Use and abuse of faecal occult blood tests in an acute hospital inpatient setting

Understanding the Utility of Fecal Occult Blood Testing in Hospitalized Patients With Suspected GI Bleeding

Colorectal cancer (CRC) is one of the leading causes of cancer-related mortality worldwide. There have been increasing efforts to reduce its incidence and mortality. Screening plays a crucial role, with various tests such as the fecal occult blood test (FOBT), colonoscopy, and flexible sigmoidoscopy commonly used for investigation. FOBT is a Food and Drug Administration (FDA) approved screening tool commonly used in acute healthcare settings for early detection of CRC. We report a 50-year-old man presenting with shortness of breath, chills, and malaise with findings positive for pneumonia. Laboratory tests revealed anemia as an incidental finding. A subsequent FOBT came back positive, and the patient was admitted for further gastrointestinal testing. Esophagogastroduodenoscopy (EGD) and colonoscopy were performed, but no significant findings were observed. This case report focuses on the overuse of FOBT testing during hospital admission, despite its limited impact on patient care in acute settings. Key takeaways include being aware of the potential for false positive and false negative results from a FOBT. Using the test carefully can help reduce both direct and indirect healthcare costs for hospitalized patients, as well as minimize the use of hospital resources. The test should primarily be used for CRC screening in the outpatient setting.

Evaluation of fecal occult blood testing for rapid diagnosis of invasive diarrhea in young children

Antimicrobials are only indicated in acute childhood diarrhea if it is invasive or persistent. Rapid screening for invasive diarrhea can therefore inform treatment decisions but pathogen identification by culture is slow, expensive and cumbersome. This study aimed to assess the diagnostic utility of stool microscopy and immunochromatographic fecal occult blood test (FOBT) kits for identifying invasive or potentially invasive diarrhea in Ibadan, Nigeria. Fecal specimens from 46 children under 5 years old with diarrhea, collected as part of ongoing case-control studies, were subjected to stool microscopy for erythrocytes and leucocytes, and FOBT using the innovator's product and four locally procurable generic immunochromatographic kits, each according to manufacturers' instructions. Stool specimens were cultured for enteric bacterial pathogens using standard procedures. Presumptive pathogen isolates were identified biochemically and by PCR, and then confirmed by whole genome sequencing. Shigella, enteroinvasive Escherichia coli and Yersinia, pathogens that invariably cause invasive diarrhea, were detected in five of 46 specimens. Occult blood detection by microscopy was 55.6% sensitive and 78.4% specific, while the innovator's FOBT product was respectively 62.5% and 81.6% sensitive and specific compared to strict invasive pathogen recovery. Microscopy and FOBT testing were less sensitive in identifying specimens that contained pathogens that do not always elicit invasive diarrhea. Generic FOBT tests compared well with the innovator's product. Microscopy and FOBT testing have some value for delineating likely invasive diarrheas. They could inform treatment and serve as early warning indicators for dysentery outbreaks in resource limited settings. Inexpensive, generic FOBT kits that are locally procurable in Nigeria performed as well as the innovator's product.

Outcomes of Hospitalized Patients With Fecal Occult Positive Stool Prior to Cardiac Catheterization in Acute Coronary Syndrome (ACS)

Introduction Cardiac catheterization is an essential component of patient care in Acute Coronary Syndrome (ACS). Fecal occult blood testing (FOBT) has been used in the inpatient setting to evaluate the risk of bleeding with dual anti-platelet therapy prior to cardiac catheterization although no guidelines exist for this indication and FOBT testing in the inpatient setting is not recommended for evaluation of GI blood loss. We sought to assess the outcomes of patients with fecal occult positive stool prior to cardiac catheterization compared to those that did not undergo FOBT during admission for non-ST-elevation myocardial infarction (NSTEMI). Methods We identified patients between 18 and 90 years old with admission for NSTEMI in the Trinetx Research Network from January 1, 2019 to December 31, 2020. Patients were then divided into those who had an FOBT prior to cardiac catheterization and those that did not have an FOBT. We compared all-cause mortality, bleeding, troponin levels, and length of stay between propensity-matched (PSM) pairs of patients. Results We identified 46,349 that met inclusion criteria, of which 1,728 had an FOBT (3.7%) and 44,621 (96.3%) had no FOBT prior to cardiac catheterization. Patients in the FOBT group were older and had a higher prevalence of hypertension, coronary artery disease, heart failure, diabetes, chronic obstructive pulmonary disease, and higher BMI. Two well-matched groups of n=1,728/1,728 were used for comparing outcomes. The FOBT group had similar 30-day mortality (4.45% vs 4.01, P=0.56) as well as similar bleeding events (0.98% vs 0.69%, P=0.35). Troponin levels in the FOBT group were on average lower (0.41 vs 0.95, P=0.04). The FOBT groups also had a similar average length of stay of (14.1 days vs 14.2 days, P=0.42). 233 patients who received FOBT underwent endoscopic evaluation with either upper endoscopy or colonoscopy (13.5%), and there was no significant difference in 30-day mortality (6.86% vs 4.7%, P=0.321). Among patients who underwent endoscopy, 72 had some form of endoscopic intervention (30.9%). There was no difference in 30-day mortality between patients undergoing endoscopy with intervention and without intervention (14.49%/14.49%) P=1.00. Readmission was similar between patients undergoing endoscopy with and without intervention. Conclusions In a large multi-center national database, we observed similar outcomes in patients who were admitted with NSTEMI and had FOBT and those not receiving FOBT in terms of all-cause mortality and bleeding events. In patients with positive FOBT, endoscopy with and without intervention we observed no significant difference in 30-day mortality. We conclude that there is no compelling evidence for FOBT testing in patients with NSTEMI.

Anemia as a Problem: GEH Approach

BACKGROUND

Anemia is present in almost 5% of adults worldwide and accompanies clinical findings in many diseases. Diseases of the gastrointestinal (GI) tract and liver are a common cause of anemia, so patients with anemia are often referred to a gastroenterologist.

SUMMARY

Anemia could be caused by various factors such as chronic bleeding, malabsorption, or chronic inflammation. In clinical practice, iron deficiency anemia and the combined forms of anemia due to different pathophysiological mechanisms are most common. Esophagogastroduodenoscopy, colonoscopy, and the small intestine examinations in specific situations play a crucial role in diagnosing anemia. In anemic, GI asymptomatic patients, there are recommendations for bidirectional endoscopy. Although GI malignancies are the most common cause of chronic bleeding, all conditions leading to blood loss, malabsorption, and chronic inflammation should be considered. From a gastroenterologist's perspective, the clinical spectrum of anemia is vast because many different digestive tract diseases lead to bleeding. Key Messages: The gastroenterological approach in solving anemia's problem requires an optimal strategy, consideration of the accompanying clinical signs, and the fastest possible diagnosis. Although patients with symptoms of anemia are often referred to gastroenterologists, the diagnostic approach requires further improvement in everyday clinical practice.

Inpatient usage of faecal calprotectin in a tertiary hospital

INTRODUCTION

Faecal calprotectin is a highly sensitive non-invasive marker of intestinal inflammation that has evidence-based roles in outpatient diagnosis and management of inflammatory bowel disease. This study aimed to examine indications for faecal calprotectin (FCP) in a tertiary inpatient population, and its role in inpatient management and subsequent investigations.

METHODS

An electronic database was used to identify all patients over the age of 18 years who had faecal calprotectin performed during a hospital admission over a three year period from March 2016 to the end of March 2019. Electronic records and case notes were reviewed with follow up to March 2020, seeking indication for testing, health care units requesting, and subsequent investigations and treatment resulting from FCP.

RESULTS

Over a three year period 111 faecal calprotectin inpatient results were identified. There were three changes in management based on the FCP result that led to further investigations that did not lead to any clinically significant pathology. There was no observable difference in the number of colonoscopies performed based on FCP level. The numerical FCP value was associated with clinically significant findings on colonoscopy. Negative predictive value of faecal calprotectin level (<= 50 ug/g) for clinically significant finding on colonoscopy was 64%.

CONCLUSION

Non-guideline based hospital inpatient usage of faecal calprotectin rarely changes inpatient management and had no observable difference in the usage of subsequent diagnostic colonoscopy. Regardless the faecal calprotectin level remained a strong predictor of clinically significant pathology on colonoscopy. This article is protected by copyright. All rights reserved.

A Case for Abandoning Inpatient Fecal Occult Blood Testing

Fecal occult blood testing (FOBT) is currently Food and Drug Administration (FDA) approved only for colorectal cancer (CRC) screening. There is now widespread off-label use of FOBT in the hospital setting as a diagnostic test. Here we present a brief case and a more detailed review of the literature arguing against inpatient FOBT. Inpatient use of FOBT is problematic for several reasons including failure to account for false positives or negatives, delays in appropriate consultations or endoscopy, increased costs, increase length of stays, unnecessary procedures, and test results that do not change management. Inappropriate use of FOBT can lead to both overuse and underuse of endoscopy. Many retrospective audit studies and more recently a meta-analysis have shown that FOBTs have poor test performance and are unable rule out the need for endoscopy in patients with iron deficiency anemia. For these reasons we argue that inpatient FOBT should be abandoned. 

Fecal Occult Blood Test for Evaluation of Symptoms or for Diagnostic Testing

This editorial discusses the role of fecal occult blood test (FOBT) in a diagnostic workup. Utility of FOBT in colorectal cancer screening is well documented in multiple clinical trials, although there continues to be a debate (and ongoing trials) on its merit relative to other screening tests. Over the years, FOBT has seen growth in its application for assessment of symptomatic gastrointestinal disease without clear guidelines on its use in this setting. The work of Lee et al. in this edition of the journal synthesizes evidence on diagnostic utility of FOBT and provides additional rationale to stop using FOBTs for symptoms evaluation or for diagnostic testing.

A Call for a Reconsideration of the Use of Fecal Occult Blood Testing in Emergency Medicine

BACKGROUND

Fecal occult blood testing (FOBT) was developed to detect microscopic bleeding caused by colorectal neoplasms. The role of FOBT in the emergency department (ED) is typically used for 5 different clinical workups: trauma, anemia, syncope, hypotension, and before the administration of systemic anticoagulants or thrombolytics.

OBJECTIVE

We scrutinized the literature to assess the utility of FOBT for its 5 most common applications in the emergent setting.

DISCUSSION

Logic and clinical evidence advocating for FOBT usage in the aforementioned situations are lacking. The test itself requires specific drug and dietary restrictions that are often violated or never met when patients present to the ED with acute pathologies. In addition, the poor sensitivity and specificity of the test in these scenarios dictate that neither a negative nor positive FOBT should change the subsequent clinical workup of patients presenting to the ED.

CONCLUSION

Clinical decision making should seldom be predicated on the results of a FOBT in the ED setting.

Utility of fecal immunochemical test vs guaiac fecal occult blood test for assessment of gastrointestinal bleed in hospitalized patients

BACKGROUND

Guaiac fecal occult blood testing (gFOBT) is often used "off-label" for gastrointestinal (GI) bleeding. Fecal Immunochemical Test (FIT) is increasingly replacing gFOBT in colorectal cancer screening and may play a role in assessment for significant bowel disease. We examined the concordance of FIT with gFOBT (Hemoccult Sensa II) among inpatients and between day 1 and day 3 gFOBT results.

METHODS

FIT was performed alongside gFOBT on all inpatient stool sent for occult blood to the Winnipeg Health Sciences Centre laboratory over 1 y. gFOBT was performed on days 1 and 3 post stool collection, while FIT was performed on day 1 only.

RESULTS

Positivity rates were highest for Day 1 gFOBT (27.7%), and lowest for FIT (18.3%). Concordance between FIT and Days 1 and 3 gFOBT for negative test results (96.4% and 94.1%) was significantly higher than that expected by chance alone (58.7% and 61.3%, P < .001). Similarly, concordance for positive test results (55.8% and 55.6%) was significantly higher as well as for days 1 and 3 gFOBT results.

CONCLUSIONS

We found no benefit in delayed testing for 3 days post collection. FIT provides equivalent results to gFOBT in hospitalized patients.

Use and abuse of fecal occult blood tests: a community hospital experience

Background

The Fecal Occult Blood Test (FOBT) is one of the diagnostic modalities indicated for screening patients for Colorectal Cancer (CRC). Despite being approved only for screening for CRC, numerous studies in the past have illustrated misuse of the FOBT. We examined utilization of the FOBT for patients admitted to a community teaching hospital.

Methods

The study was conducted at Saint Joseph Hospital, Chicago USA. A retrospective review of Electronic Medical Records (EMRs) of patients admitted from January 2016 to December 2017 was performed.

Results

We reviewed the EMRs of 729 patients who received the stool testing for occult blood (FOBT). All tests (100%) were carried out for purposes other than CRC screening. Anemia (38%) was the most common reason documented for carrying out the FOBT. Further, 88% of the tests were ordered on patients who either did not fulfill CRC screening criteria or had other contraindications for testing. Usage of contraindicated medication was the most important factor (58% of patients) that made the candidates ineligible for testing. A total 73 Colonoscopies were ordered for patients who received the test inappropriately with a resulting low yield (0.47%) of CRC diagnosis.

Conclusion

The stool occult blood test continues to be utilized for reasons other than CRC screening. Majority of patients who underwent the test were not suitable candidates due to the presence of contraindications for testing. Unsuitable FOBT testing led to further unnecessary investigations.

Diagnosis of chronic anaemia in gastrointestinal disorders: A guideline by the Italian Association of Hospital Gastroenterologists and Endoscopists (AIGO) and the Italian Society of Paediatric Gastroenterology Hepatology and Nutrition (SIGENP)

Anaemia is a common pathologic condition, present in almost 5% of the adult population. Iron deficiency is the most common cause; other mechanisms can be involved, making anaemia a multi-factorial disorder in most cases. Anaemia being a frequent manifestation in the diseases of the gastrointestinal tract, patients are often referred to gastroenterologists. Furthermore, upper and lower endoscopy and enteroscopy are pivotal to the diagnostic roadmap of anaemia. In spite of its relevance in the daily clinical practice, there is a limited number of gastroenterological guidelines dedicated to the diagnosis of anaemia. For this reason, the Italian Association of Hospital Gastroenterologists and Endoscopists and the Italian Society of Paediatric Gastroenterology, Hepatology and Nutrition commissioned a panel of experts to prepare a specific guideline on anaemia and its diagnostic roadmap in the gastroenterological scenario. The panel also discussed about the potential involvement of gastroenterologists and endoscopists in the management of patients with anaemia, with particular attention to the correct use of investigations. The panel paid particular attention to practical issues with the aim to support gastroenterologists in their clinical practice when dealing with patients with anaemia.

Five common errors to avoid in clinical practice: the Italian Association of Hospital Gastroenterologists and Endoscopists (AIGO) Choosing Wisely Campaign

Modern medicine provides almost infinite diagnostic and therapeutic possibilities if compared to the past. As a result, patients undergo a multiplication of tests and therapies, which in turn may trigger further tests, often based on physicians' attitudes or beliefs, which are not always evidence-based. The Italian Association of Hospital Gastroenterologists and Endoscopists (AIGO) adhered to the Choosing Wisely Campaign to promote an informed, evidence-based approach to gastroenterological problems. The aim of this article is to report the five recommendations of the AIGO Choosing Wisely Campaign, and the process used to develop them. The AIGO members' suggestions regarding inappropriate practices/interventions were collected. One hundred and twenty-one items were identified. Among these, five items were selected and five recommendations were developed. The five recommendations developed were: (1) Do not request a fecal occult blood test outside the colorectal cancer screening programme; (2) Do not repeat surveillance colonoscopy for polyps, after a quality colonoscopy, before the interval suggested by the gastroenterologist on the colonoscopy report, or based on the polyp histology report; (3) Do not repeat esophagogastroduodenoscopy in patients with reflux symptoms, with or without hiatal hernia, in the absence of different symptoms or alarm symptoms; (4) Do not repeat abdominal ultrasound in asymptomatic patients with small hepatic haemangiomas (diameter < 3 cm) once the diagnosis has been established conclusively; (5) Do not routinely prescribe proton pump inhibitors within the context of steroid use or long-term in patients with functional dyspepsia. AIGO adhered to the Choosing Wisely Campaign and developed five recommendations. Further studies are needed to assess the impact of these recommendations in clinical practice with regards to clinical outcome and cost-effectiveness.

Inpatient iron deficiency detection and management: how do general physicians and gastroenterologists perform in a tertiary care hospital?

BACKGROUND

Iron deficiency (ID) is often an indicator of underlying pathology. Early detection and treatment avoids long-term morbidity and allows for prompt iron repletion, avoiding ID anaemia (IDA) and the need for blood transfusion.

AIM

To evaluate the management of ID in two internal medicine units (general medical (GM) and gastroenterology (GE)) in a large metropolitan hospital and compare it to international guidelines.

METHODS

All consecutive inpatient admissions in the GM and GE units were retrospectively reviewed until 40 patients in each service were identified with anaemia and/or microcytic hypochromic blood counts. Patient records and electronic discharge summaries were then reviewed to assess the recognition, investigation and management of these abnormalities.

RESULTS

Overall, only 60% (48/80) of the cases of microcytic hypochromic picture and/or anaemia were recognised. Cases were more likely to be detected under the GE unit, 77.5% (31/40) versus 42% (17/40) in GM (P < 0.002). Of the 31 recognised GE cases, 28 (90%) were investigated further with iron studies and/or endoscopic procedures. ID was confirmed in nearly half (5/11) of those tested; however, only 2 of 5 received iron replacement. Among GM patients, only 11 of the 17 recognised cases (64%) were investigated further. Iron studies were performed in all 11, confirming IDA in 4 (36%), all of whom received intravenous iron. A faecal human haemoglobin test was performed in two GM patients and one GE patient.

CONCLUSION

There remains significant room for improvement in the recognition, investigation and management of ID in hospital practice in Australia.

Utilization of fecal occult blood test in the acute hospital setting and its impact on clinical management and outcomes

Background:

Despite lack of evidence supporting the use of fecal occult blood test (FOBT) in the acute hospital setting, FOBT is commonly used in the inpatient setting for reasons other than colorectal cancer (CRC) screening.

Aims:

To evaluate practice trends in utilizing FOBT on inpatients and its impact on affecting clinical management and outcomes.

Materials and Methods:

A cross-sectional study of consecutive adult patients undergoing FOBT from January 1, 2011 to December 31, 2011 during an acute medical admission at a large urban safety net hospital was performed. Indications for FOBT, and the impact of FOBT results on endoscopic procedures performed and clinical outcomes were assessed. The number of inpatient endoscopic procedures before and after discontinuing inpatient FOBT was also assessed.

Results:

A total of 207 inpatient FOBTs were performed in 2011. The most common reason cited for FOBT was anemia (36%, n = 74) followed by gastrointestinal (GI) bleeding (27%, n = 55). Interestingly, 23% (n = 47) of the patients undergoing inpatient FOBT had overt GI bleeding. As expected, patients with positive FOBT were significantly more likely to undergo endoscopic examinations (P < 0.01). After discontinuing the availability of inpatient FOBT, patients were less likely to undergo endoscopic examinations [odds ratio (OR) 0.80, 95% confidence interval (CI) 0.75-0.85].

Conclusion:

Inappropriate utilization of FOBT in the inpatient setting is common, even when the indication does not support its use. Setting limitations on inpatient FOBT may reduce the inappropriate utilization of inpatient FOBT. Quality improvement initiatives are needed to educate clinicians on the appropriate use of FOBT, which is primarily for average risk CRC screening.

Use of fecal occult blood testing in hospitalized patients: results of an audit

BACKGROUND

The fecal occult blood test (FOBT), widely used as a colorectal cancer screening tool, continues to be used in hospitalized patients. However, the utility of this test for hospitalized patients is unclear.

OBJECTIVE

To assess FOBT use in a large urban regional health authority.

METHODS

Reports of all FOBTs performed between April 1, 2011 and March 30, 2012 from two academic and four community hospitals in Winnipeg (Manitoba) were extracted. Of 650 hospitalizations with a positive FOBT result and 1254 with a negative FOBT result, random samples of 230 and 97 charts, respectively, were reviewed. Information including demographics, admission diagnos(es), indication(s) for ordering the FOBT and clinical management was extracted.

RESULTS

Thirty-four percent (650 of 1904) of hospitalizations with an FOBT had a positive FOBT result. Family medicine physicians ordered approximately one-half of the reviewed FOBTs. The most common indication for ordering an FOBT was anemia. Of those with a positive FOBT, 66% did not undergo further gastrointestinal investigations. Of those with a positive FOBT and overt gastrointestinal bleeding and⁄or melena who underwent endoscopy, 60% had their endoscopy performed before the FOBT result being reported while 38% underwent their endoscopy ≥3 days after the stool sample was collected. There were minimal differences in clinical practices between academic and community hospitals.

CONCLUSIONS

The present study suggests that FOBT results in hospitalized patients may have little beneficial impact on clinical management. Hospital laboratories may be better served in directing resources to other tests.

Use of fecal occult blood test in hospitalized patients: survey of physicians practicing in a large central Canadian health region and Canadian gastroenterologists

BACKGROUND

Although the fecal occult blood test (FOBT) was developed for colorectal cancer screening in the outpatient setting, it continues to be used among hospitalized patients. No previous study has evaluated the knowledge, beliefs and attitudes of practicing physicians on the use of FOBT among hospitalized patients and compared practices among physicians with different medical specialty training.

OBJECTIVE

To survey physicians in the Winnipeg Regional Health Authority (WRHA) and Canadian gastroenterologists (GIs) on the use of FOBT in hospitals.

METHODS

A survey was distributed by e-mail to internists (n=198), emergency medicine (EM) physicians (n=118), general surgeons (n=47) and family medicine (FM) physicians with admitting privileges (n=29) in the WRHA. Canadian GIs were surveyed through the membership database of the Canadian Association of Gastroenterology (CAG) (n=449). The survey included items regarding demographics of the respondents and their current use of FOBT in hospitals.

RESULTS

Response rates ranged from 18% among CAG members to 69% among FM physicians in the WRHA. General internal medicine, general surgeon and GI respondents were less likely to order a FOBT and less likely to believe that an FOBT was useful in assessing emergency room or hospitalized patients when compared with FM and EM respondents (P<0.001). The most common indications for ordering a FOBT were black stools and anemia with and without iron deficiency. Two-thirds of EM physicians preferred point-of-care testing rather than laboratory reporting of FOBT.

CONCLUSIONS

The present survey suggests that FOBTs are commonly used in hospitals by EM and FM physicians for indications such as anemia and black stools.

Fecal occult blood testing as a diagnostic test in symptomatic patients is not useful: a retrospective chart review

BACKGROUND

The fecal occult blood test (FOBT) is a screening tool designed for the early detection of colorectal cancer in primary care. Although not validated for use in hospitalized patients, it is often used by hospital physicians for reasons other than asymptomatic screening.

OBJECTIVE

To profile the in-hospital use of the FOBT and assess its impact on patient care.

METHODS

Patient charts were retrospectively reviewed for all FOBTs conducted over a three-month period in 2011 by the central laboratory supporting the three acute care campuses of Hamilton Health Sciences (Hamilton, Ontario).

RESULTS

A total of 229 patients underwent 351 tests; 52% were female and the mean age was 49 years (range one to 104 years). A total of 80 (34.9%) patients had at least one positive test. The most common indications for testing were anemia (51.0%) and overt gastrointestinal bleeding (19.2%). Only one patient had testing performed for asymptomatic colorectal cancer screening. In only 20 (8.7%) cases medications were modified before testing and diet was modified in only 21 (9.2%) cases. Most patients (85.2%) were taking one or more medications that could result in a false-positive result. Only 18 (7.9%) patients had a digital rectal examinations documented, of which seven were positive. All patients with a positive digital rectal examination underwent endoscopic procedures that revealed a source of bleeding. Among 44 patients with overt gastrointestinal bleeding, 12 (27.3%) had endoscopic investigations delayed to await results of the FOBT. Four patients were referred despite a negative FOBT due to a high degree of suspicion of gastrointestinal bleeding.

CONCLUSIONS

The FOBT is often used inappropriately in the hospital setting. Confounding factors, such as diet and medication use, which may lead to false positives, are often ignored. Use of the FOBT in-hospital may lead to inappropriate management of patients, increased length of stay and increased direct medical costs. Use of the FOBT should be limited to validated indications only.

Inappropriate use of the faecal occult blood test outside of the National Health Service colorectal cancer screening programme

OBJECTIVE

The faecal occult blood test (FOBT) is the screening test validated for use in the National Health Service (NHS) Bowel Cancer Screening Programme (BCSP) after trials demonstrated a 16% reduction in colorectal cancer-specific mortality. FOBT is not validated for use outside the BCSP. The aim was to investigate the number of FOBTs performed outside of the NHS BCSP at a single centre.

METHODS

All FOBTs performed over 1 year were identified. Basic patient demographics, requesting physician and FOBT results were obtained. Referrals and outcomes of the investigation following the FOBT were collected.

RESULTS

A total of 758 FOBTs were requested in 701 patients (352 female; median age 69; range 16-99). The majority (91%) were requested by general practitioners. A total of 515 out of 758 tests (68%) were performed in patients outside the NHS BCSP age range. Thirty-seven out of 86 positive FOBTs were investigated, diagnosing four rectal cancers and two polyps. Forty-nine out of 87 patients with a positive FOBT were not investigated further by the requesting physician or the test repeated. Of the remaining 672 FOBTs, 615 were negative and 57 were either incomplete or unsuitable for analysis. A total of 111 patients (18%) were referred to hospital and 105 of these had FOBT performed as part of the referral process.

CONCLUSION

Our study demonstrates significant misuse of the FOBT outside the NHS BCSP. Inappropriate use leads to false positives and exposes patients to unnecessary risk. False negatives provide reassurance to patients who may have symptoms that should be investigated. The FOBT should not be available to physicians in either primary or secondary care and be restricted to NHS BCSP.

A future for faecal haemoglobin measurements in the medical laboratory

Guaiac-based faecal occult blood tests (gFOBT) are still used in asymptomatic population bowel screening programmes but are being replaced by faecal immunochemical tests (FIT) for haemoglobin. gFOBT have many well-documented disadvantages and there is little evidence for their use in assessment of the symptomatic. Many laboratories have eliminated gFOBT from their approved repertoires by invoking the authoritative published guidelines. Data continue to accumulate that gFOBT are obsolete. FIT are available in two formats, qualitative and quantitative, the latter having advantages that the faecal haemoglobin concentrations are measured and cut-off concentrations that stimulate further investigation can be user-defined. There is growing evidence that FIT would be useful in a spectrum of clinical settings in addition to screening. All laboratories should have FIT in their existing repertoire. For some uses, qualitative FIT would be adequate. However, much evidence has accumulated that measurements of faecal haemoglobin concentrations are beneficial for the assessment of both disease severity and the future risk of colorectal neoplasia. Interpretation requires appreciation that faecal haemoglobin concentrations are higher in men than women and rise with age. It might well be that risk scoring systems that take gender and age into account, possibly with other factors including symptoms, will benefit individuals. Laboratories should consider how quantitative faecal haemoglobin measurements could be brought into routine practice and included in their forward planning. External quality assessment is needed. Specialists in laboratory medicine are urged to play a significant role in the research and development still required to make this a truly mature investigation.