PPIs) on fecal immunochemical test (FIT). PubMed, EMBASE, Web of Science, Cochrane Central, and Google Scholar were searched from inception until September 3, 2023. Studies comparing the diagnostic performance of FIT between medicine users and non-users in average-risk colorectal cancer screening populations were included. Pooled sensitivity, specificity, and positive predictive values (PPVs) for advanced neoplasia (AN) of FIT were compared by reporting pooled odds ratios (ORs) with 95% confidence intervals (CIs) using a random-effects model. Twenty-two studies enrolling 5,572,367 individuals were included. For aspirin, pooled sensitivity and specificity for AN were 57.2% and 88.4% in users versus 60.2% and 93.2% in non-users; while pooled ORs were 1.49 (95% CI 0.89-2.48, P = 0.13) and 0.72 (95% CI 0.62-0.83, P < 0.001), respectively. In subgroup analysis, there was no difference in sensitivity and specificity between the two groups at the cutoff of 20 μg Hb/g (P = 0.57 and 0.29, respectively) but a significantly lower specificity in users compared with non-users at lower cutoffs (P < 0.001). Moreover, a significantly lower PPVAN in users compared with non-users was observed after matching age and sex confounders (P = 0.001). Warfarin had no significant influence on PPVAN of FIT (P = 0.43). PPIs were associated with a significantly lower PPVAN in users (P < 0.001). Aspirin use was associated with lower specificity and PPV of FIT. Aspirin discontinuation before FIT to reduce false-positive results should be interpreted with caution given concerns about cardiovascular events. Increasing cutoff values of FIT in aspirin users may be another possible approach. Additionally, warfarin withdrawal before FIT is unnecessary but PPIs withdrawal before FIT is recommended to reduce false-positive results.

A Multi-Centre Study to Risk Stratify Colorectal Polyp Surveillance Patients Utilising Volatile Organic Compounds and Faecal Immunochemical Test

Simple Summary

A total of 15% of the annual colonoscopies are undertaken for polyp surveillance, and this causes strain on already stretched endoscopy services in the U.K. Hence, there is an urgent need to triage and prioritise patients with high-risk findings. The performance of the faecal immunochemical test is not adequate to be used within polyp surveillance. In light of this, we investigated the usefulness of urinary volatile organic compounds for the detection of high-risk findings. We confirmed that urinary volatile organic compounds can be used to triage patients with high-risk findings. It can be used alone or in combination with faecal immunochemical tests.

Abstract

(1) Background: The service capacity for colonoscopy remains constrained, and while efforts are being made to recover elective services, polyp surveillance remains a challenge. (2) Methods: This is a multi-centre study recruiting patients already on polyp surveillance. Stool and urine samples were collected for the faecal immunochemical test (FIT) and volatile organic compounds (VOC) analysis, and all participants then underwent surveillance colonoscopy. (3) Results: The sensitivity and specificity of VOC for the detection of a high-risk finding ((≥2 premalignant polyps including ≥1 advanced polyp or ≥5 premalignant polyps) were 0.94 (95% CI, 0.88 to 0.98) and 0.69 (95% CI, 0.64 to 0.75) respectively. For FIT, the sensitivity was (≥10 µg of haemoglobin (Hb) / g faeces) 0.54 (95% CI, 0.43 to 0.65) and the specificity was 0.79 (95% CI, 0.73 to 0.84). The probability reduction for having a high-risk finding following both negative VOC and FIT will be 24% if both tests are applied sequentially. (4) Conclusion: The diagnostic performance of VOC is superior to FIT for the detection of a high-risk finding. The performance further improves when VOC is applied together with FIT sequentially (VOC first and then FIT). VOC alone or the combination of VOC and FIT can be used as a triage tool for patients awaiting colonoscopy within a polyp surveillance population, especially in resource-constrained healthcare systems.

Faecal immunochemical testing (FIT) in patients with signs or symptoms of suspected colorectal cancer (CRC): a joint guideline from the Association of Coloproctology of Great Britain and Ireland (ACPGBI) and the British Society of Gastroenterology (BSG)

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.

Faecal Haemoglobin Estimated by Faecal Immunochemical Tests-An Indicator of Systemic Inflammation with Real Clinical Potential

Multimorbidity is the major cause of ill-health and premature death in developed countries. The ability to identify individuals at risk of developing chronic disease, particularly multimorbidity, reliably, and simply, and to identify undiagnosed disorders, is vital to reducing the global burden of disease. This narrative review, the first of recent studies, demonstrates that raised faecal haemoglobin concentration (f-Hb) is associated with increased all-cause and cause-specific mortality and with longer-term conditions including diabetes, hypertension, cardiovascular disease, and psoriasis, and with probable intake of particulate matter. We and others have hypothesized that elevated f-Hb (measured using a faecal immunochemical test) has considerable potential to identify individuals at risk of, or who already have, early stage, undiagnosed chronic disease. If f-Hb does prove to be an effective biomarker for chronic disease and multimorbidity, individuals with detectable f-Hb, but without an obvious source of gastrointestinal blood loss, could benefit from further assessment and early intervention. To test this hypothesis rigorously, longitudinal data-linkage methodology is required linking colorectal cancer screening data, and data on patients presenting with lower gastrointestinal symptoms, with routinely collected health information.

Consistent Major Differences in Sex- and Age-Specific Diagnostic Performance among Nine Faecal Immunochemical Tests Used for Colorectal Cancer Screening

Evidence on diagnostic performance of faecal immunochemical tests (FITs) by sex and age is scarce. We aimed to evaluate FIT performance for detection of advanced colorectal neoplasia (AN) by sex and age across nine different FIT brands in a colonoscopy-controlled setting. The faecal samples were obtained from 2042 participants of colonoscopy screening. All eligible cases with AN (n = 216) and 300 randomly selected participants without AN were included. Diagnostic performance for detection of AN was assessed by sex and age (50-64 vs. 65-79 years for each of the nine FITs individually and for all FITs combined. Sensitivity was consistently lower, and specificity was consistently higher for females as compared with males (pooled values at original FIT cutoffs, 25.7% vs. 34.6%, p = 0.12 and 96.2% vs. 90.8%, p < 0.01, respectively). Positive predictive values (PPVs) were similar between both sexes, but negative predictive values (NPVs) were consistently higher for females (pooled values, 91.8% vs. 86.6%, p < 0.01). Sex-specific cutoffs attenuated differences in sensitivities but increased differences in predictive values. According to age, sensitivities and specificities were similar, whereas PPVs were consistently lower and NPVs were consistently higher for the younger participants. A negative FIT is less reliable in ruling out AN among men than among women and among older than among younger participants. Comparisons of measures of diagnostic performance among studies with different sex or age distributions should be interpreted with caution.