Immunochemical fecal occult blood test is inadequate for screening test of stomach cancer

Introducing the Sanguis-Filum for Detection of Gastric Mucosal Lesions Prior to Endoscopy: A Study Protocol

Early diagnosis of gastric cancer (GC) is compromised by a lack of specific signs to enable identification of affected individuals. We designed the Sanguis-filum (S-filum) as a simple bedside tool that could be used to detect the presence of gastric mucosal lesions prior to endoscopy. We previously published evidence that at a sensitivity of 91%, the presence of free blood in the stomach was associated with mucosal lesions. The S-filum is made of an inert but absorbent string coiled up in a gelatin capsule (Capsuline, FL, USA), which can be swallowed and the string retrieved to test for free blood. Preliminary testing of the S-filum was successfully conducted on healthy volunteers. We now intend to test it on actual patients, comparing the results to oesophagogastroduodenoscopy (OGD) findings. This will enable us to determine the diagnostic accuracy of the S-filum at detecting GC and other mucosal lesions. The S-filum as a bedside tool has the potential to assist healthcare providers to identify individuals likely to have early gastric mucosal lesions and requiring OGD examination. The S-filum could, in the long run, facilitate population-wide screening for early GC prior to endoscopy.

Ultrasensitive Graphene-Based Nanobiosensor for Rapid Detection of Hemoglobin in Undiluted Biofluids

Detection of hemoglobin (Hb), a critical part of the biological system that is responsible for oxygen transportation, is of great significance on clinical diagnosis of various diseases. Particularly, time-efficient Hb detection under nanomole levels has drawn much attention in recent years. Herein, we present a graphene field effect transistor (GFET)-based aptameric nanobiosensor for rapid detection of Hb in undiluted biofluids including serum and urine and for the first time use polyethylenimine (PEI), a kind of comparatively low-cost polymer consisting of numerous amino groups, which can be directly linked with the anchor molecule without any pretreatment as the graphene surface passivation agent. Experimental results indicate the PEI-modified graphene aptameric nanobiosensor can respond to the Hb concentration change in a few minutes (6-8 min) with estimated detection limits of 10.6 fM in 1× PBS, 14.2 fM in undiluted serum, and 11.9 fM in undiluted urine, respectively. Further, considering the potential use of our sensor for implantable and wearable applications, we also examine the sensing performance of the sensor fabricated on an ultrathin flexible polyethylene terephthalate (PET) substrate. The Hb detection results are almost invariable even after 100 cycles of cyclic extension by 120% or 100 cycles of bending with a radius of 1 mm. Hence, our sensor holds great potential for accurate monitoring of nanomole levels of Hb in clinical applications.

Colorectal cancer screening programme: is the French faecal immunological test (FIT) threshold optimal?

BACKGROUND

In France, the colorectal cancer organised screening programme uses the faecal immunological test. A positive test ⩾30 μg Hb/g of stool leads to a colonoscopy for identification of potential colorectal lesions. Cut-off values vary from 20 to 47 μg Hb/g of stool in Western countries. We herein question this threshold's relevance in a French population and perform a retrospective observational study using the Parisian database between 1 April 2015 and 31 December 2018.

METHODS

Rates of participation, numbers of positive faecal immunological test (FIT), detection rates and positive predictive values for advanced adenomas and/or colorectal cancer were determined. Mean positivity values for colorectal lesions were calculated.

RESULTS

In our population, there were 4.1% positive tests and 67.6% colonoscopy results available with final reports. Positive predictive value for advanced adenomas and colorectal cancer were 30% [95% confidence interval (CI) 29.8-30.3] and 7.4% (95% CI 7.35-7.52), respectively. The mean positivity value for all positive tests in our population was 101.7 µg Hb/g of stool (95% CI 85-118.3). There were 1136 normal colonoscopies (21.4%) with a mean positivity value of 88.6 μg Hb/g of stool. Following a negative test in a first screening campaign, 40.8% of patients in our population performed a second test with a positivity rate of 1.3% and with the encounter of 81 colorectal cancers. The risk of having a positive test during the second screening campaign and finding advanced colorectal lesions significantly increased (all p < 0.001) when comparing negative FIT results ranging between 15 and 29 μg Hb/g of stool to 0 and 14 μg Hb/g of stool from the previous campaign.

CONCLUSION

Using the current positivity threshold, some patients were considered negative with a delay in colorectal cancer diagnosis, suggesting the threshold could be lowered. Also, the mean positivity value for normal colonoscopies was high, raising the question of upper gastrointestinal bleeding.

Systematic upper endoscopy concomitant with colonoscopy performed within the colorectal cancer screening program: Impact on the patients' management

BACKGROUND AND AIMS

The French colorectal cancer screening program is based on a fecal immunochemical test, followed by colonoscopy in case of positivity. The benefit of adding a concomitant upper endoscopy to detect upper digestive lesions (precancerous or others) is still debated. Our aim was to evaluate the frequency of upper digestive lesions detected by upper endoscopy performed concomitantly with colonoscopy following a positive fecal immunochemical test, and their impact on the patients' management (i.e., surveillance, medical treatment, endoscopic or surgical procedure).

METHODS

Data of all the patients who consulted for a positive test between May 2016 and May 2019 in our center, and for whom concomitant upper endoscopy and colonoscopy were performed, were analyzed retrospectively. Patients with significant history of upper gastrointestinal diseases or with current gastrointestinal symptoms were excluded.

RESULTS

One hundred patients were included [median age (min-max): 62 (50-75), men 64%]. Macroscopic and/or microscopic upper digestive lesions were found in 58 of them (58%): Helicobacter pylori infection in 17 patients, gastric precancerous lesions in 9 patients (chronic atrophic gastritis with intestinal metaplasia, n=8, low grade dysplasia, n=1), Barrett's esophagus requiring surveillance in 4 patients, and 1 duodenal adenoma with low-grade dysplasia. In 44 patients (44%), the upper endoscopy findings had an impact on patients' management, with no significant difference between the groups with positive (CRC or advanced adenoma)- or negative (any other lesions or normal) colonoscopy.

CONCLUSION

A systematic upper endoscopy combined with colonoscopy for positive fecal immunochemical test could represent an efficient strategy for upper digestive lesions screening in France. Further studies are necessary to confirm these results and to evaluate cost-effectiveness of this approach.

Positive Fecal Immunochemical Test Results Are Associated with Increased Risks of Esophageal, Stomach, and Small Intestine Cancers

Background: The current guideline does not recommend upper gastrointestinal evaluation for patients with a positive fecal immunochemical test (FIT) and negative colonoscopy results. However, this indication was based on low-quality evidence as data on this issue are very limited. We assessed the risk of proximal cancers (oral or throat, esophageal, stomach, and small intestine cancers) after negative or positive FIT results in the Korean National Cancer Screening Program (NCSP). Methods: Using the NCSP databases, we collected data on participants who underwent FIT between 2009 and 2011. Participants were classified based on FIT results and colorectal cancer (CRC) diagnosed within 1 year after FIT as FIT− (n = 5,551,755), FIT+/CRC− (n = 368,553), and FIT+/CRC+ (n = 12,236). Results: The incidence rates of overall proximal cancers in FIT−, FIT+/CRC−, and FIT+/CRC+ patients within 1, 2, and 3 years after FIT were 0.38%, 0.68%, and 2.26%; 0.57%, 0.93%, and 2.74%; and 0.79%, 1.21%, and 3.15%, respectively. After adjusting confounding variables, the risks of esophageal, stomach, and small intestine cancers as well as overall proximal cancers within 1, 2, and 3 years after FIT were higher in FIT+/CRC− patients than those in FIT− patients. However, the risk of oral or throat cancer did not differ between FIT− and FIT+/CRC− patients. The risks for oral or throat cancer and small intestine cancer were higher in FIT+/CRC+ patients than those in FIT+/CRC− patients. Conclusions: In this population-based study, FIT+/CRC− patients were at higher risk for esophageal, stomach, and small intestine cancers than were FIT− patients, suggesting that positive FIT results were associated with these cancers.

Use of Fecal Occult Blood Testing as a Diagnostic Tool for Clinical Indications: A Systematic Review and Meta-Analysis

INTRODUCTION

Fecal occult blood tests (FOBTs) are validated only for colorectal cancer (CRC) screening, but are commonly used as a diagnostic test in other clinical settings. We performed a systematic review to assess performance characteristics of FOBT as a diagnostic test for clinical indications.

METHODS

Bibliographic databases were searched to identify studies in adult patients with a specific gastrointestinal symptom or condition who underwent FOBT and a reference test and provided data on diagnoses. Our primary end point was sensitivity. Risk of bias was assessed with the QUADAS-2 tool.

RESULTS

Twenty-two studies met the inclusion criteria: 12 in iron deficiency anemia (IDA) (5 fecal immunochemical (FIT) and 7 guaiac based), 8 in ulcerative colitis (FIT), and 2 in acute diarrhea (guaiac based). Only 2 studies had low risk of bias on all domains of the QUADAS-2. On meta-analysis, FOBT had a sensitivity of 0.58 (95% confidence interval [CI] 0.53-0.63) and a specificity of 0.84 (95% CI 0.75-0.89) in predicting presumptive causes of IDA at endoscopy, with comparable results for guaiac-based tests and FIT. Sensitivity was higher for CRC (0.83) than non-CRC lesions (0.54). FIT had a sensitivity of 0.72 (95% CI 0.57-0.84) and a specificity of 0.80 (95% CI 0.67-0.89) in predicting endoscopic activity in UC. Sensitivities of FOBT for positive stool culture in acute diarrhea were 0.38 and 0.87.

DISCUSSION

Sensitivity of FOBT is poor for IDA: 42% of patients with identifiable causes of IDA had false-negative FOBT. Our results did not show acceptable performance characteristics for FOBT to guide decisions regarding endoscopic evaluation and do not support its use in IDA.

Risk of Oral and Upper Gastrointestinal Cancers in Persons With Positive Results From a Fecal Immunochemical Test in a Colorectal Cancer Screening Program

BACKGROUND & AIMS

European guidelines recommend screening for colorectal cancer (CRC) using the fecal immunochemical test (FIT), with follow-up colonoscopies for individuals with positive test results. However, more than half of participants with positive results from the FIT are not found to have advanced neoplasia in the colonoscopy examination. Fecal occult blood might also come from the upper gastrointestinal (GI) tract, so perhaps we should consider esophagogastroduodenoscopy (EGD), to detect upper GI cancers. We aimed to determine how many individuals are found to have oral or upper GI cancers (oral cavity, throat, esophageal, gastric, or small bowel cancer) within 3 years after a positive or negative result from a FIT in a CRC screening program.

METHODS

We performed a retrospective analysis of data from a pilot study of 3 rounds of biennial FIT-based screening for CRC in 2 regions in the west of the Netherlands, from 2006 through October 2012. Participants who developed oral or upper GI cancers were identified through linkage with the National Cancer Registry. We classified these cancers into 3 groups: those that developed in individuals with a positive result from a FIT but negative findings from colonoscopy (no advanced neoplasia), those that developed in individuals with a positive result from a FIT and a positive finding from colonoscopy (advanced neoplasia), and those that developed in individuals with negative results from a FIT. We compared oral and upper GI cancer incidence among groups.

RESULTS

Among 16,165 screening participants, linkage identified 52 persons who developed an oral or upper GI cancer within 3 years after a FIT. We found no significant difference in incidence values between individuals with a positive vs a negative FIT result: 8 cancers developed in individuals with a positive result from a FIT (0.37%; 95% CI, 0.19-0.76) and 44 developed in individuals with a negative result from a FIT (0.31%; 95% CI, 0.23-0.42) (P = .65). Of the 8 individuals with a positive result from a FIT and an oral or upper GI cancer, 6 were diagnosed after negative findings from colonoscopy and 2 after positive findings from colonoscopy. We found that only 0.14% of all persons with a positive result from a FIT were diagnosed with a gastric or esophageal cancer within 3 years.

CONCLUSION

In a study of individuals in the Netherlands undergoing screening for CRC by FIT, we found fewer than 1% of patients with a positive result from the FIT to receive a diagnosis of upper GI cancers within 3 years. Routine EGD investigation of individuals with positive results from a FIT and negative findings from colonoscopy is therefore not recommended. TrialRegister.nl, Number: NTR5385.

Recommendations on Fecal Immunochemical Testing to Screen for Colorectal Neoplasia: A Consensus Statement by the US Multi-Society Task Force on Colorectal Cancer

The use of the fecal occult blood test (FOBT) for colorectal cancer (CRC) screening is supported by randomized trials demonstrating effectiveness in cancer prevention and widely recommended by guidelines for this purpose. The fecal immunochemical test (FIT), as a direct measure of human hemoglobin in stool has a number of advantages relative to conventional FOBT and is increasingly used relative to that test. This review summarizes current evidence for FIT in colorectal neoplasia detection and the comparative effectiveness of FIT relative to other commonly used CRC screening modalities. Based on evidence, guidance statements on FIT application were developed and quality metrics for program implementation proposed.

Is gastroscopy for fecal immunochemical test positive patients worthwhile?

BACKGROUND

The use of fecal immunochemical test (FIT) in the screening for colorectal cancer is long established. However, more than 50 % of patients with positive FITs have a negative colonoscopy. The role of a subsequent oesophago-gastro-duodenoscopy (OGD) is debatable. The aim of this study is to evaluate the yield of OGD in patients with positive FITs.

METHODOLOGY

A retrospective review of patients who underwent colonoscopy for a positive FIT between Jan. 2008 and Dec. 2012 was identified from a prospectively collected endoscopy database at the National University Hospital, Singapore. Patients who underwent concurrent or subsequent OGDs for positive FIT formed the study group. We considered any new cancer or significant upper gastrointestinal pathology such as peptic ulcer disease or gastritis requiring treatment as a positive examination.

RESULTS

A total of 202 patients underwent both a colonoscopy and an OGD for a positive FIT and formed the study group. One hundred and six (52.5 %) of them had a positive examination with gastritis and duodenitis representing the most common UGI pathology in 89 (44.1 %) patients. Twenty-nine (14.4 %) patients tested positive for helicobacter pylori infection and another 16 (7.9 %) patients had peptic ulcer disease. There were no UGI cancers detected. One patient had an esophageal leiomyoma that was treated conservatively.

CONCLUSION

Routine gastroscopy for FIT positivity has a high diagnostic yield for benign upper gastrointestinal pathology. Well-designed prospective studies to further evaluate the cost-effectiveness of routine gastroscopy in the work up of FIT positivity are warranted to make better clinical practice guidelines.

Recommendations on Fecal Immunochemical Testing to Screen for Colorectal Neoplasia: A Consensus Statement by the US Multi-Society Task Force on Colorectal Cancer

The use of the fecal occult blood test (FOBT) for colorectal cancer (CRC) screening is supported by randomized trials demonstrating effectiveness in cancer prevention and widely recommended by guidelines for this purpose. The fecal immunochemical test (FIT), as a direct measure of human hemoglobin in stool has a number of advantages relative to conventional FOBT and is increasingly used relative to that test. This review summarizes current evidence for FIT in colorectal neoplasia detection and the comparative effectiveness of FIT relative to other commonly used CRC screening modalities. Based on evidence, guidance statements on FIT application were developed and quality metrics for program implementation proposed.

Effect of aspirin and antiplatelet drugs on the outcome of the fecal immunochemical test

OBJECTIVE

To evaluate the effect of aspirin and nonaspirin antiplatelet agents (NAAAs) on the performance of the fecal immunochemical test (FIT).

PARTICIPANTS AND METHODS

We performed a post hoc analysis of results from a clinical trial that involved 28,696 asymptomatic average-risk men and women aged 50 to 69 years invited to participate in a colorectal cancer screening program with FIT between November 1, 2008, and June 31, 2011.

RESULTS

The test was returned by 6390 individuals (22.3%), of whom 5821 (91.1%) reported not using antiplatelet drugs (nonusers group) and 569 (8.9%) reported using these drugs at the time of testing (users group). The FIT result was positive in 48 of 569 users (8.4%) and 365 of 5821 nonusers (6.3%) (P=.05). A positive FIT result was found in 7.3% (28/384) of aspirin users, 7.1% (10/140) of NAAA users, and 22.2% (10/45) of those undergoing dual antiplatelet therapy (DAPT) (aspirin plus an NAAA). The DAPT subgroup had a significantly higher positive FIT rate than the nonuser group (odds ratio, 3.5; 95% CI, 1.7-7.3; P<.05). The positive predictive value (PPV) for advanced neoplasia (AN) in nonusers was 50.4% vs 50.0% in users (P = .40). The PPV for AN was 57.0% in aspirin users, 30.0% in NAAA users, and 50.0% in DAPT users, without statistically significant differences between the user and nonuser groups.

CONCLUSION

The use of DAPT increased the rate of positive FIT results. Use of aspirin, NAAAs, or both did not modify the PPV for AN in this population-based colorectal screening program.

Esophago-gastro-duodenoscopy is not indicated in patients with positive immunochemical test and nonexplanatory colonoscopy

OBJECTIVES

Patients with positive fecal occult blood test and unrevealing colonoscopy are often advised to undergo esophago-gastro-duodenoscopy (EGD) to exclude a bleeding source in the upper gastrointestinal tract. In this study, we evaluated EGD findings in patients with positive immunochemical fecal occult blood test (I-FOBT) not explained by colonoscopy.

METHODS

Out of 1221 consecutive patients having total colonoscopy after preparing I-FOBT (OC-MICRO, with threshold of 75 or 100 ngHb/ml), we included only patients without colorectal cancer or advanced adenomatous polyp on colonoscopy, who also underwent EGD within 4 months of the fecal blood testing. Findings on EGD were classified as those lesions which are likely or unlikely to bleed.

RESULTS

EGD was performed in 160 patients after a negative colonoscopy. The procedure was performed 1.6 ± 1.4 months after the I-FOBT. Lesion with a bleeding potential was found in 24 patients (15%). In three (12.5%) and two (8.3%) of these patients I-FOBT was positive at the 75 and 100 ngHb/ml threshold, respectively. In 136 patients EGD was normal, and I-FOBT was similarly positive in 16 (11.7%) and 13 patients (9.5%), respectively. The mean fecal hemoglobin was also similar between the groups.

CONCLUSION

Immunological FOBT positivity was not correlated with the finding of lesions, which are likely to bleed on EGD. Thus, EGD is probably not indicated in patients with positive I-FOBT and unrevealing colonoscopy.

Sensitivity, but not specificity, of a quantitative immunochemical fecal occult blood test for neoplasia is slightly increased by the use of low-dose aspirin, NSAIDs, and anticoagulants

OBJECTIVES

We evaluated the effect of the use of aspirin, nonsteroidal anti-inflammatory drugs (NSAIDS), and anticoagulants on the performance of immunochemical fecal occult blood test (I-FOBT).

METHODS

A prospective, cross-sectional study of 1,221 ambulatory patients having total colonoscopy after preparing three I-FOBTs. Information regarding the use of medications was collected from the health medical organization (HMO) database. I-FOBT was analyzed with the OC-MICRO instrument using both >or=75 and 100 ngHb/ml of buffer thresholds to determine positivity.

RESULTS

Colorectal cancer (CRC) was found in 17 and advanced adenomatous polyp (AAP) in 97 patients. A total of 212 patients were using aspirin/NSAIDS at the time of I-FOBT testing. Qualitative analysis for the detection of AAP/CRC reveals a trend for an increased sensitivity with aspirin/NSAIDS use. At the threshold 75 ng/ml for positivity, the sensitivity for the detection of AAP/CRC was 66.7% for aspirin/NSAIDS use vs. 51.2% for nondrug takers (P=0.20), and at the threshold of 100 ng/ml, the sensitivity was 66.7 vs. 46.5% (P=0.09). The specificity, however, was not affected by the use of aspirin/NSAIDS. At the threshold of 75 ng/ml for positivity, the specificity for the detection of AAP/CRC was 89.5% for aspirin/NSAIDS use vs. 91.2% for nondrug takers (P=0.47), and at the threshold of 100 ng/ml, the specificity was 92.17 vs. 93.0% (P=0.69). A total of 33 patients were using antithrombotics/coagulants at the time of I-FOBT testing. This group was small; however, it appears that their use was also associated with a trend for increased sensitivity and no change in specificity.

CONCLUSIONS

The use of aspirin/NSAIDS and anticoagulants was associated with a trend for increased sensitivity with no change in specificity for the detection of AAP/CRC. This study suggests that there is no need to stop these agents before I-FOBT testing.

Positive rate comparison between immunological and chemical methods of fecal occult blood test in upper digestive tract bleeding

AIM: To compare the positive rates of immune fecal occult blood test (IFOBT) and chemical fecal occult blood test (CFOBT) in screening upper digestive tract bleeding.

METHODS: A total of 206 consecutive patients who suffered upper digestive tract bleeding and underwent endoscopic examination in our hospital were chosen from July 2006 to March 2007. CFOBT (using o-toluidine) and IFOBT were used to detect fecal occult blood positive rate in the same fecal specimen, and comparison was made between the two methods. The positive rates were also analyzed combined with the clinical data.

RESULTS: The results of IFOBT and CFOBT were not associated with anatomic sites in esophageal and gastric cancer, but associated with the invasion depth in gastric cancer, and they were positively correlated with the largest diameter of gastric cancer (IFOBT: r = 0.30, P = 0.02; CFOBT: r = 0.20, P = 0.04). Meanwhile, IFOBT result showed a positive correlation with the largest diameter of esophageal cancer (r = 0.38, P = 0.01). The positive rate of CFOBT was superior to that of squamous cell carcinoma (SCC) antigen detection in esophageal cancer patients (47.43% vs 20.45%, P < 0.05), and the positive rates of both methods were higher than those of CA125, CEA and CA199 detection. CFOBT was superior to IFOBT in detecting gastric cancer, esophageal cancer, reflux esophagitis and peptic ulcer (50.88% vs 35.09%; 47.73% vs 29.55%; 18.00% vs 6.00%; 60.00% vs 41.82%; all P < 0.05). The total positive rate of IFOBT was lower than that of CFOBT in detecting upper digestive tract bleeding.

CONCLUSION: The IFOBT is not suitable for screening upper digestive tract diseases, but relatively specific for lower digestive tract bleeding.

A comparative study of three fecal occult blood tests in upper gastrointestinal bleeding

The purpose of this study was to evaluate the performance characteristics of three fecal occult blood tests (FOBTs): the chemical o-toluidine test, the immunochemical OC-Hemodia test, and the immunochromatographic Quick Chaser Occult Blood (QCOB) test, which detect human hemoglobin and transferrin simultaneously in cases of upper gastrointestinal (GI) bleeding. Included were 48 FOBT specimens in 48 consecutive admission cases of upper GI bleeding (endoscopy confirmed). We excluded those fecal specimens with an obvious tarry and bloody appearance. The QCOB test revealed the highest positive rates of 33/48 (68.8%), and significantly higher positive rates than that of the OC-Hemodia test and o-toluidine test (p < 0.025 and < 0.01, respectively). In the patient group with upper GI bleeding due to gastric and duodenal ulcers, the QCOB test had higher positive rates (68.6%) than did the o-toluidine test (34.3%) (p < 0.01). There was no fecal specimen that was positive for the o-toluidine test or OC-Hemodia test and was negative for the QCOB test. Our results reveal that the QCOB test has significantly higher positive rates of fecal occult blood than either the OC-Hemodia test or o-toluidine test. The QCOB test is better than the other two tests for detecting occult blood in patients with upper GI bleeding.

Detection of occult upper gastrointestinal tract bleeding: performance differences in fecal occult blood tests

OBJECTIVE

To compare rates of detection of occult upper gastrointestinal (GI) tract bleeding by guaiac (Hemoccult II [HO]), immunochemical (HemeSelect [HS]), and heme-porphyrin (HemoQuant [HQT]) fecal occult blood tests. PATIENTS, SUBJECTS, AND METHODS: In a cross-sectional study to detect native occult upper GI tract bleeding, single stools were collected from 56 patients with iron deficiency and a proven hemorrhagic GI tract lesion. In a longitudinal study to detect simulated occult upper GI tract bleeding, 3 stool samples were serially collected from 10 clinically normal subjects after ingestion of 5 and 15 mL of autologous blood. All stool samples were subjected to blinded fecal occult blood determinations with use of the 3 tests.

RESULTS

In the cross-sectional study, the HQT test detected 88% (37/42) of hemorrhagic upper GI tract lesions compared with 26% (11/42) detected by the HO test (P<.001) and 2% (1/42) by the HS test (P<.001). In the longitudinal study, all preingestion fecal occult blood test results were negative. After ingestion of 5 mL of blood, the HQT result became positive in 60% (6/10), and the HO and HS results remained negative (P=.03). After ingestion of 15 mL of blood, the HQT result became positive in all 10 cases, the HO result was positive in 6 (P=.12 vs HQT), and the HS result was positive in none (P=.002 vs HQT); all 3 stool samples collected after the 15-mL ingestion were positive in each of the 10 subjects by the HQT test but in only 1 subject by the HO test (P=.003).

CONCLUSION

The HQT test detects occult upper GI tract blood loss significantly more frequently than the HO or HS test.