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

Diet and Genetic Risk Factors of Colorectal Cancer in Palestine: A Case-Control Study

To add evidence to the limited data available on colorectal cancer (CRC) from Palestine, we examine the risk factors associated with CRC using a matched hospital-based case-control study. A structured questionnaire was used to collect data from 105 cases and 105 controls. A multivariable conditional regression model was used to adjust for the association between study factors and CRC risk. In the model, compared with controls, cases from villages were significantly less likely to have CRC (Adjusted Odds Ratio, AOR = 0.194); taking aspirin lowered the likelihood of CRC by 24%; and having a multiple birth sibling by 33%. Also, the likelihood of CRC was lowered significantly by consuming five servings of fruits/vegetables per week or more (5-6 servings: AOR = 0.21, 7-8 servings per week: AOR = 0.04). However, cases had a significantly higher likelihood of CRC if they consumed 2-4 servings of grilled red meat per week (AOR = 4.25); smoked (AOR = 4.38); had a sedentary lifestyle (AOR = 2.53); reported parental consanguinity (AOR = 3.88); or had a family history of cancer (AOR = 6.39). Our results confirmed the association between CRC and red meat intake and smoking, and proved that parental consanguinity and family history of cancer are also risk factors for CRC.

In vitro Validation Assessment of a Fecal Occult Blood Protein Test for Horses

A commercially available equine fecal blood test (FBT) claims to be able to detect the presence of blood proteins (albumin and hemoglobin) in manure. The purpose of this study was to determine the FBT test sensitivity, specificity, positive and negative predictive values (PPV, NPV), lower threshold of detection, time to obtain a visual positive result, effect of temperature and result stability in lab and field conditions. The FBT was assessed for its sensitivity and specificity for detecting pure albumin and hemoglobin at two temperatures over a range of concentrations. Time to result was measured for up to 60 minutes. PPV and NPV were assessed by measuring albumin and hemoglobin in manure from 13 pleasure horses over 25 days. Laboratory tests of hemoglobin alone, albumin alone, and hemoglobin and albumin combined were tested over a range of concentrations from 0.0125 ppm to 50 ppm. In the field study, fresh (within 30 minutes) manure was sampled and tested for proteins using the FBT. The FBT was both sensitive and specific to hemoglobin and albumin. The effect of cold temperature on time to a positive result at 15 minutes was not significant. Results were stable for up to 60 minutes. The field study showed evidence that the appearance of blood proteins in manure was intermittent, and that three tests on consecutive days provided a much better PPV and NPV. It is concluded that this FBT had high specificity, sensitivity, PPV, NPV, was equally functional at low and moderate temperatures, provided a rapid (within 15 minutes) and stable (for up to 60 minutes) reading. Its use in the field is simple and effective.

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.

Optimisation of a serum albumin removal protocol for use in a proteomic study to identify the protein biomarkers for silent gastric ulceration in horses

Silent gastric ulceration occurs without evidence of clinical signs and is common in horses. There is currently no a simple and effective method to diagnose this disease. Proteomics can be used to identify serum biomarkers, but the most abundant serum protein, albumin, could conceal candidate biomarkers. Therefore, it is recommended to remove albumin before a proteomic study; however, there is no specific albumin depletion kit or standard protocol available for horse samples. The objectives of this study were to optimise a protocol to remove equine serum albumin and to use albumin-depleted serum to identify the protein biomarkers for silent gastric ulceration. Gastroscopy was used to identify gastric ulceration, and serum was obtained from horses with either a healthy gastric mucosa or gastric ulceration. Serum albumin was removed using the trichloroacetic acid (TCA) protein precipitation method, and this protocol was optimised by varying the concentration of TCA, type of organic solvents, ratio of serum to protein precipitation solution, and incubation times. Electrophoresis and image analysis were used to compare the amounts of albumin, immunoglobulins G (IgG), and protein degradation before and after TCA precipitation. The best protocol was chosen to remove albumin for a proteomic study (electrophoresis and mass spectrometry). The results revealed that protocol 2 (ratio of serum to solution 1:5, 10% TCA in acetone, and 90 min incubation) was the most efficient protocol to remove albumin (98%) and IgG heavy (80%) and light (98%) chains without degrading other proteins. After electrophoresis and mass spectrometry analysis, KRT1, KRT6A and KRT18 were identified as potential markers for silent gastric ulceration.

Emergency diagnosis of upper gastrointestinal bleeding by detection of haemoglobin in nasogastric aspirate

OBJECTIVE

To determine the accuracy of the Faecal Occult Blood-Transferrin test (FOB-T; Certest Biotec, San Mateo de Gállego, Spain) for detection of blood in nasogastric aspirate, and its emergency diagnostic value for upper gastrointestinal bleeding (UGIB).

METHODS

Nasogastric aspirate was collected from patients with haematemesis on admission to hospital. Haemoglobin was quantified on admission and after 12 h. FOB-T test was used to assess each nasogastric aspirate sample for the presence of haemoglobin and transferrin.

RESULTS

Of 64 patients included in the study, 28 (43.8%) were hospitalized for UGIB based on physical examination, haemoglobin level. 24 were confirmed with endoscopy findings. Four were excluded from study due to lack of endoscopic confirmation. The remaining 36 patients had no clinical evidence of UGIB. FOB-T test findings were positive in 26/60 patients, including all 24 patients with UGIB. The FOB-T test had sensitivity 100%, specificity 94.4%, positive predictive value 92.3% and negative predictive value 100% for UGIB.

CONCLUSIONS

A negative FOB-T test may be sufficient to exclude the possibility of UGIB without other diagnostic tests.

Is esophagogastroduodenoscopy necessary in patients with positive fecal occult blood tests and negative colonoscopy?

BACKGROUND

False positives of fecal occult blood tests (FOBT) regarding colorectal cancer detection are common. The aim was to investigate the upper gastrointestinal (GI) condition confirmed by endoscopy in positive FOBT patients without advanced colorectal neoplasia, hemorrhoid, or colitis.

METHODS

The authors reviewed the collective data of 340 positive FOBT patients who underwent both esophagogastroduodenoscopy (EGD) and colonoscopy from January 2005 to October 2011. Demographic data, effects of medications, including antiplatelet agents, nonsteroidal anti-inflammatory drugs, or warfarin on the results of FOBT, presence or absence of GI mucosal lesions confirmed by EGD and colonoscopy, and FOBT titer in 552 positive FOBT patients were analyzed.

RESULTS

On colonoscopy, colorectal cancer was detected in 35 patients (10.3%), advanced adenoma in 22 patients (6.4%). "Negative colonoscopy" included no significant lesions and non-advanced adenomas. In 243 patients with "negative colonoscopy", EGD findings included 3 (1.2%) gastric cancers and 39 (16%) peptic ulcer diseases. Gastric cancers were all found in patients who had no experience of EGD within 2 years; however, the incidence of peptic ulcer disease was not different in patients with or without previous EGD within 2 years. Two or more antiplatelet agents increased false positive rates of FOBT.

CONCLUSIONS

Upper GI evaluation is mandatory in patients with positive FOBTs and negative colonoscopy especially in patients without experience of EGD within 2 years.

Colorectal cancer screening: Comparison of transferrin and immuno fecal occult blood test

AIM: To evaluate the sensitivity and specificity of transfesrrin dipstick test (Tf) in colorectal cancer (CRC) screening and precancerous lesions screening.

METHODS: Eight hundreds and sixty-one individuals at high-risk for CRC were recruited. Six hundreds and eleven subsequently received the three fecal occult blood tests and colonoscopy with biopsy performed as needed. Fecal samples were obtained on the day before colonoscopy. Tf, immuno fecal occult blood test (IFOBT) and guaiac fecal occult blood test (g-FOBT) were performed simultaneously on the same stool. To minimize false-negative cases, all subjects with negative samples were asked to provide an additional stool specimen for a second test even a third test. If the results were all negative after testing three repeated samples, the subject was considered a true negative. The performance characteristics of Tf for detecting CRC and precancerous lesions were examined and compared to those of IFOBT and the combination of Tf, IFOBT and g-FOBT.

RESULTS: A total of six hundreds and eleven subjects met the study criteria including 25 with CRC and 60 with precancerous lesions. Sensitivity for detecting CRC was 92% for Tf and 96% for IFOBT, specificities of Tf and IFOBT were both 72.0% (95% CI: 68.2%-75.5%; χ² = 0.4, P > 0.05); positive likelihood ratios of those were 3.3 (95% CI: 2.8-3.9) and 3.4 (95% CI: 2.9-4.0), respectively. In precancerous lesions, sensitivities for Tf and IFOBT were 50% and 58%, respectively (χ² = 0.8, P > 0.05); specificities of Tf and IFOBT were 71.5% (95% CI: 67.6%-75.1%) and 72.2% (95% CI: 68.4%-75.8%); positive likelihood ratios of those were 1.8 (95% CI: 1.3-2.3) and 2.1 (95% CI: 1.6-2.7), respectively; compared to IFOBT, g-FOBT+ Tf+ IFOBT had a significantly higher positive rate for precancerous lesions (83% vs 58%, respectively; χ² = 9.1, P < 0.05). In patients with CRC and precancerous lesions, the sensitivities of Tf and IFOBT were 62% and 69% (χ² = 0.9, P > 0.05); specificities of those were 74.5% (95% CI: 70.6%-78.1%) and 75.5% (95% CI: 71.6%-79.0%); positive likelihood ratios of those were 2.5 (95% CI: 2.0-3.1) and 2.8 (95% CI: 2.3-3.5). Compared to IFOBT alone, combining g-FOBT, IFOBT and Tf led to significantly increased sensitivity for detecting CRC and cancerous lesions (69% vs 88%, respectively; χ² = 9.0, P < 0.05).

CONCLUSION: Tf dipstick test might be used as an additional tool for CRC and precancerous lesions screening in a high-risk cohort.

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.

Transferrin dipstick as a potential novel test for colon cancer screening: a comparative study with immuno fecal occult blood test

Recent proteomic studies identified Transferrin (Tf) as a potential biomarker for cancer. We examined the efficacy of the newly developed Tf dipstick for detecting colorectal cancer and premalignant lesions, and compared that to Immuno Fecal Occult Blood test (IFOBT). Fecal samples from 110 patients including 40 colorectal cancer, 36 premalignant subjects (including 16 with high-risk adenomas and 20 with ulcerative colitis), and 34 low-risk subjects were collected before colonoscopic examination. Compared with IFOBT, Tf had a significantly higher positive rate in patients with colorectal cancer and premalignant lesions (76% for Tf versus 61% for IFOBT, respectively; chi(2) = 4.38; P < 0.05). The difference of positivity was mainly observed in patients with premalignant lesions (72% for Tf versus 44% for IFOBT; chi(2) = 5.71; P < 0.05), whereas the positive rates in cancer group and in low-risk group were similar (both P > 0.05). Combining Tf with IFOBT together (either/or) had 90% positive rate in cancer patients, 78% in premalignant patients, and 29% in low-risk subjects. The overall accuracy of IFOBT and Tf tests for detecting colorectal cancer and premalignant lesion was 69.0% and 76.4%, respectively. Tf dipstick test seems to be a highly sensitive test for detecting not only cancer, but also premalignant lesions, and provides an additional tool for colorectal cancer screening.

Cutoff value determines the performance of a semi-quantitative immunochemical faecal occult blood test in a colorectal cancer screening programme

Background:

The cutoff of semi-quantitative immunochemical faecal occult blood tests (iFOBTs) influences colonoscopy referrals and detection rates. We studied the performance of an iFOBT (OC-Sensor) in colorectal cancer (CRC) screening at different cutoffs.

Methods:

Dutch screening participants, 50–75 years of age, with average CRC risk and an iFOBT value ⩾50 ng ml⁻¹ were offered colonoscopy. The detection rate was the percentage of participants with CRC or advanced adenomas (⩾10 mm, ⩾20% villous, high-grade dysplasia). The number needed to scope (NNTScope) was the number of colonoscopies to be carried out to find one person with CRC or advanced adenomas.

Results:

iFOBT values ⩾50 ng ml⁻¹ were detected in 526 of 6157 participants (8.5%) and 428 (81%) underwent colonoscopy. The detection rate for advanced lesions (28 CRC and 161 with advanced adenomas) was 3.1% (95% confidence interval: 2.6–3.5%) and the NNTScope was 2.3. At 75 ng ml⁻¹, the detection rate was 2.7%, the NNTScope was 2.0 and the CRC miss rate compared with 50 ng ml⁻¹ was <5% (N=1). At 100 ng ml⁻¹, the detection rate was 2.4% and the NNTScope was <2. Compared with 50 ng ml⁻¹, up to 200 ng ml⁻¹ CRC miss rates remained at 16% (N=4).

Conclusions:

Cutoffs below the standard 100 ng ml⁻¹ resulted in not only higher detection rates of advanced lesions but also more colonoscopies. With sufficient capacity, 75 ng ml⁻¹ might be advised; if not, up to 200 ng ml⁻¹ CRC miss rates are acceptable compared with the decrease in performed colonoscopies.

False negative fecal occult blood tests due to delayed sample return in colorectal cancer screening

Delayed return of immunochemical fecal occult blood test (iFOBT) samples to a laboratory might cause false negatives because of hemoglobin degradation. Quantitative iFOBT's became increasingly more accepted in colorectal cancer screening. Therefore, we studied the effects of delay between sampling and laboratory delivery on iFOBT performance. IFOBT positivity (>or=50 ng/ml hemoglobin) in colorectal cancer screening participants without delay between sampling and laboratory delivery (<5 days), was compared with positivity in participants with >or=5 and >or=7 days delay. Additionally, positive tests were stored at room temperature and retested 5 times within 10-14 days. The sampling date was reported by 61% (n = 3,767) of the participants: in 19% delay was >or=5 days and in 5% >or=7 days. Compared with no-delay, the adenoma detection rate was already significantly decreased after >or=5 days delay (OR 0.6; 95%CI 0.4-0.9). We retested iFOBT samples of 170 positives of which 139 (82%) had a colonoscopy: 45 (32%) had advanced adenomas (not colorectal cancer) and 8 (6%) had colorectal cancer. Mean daily fecal hemoglobin decrease was 29 ng/ml (S.D. 38 and median 11 ng/ml). In patients with advanced adenomas, hemoglobin in the sample was <50 ng/ml in 5 (11%) 2-3 days after the initial test and in 16 (36%) after 10-14 days. Seven days after the initial test, 2 (25%) colorectal cancer patients became false negative. Both had stage I colorectal cancer and initial values below 100 ng/ml, where the average for stage I is 532 ng/ml. Delay in sample return increased false negative immunochemical FOBT's. Mainly precursor lesions, but also colorectal cancer, will be missed due to delayed sample return.

Random comparison of guaiac and immunochemical fecal occult blood tests for colorectal cancer in a screening population

BACKGROUND & AIMS

Despite poor performance, guaiac-based fecal occult blood tests (G-FOBT) are most frequently implemented for colorectal cancer screening. Immunochemical fecal occult blood tests (I-FOBT) are claimed to perform better, without randomized comparison in screening populations. Our aim was to randomly compare G-FOBT with I-FOBT in a screening population.

METHODS

We conducted a population-based study on a random sample of 20,623 individuals 50-75 years of age, randomized to either G-FOBT (Hemoccult-II) or I-FOBT (OC-Sensor). Tests and invitations were sent together. For I-FOBT, the standard cutoff of 100 ng/ml was used. Positive FOBTs were verified with colonoscopy. Advanced adenomas were defined as >or=10 mm, high-grade dysplasia, or >or=20% villous component.

RESULTS

There were 10,993 tests returned: 4836 (46.9%) G-FOBTs and 6157 (59.6%) I-FOBTs. The participation rate difference was 12.7% (P < .01). Of G-FOBTs, 117 (2.4%) were positive versus 339 (5.5%) of I-FOBTs. The positivity rate difference was 3.1% (P < .01). Cancer and advanced adenomas were found, respectively, in 11 and 48 of G-FOBTs and in 24 and 121 of I-FOBTs. Differences in positive predictive value for cancer and advanced adenomas and cancer were, respectively, 2.1% (P = .4) and -3.6% (P = .5). Differences in specificities favor G-FOBT and were, respectively, 2.3% (P < .01) and -1.3% (P < .01). Differences in intention-to-screen detection rates favor I-FOBT and were, respectively, 0.1% (P < .05) and 0.9% (P < .01).

CONCLUSIONS

The number-to-scope to find 1 cancer was comparable between the tests. However, participation and detection rates for advanced adenomas and cancer were significantly higher for I-FOBT. G-FOBT significantly underestimates the prevalence of advanced adenomas and cancer in the screening population compared with I-FOBT.