Does Genetic Susceptibility for Bleeding Affect Quantitative Faecal Immunochemical Test (qFIT) Results?
Does Genetic Susceptibility for Bleeding Affect Quantitative Faecal Immunochemical Test (qFIT) Results? - a Feasibility Study
Quantitative faecal immunochemical testing (qFIT) is used to test for blood within faeces that cannot always be visible. The presence of blood in the stool has been shown to be a finding where there may be a problem within the large bowel. The test is able to give a numeric value to the blood in the stool and based on this result, further investigations can be planned, or if normal reassurance given.
The test is not perfect and minor bowel problems such as haemorrhoids (piles) can give a raised result. However, we have also seen raised results in people who when investigated have a completely normal large bowel. A small degree of 'physiological' non-visible bleeding is likely a normal part of life and for the majority this does not lead to a raised qFIT result.
It may be the case in people who have a raised qFIT but then go on to have a completely normal colonoscopy (telescope investigation of the large bowel) that there is a genetic predisposition that increases the amount of normal 'physiological blood' that they produce. This leads to the test being falsely positive and the person undergoing an unnecessary investigation.
This study aims to use saliva to test for known genetic markers that effect blood clotting and can increase how much someone bleeds. By comparing the occurrence of these genetic markers in people with a raised qFIT and normal colonoscopy to those with a normal qFIT and normal colonoscopy, we can test this theory. Should this be the case it will help explain why the test can be raised in normal large bowel and could lead to different levels of positivity being used for different people.
Study Overview
Status
Conditions
Intervention / Treatment
Detailed Description
Quantitative faecal immunochemical testing (qFIT) measures the presence of haemoglobin within faeces. It is an immunoassay based method, measuring the globin portion of human haemoglobin or its early degradation products. Diet does not impact the result and because globin is broken down by gastric enzymes, it is more specific to lower gastrointestinal (GI) bleeding than previously used guaiac based occult blood tests. qFIT is the test currently used by the Scottish and English National Bowel Screening Programmes and more recently has been included in NICE guideline DG30, for the investigation of patients with lower gastrointestinal (GI) symptoms who are in a low-risk population.
qFIT is being increasingly used in a manner, unsupported by evidence in some cases, in the investigation of all symptomatic patients to aid decision-making in referral to secondary care and for allocation of endoscopy resources in secondary care. qFIT is not a perfect test to rule out colorectal cancer, a meta-analysis within a symptomatic population estimated the sensitivity for detecting colorectal cancer to be 90% with a specificity of 87%. From our own studies of repeated qFIT (n=3000, unpublished), a large variance is seen between the results. Therefore to improve the utility of qFIT within this group it is likely additional factors will also need to be considered, such as an individual's genetic susceptibility for bleeding.
There are well known genetic variants resulting in coagulopathy conditions such as haemophilia and von Willebrand disease. However, it has been shown that the levels of coagulation associated proteins vary within the population and this variation is linked with genetics. Multiple genes have been implicated in coagulation, and within them hundreds of singe nucleotide polymorphisms (SNPs). Reduced levels of circulating coagulation proteins may explain false positive cases seen with qFIT.
This study aims to add further knowledge to the utility of qFIT when investigating patients with lower gastrointestinal symptoms. There are a significant proportion of people who have a raised qFIT and normal colonoscopy (gold standard investigation). In our data approximately 10% of those with a completely normal colonoscopy had a raised qFIT defined as >10 µg Hb/g. It is possible that these patients have a genetic susceptibility to bleeding and therefore have higher levels of faecal haemoglobin without any pathology. There are known genetic markers for bleeding tendency. By comparing these genetic traits in patients with a normal colonoscopy but a qFIT >10 µg Hb/g against <10 µg Hb/g the potential effects of these genes on qFIT results may be evaluated.
Study Type
Contacts and Locations
Study Locations
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Edinburgh, United Kingdom
- NHS Lothian
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Participation Criteria
Eligibility Criteria
Ages Eligible for Study
Accepts Healthy Volunteers
Sampling Method
Study Population
Description
Inclusion Criteria:
- Patients who were symptomatic at the time of referral
- Returned at least one qFIT sample
- Underwent a complete colonoscopy, which did not identify any pathology
- Willing to provide a saliva sample for genetic analysis
- Are able to consent to the study
Exclusion Criteria:
- Age < 18
- Previous colorectal cancer
- Ongoing colonic polyp surveillance
- Known inflammatory bowel disease
- Taking anticoagulant medication (Aspirin, clopidogrel, warfarin or NOAC)
- History of liver disease or known bleeding disorder
- Incomplete colonoscopy
- Unable to consent to the study
Study Plan
How is the study designed?
Design Details
Cohorts and Interventions
Group / Cohort |
Intervention / Treatment |
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Normal Colonoscopy and Normal qFIT
Normal colonoscopy and qFIT <10 micrograms haemoglobin
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SNP arrays for known bleeding SNPs to compare genetics of patients with normal colonoscopy and normal qFIT vs raised qFIT
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Normal Colonoscopy and Raised qFIT
Normal colonoscopy and qFIT >=10 micrograms haemoglobin
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SNP arrays for known bleeding SNPs to compare genetics of patients with normal colonoscopy and normal qFIT vs raised qFIT
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What is the study measuring?
Primary Outcome Measures
Outcome Measure |
Measure Description |
Time Frame |
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Accumulation of SNPs related to bleeding in patients with a normal colonoscopy and a raised qFIT compared to those with a qFIT less than 10 µg Hb/g.
Time Frame: Saliva sample will be collected within 1 month of recruitment. Assessment will require all results from the study participants before analysis can be performed. Aimed to be within 6 months of sample collection completion
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SNP array performed on dna from saliva samples
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Saliva sample will be collected within 1 month of recruitment. Assessment will require all results from the study participants before analysis can be performed. Aimed to be within 6 months of sample collection completion
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Collaborators and Investigators
Sponsor
Collaborators
Investigators
- Principal Investigator: Farhat Din, FRCSed, University of Edinburgh
Study record dates
Study Major Dates
Study Start (Estimated)
Primary Completion (Estimated)
Study Completion (Estimated)
Study Registration Dates
First Submitted
First Submitted That Met QC Criteria
First Posted (Actual)
Study Record Updates
Last Update Posted (Estimated)
Last Update Submitted That Met QC Criteria
Last Verified
More Information
Terms related to this study
Additional Relevant MeSH Terms
Other Study ID Numbers
- AC21145
Plan for Individual participant data (IPD)
Plan to Share Individual Participant Data (IPD)?
IPD Plan Description
Drug and device information, study documents
Studies a U.S. FDA-regulated drug product
Studies a U.S. FDA-regulated device product
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