Diagnostic value of occult fecal blood testing for colorectal cancer screening

AIM: To evaluate the diagnostic value of occult fecal blood testing in mass colorectal cancer screening.METHODS: A reverse passive hemagglutination reaction fecal occult blood test (RPHA-FOBT) and colorectal cancer risk factor quantitative method were used as preliminary screening for colorectal cancer. A 60-cm fiber optic colonoscopy was used to validate the preliminary screen and was used to detect colorectal cancer in a community of 75813 subjects.RESULTS: Compared to the 60-cm fiber optic colonoscopy as a standard reference, FOBT has a sensitivity of 41.9%, specificity of 95.8%, Youden′s index of 0.38, and positive predictive value of 0.68%. These results increased with subject age from the first detection. A 3-year follow up in the target mass showed that all new cases had initially been FOBT-negative.CONCLUSION: The value of FOBT as an indicator of colorectal cancer in mass screening is limited.     

Fecal occult blood testing for colorectal cancer screening: use the finger

OBJECTIVE: Fecal occult blood testing (FOBT) has been widely underused as a means of colorectal cancer screening. Less than 35% of Americans have had the recommended FOBT in the last 5 yr. Guidelines suggest FOBT of three spontaneously passed stools (SPS) on a prescribed diet. Testing stool obtained by digital rectal exam (DRE) is discouraged because its yield in colorectal cancer screening is unknown. The aim of this study is to compare the positive predictive value of FOBT for the detection of colorectal neoplasia done by SPS versus DRE in asymptomatic outpatients. METHODS: Medical records and endoscopic reports of all patients who underwent colonoscopy between 1984-1999 for a positive FOBT were reviewed. Only asymptomatic outpatients whose indication was colorectal cancer screening were included. The method of FOBT was confirmed as either SPS or DRE. Chi2 was used to compare the yield of detecting colorectal neoplasia between SPS and DRE. RESULTS: A total of 165 patients with a mean age of 61 yr (range 33-85) were included (84 patients were women). Neoplasia was detected in 29 of 80 (36%) with SPS and 28 of 85 (33%) with DRE (p = 0.18). CONCLUSIONS: The positive predictive value of FOBT on DRE for detecting neoplasia is similar to that of SPS in asymptomatic outpatients undergoing colorectal cancer screening. Positive FOBT on DRE warrants colonoscopic evaluation. Hemoccult testing by DRE may be performed in the office to increase patient compliance with colorectal cancer screening. A negative FOBT on DRE should be followed up with FOBT of SPS.     

Evaluation of a fecal occult blood test with reverse passive hemagglutination for colorectal neoplasm screening

AIM: To evaluate the one and three sampling reverse passive hemagglutination fecal occult blood test (RPHA FOBT) for colorectal neoplasm screening.METHODS: A group of 3034 individuals with histories of colorectal polyps and/or ulcers were screened for colorectal cancer. Three day fecal samples were collected and 60 cm fiberoptic colonoscopy was conducted for each subject. The fecal samples were tested for occult blood with the RPHA method and the endoscopic and histopathological diagnoses were used as standard reference for evaluation. The sensitivity, specificity and positive and negative predictive values of different samplings were compared.RESULTS: About 521 cases of colorectal neoplasms were detected, including 12 cases of colorectal cancer and 509 cases of polyps. Results showed that the mean sensitivity of one sampling RPHA FOBT for colorectal neoplasm was only 13.2%, the specificity was 90.3% and the positive and negative predictive values were 21.3% and 83.4%, respectively; while for the three sampling, taking one positivity as positive, the sensitivity increased to 22.0%, the specificity decreased to 81.6% and the positive and negative predictive values were 19.7% and 83.6%, respectively.CONCLUSION: A single RPHA FOBT seems to be less sensitive for screening for colorectal neoplasms. Since it is convenient and economical, RPHA FOBT remains the most practical procedure for detection of early colorectal cancer and polyps if it is combined with other screening methods.     

Immunological fecal occult blood test vs. serum ferritin for detection of colorectal neoplasia in high risk asymptomatic population

Introduction: Fecal occult blood tests (FOBT) (biochemical or immunological) are based on the fact that most of the polyps or cancers bleed. Anemia due to iron deficiency is a wellknown sign for colorectal cancer (CRC). Ferritin is frequently used to select candidates for colonoscopy. Objective: To determine and compare the diagnostic value of immunological fecal occult blood test vs. ferritin for the detection of colorectal neoplasia (cancer or polyps) in high-risk patients. Methods: A transversal prospective study at National Cancer Institute, Mexico City, in consecutive asymptomatic subjects at high risk for CRC was performed, comparing two tests (immunological against serum ferritin) with colonoscopy plus histopathology. Both tests were performed in a blindly fashion previous to colonoscopy. Results: Fifty patients were included in the study; twenty-eight patients had colorectal neoplasia (21 CRC, 7 adenomas). All immunologic tests for fecaloccult blood were positive in patients with colorectal lesions (sensitivity, 98%). There was no difference between the mean ferritin levels in patients with CRC or adenomas vs. those with negative colonoscopy (p = 0.58). The cutoff point where significant relationship between serum ferritin levels and colon lesions was established was ?46 ng/mL. In anemic patients with serum ferritin levels <46 ng/mL, the test had a sensitivity 53%, specificity 86%, positive predictive value 83%, and negative predictive value of 59% (p = 0.003). Conclusions: The immunological FOBT is a better diagnostic tool than serum ferritin for screening of colonic neoplasms.     

Positive predictive value of fecal occult blood testing in persons taking warfarin

BACKGROUND: In clinical practice, some physicians discontinue warfarin prior to fecal occult blood testing (FOBT). Although anticoagulant use is associated with an increased risk of overt gastrointestinal bleeding, the impact of warfarin on the positive predictive value of FOBT is unknown. METHODS: During a 5-yr period, we prospectively studied all patients taking warfarin who were referred for the evaluation of a positive FOBT. For each patient taking warfarin, we enrolled one age- and gender-matched control subject with a positive FOBT who was not taking anticoagulants. A detailed clinical history was obtained, and all subjects underwent colonoscopy and esophagogastroduodenoscopy. RESULTS: Lesions consistent with occult bleeding were identified in 59.0% of the 210 patients in the warfarin group and 53.8% of the 210 control subjects (p= 0.27). Although more lesions were identified by colonoscopy in the warfarin group than in control subjects (36.2%vs 25.7%, p= 0.02), there was no difference in the frequency of lesions identified by esophagogastroduodenoscopy (35.2%vs 39.5%, p= 0.43). Overall, adenomas > or =1 cm in diameter (16.2%) and colorectal carcinoma (9.5%) were the most common lesions identified by colonoscopy, while erosive gastritis (15.5%) and erosive duodenitis (11.0%) were the most frequent lesions found by esophagogastroduodenoscopy. Among individuals with colorectal cancer, 83.3% of patients in the warfarin group had early cancers (Dukes' stage A or B) compared with 50.0% of control subjects (p= 0.046). CONCLUSIONS: Warfarin use did not decrease the positive predictive value of FOBT. These findings suggest that warfarin should not be discontinued prior to FOBT.     

Digital rectal examination sampling of stool is less predictive of significant colorectal pathology than stool passed spontaneously

OBJECTIVES: To compare the positivity rate and the positive predictive value of an immunochemical faecal occult blood test (FOBT) carried out by using stool samples obtained during a routine screening method and those obtained during digital rectal examination. DESIGN: Screening programme-based, cross-sectional study. METHODS: In a screening programme-based, cross-sectional study, 1,044 subjects who received both an immunochemical FOBT and colonoscopy were divided into two groups according to stool collection techniques--the routine screening method and the digital rectal examination method. The positivity rate of the immunochemical FOBT, as well as the positive predictive value for colorectal cancer and large adenomatous polyp, were determined in the two groups. RESULTS: The positivity rate and positive predictive value were 3.8% and 60.0% (10.0% for cancer and 50.0% for adenomatous polyp) in the routine screening group, and 9.4% and 26.5% (4.1% for cancer and 22.4% for adenomatous polyp) in the digital rectal examination group, respectively, indicating a significant difference in the positivity rate (P < 0.01) as well as the positive predictive value (P< 0.05) between the two groups. CONCLUSIONS: These results show that digital rectal examination sampling of stool is less predictive of significant colorectal pathology than stool passed spontaneously, and therefore the latter is the preferred method for stool sampling.     

A comparison of the immunochemical fecal occult blood test and total colonoscopy in the asymptomatic population

BACKGROUND & AIMS: The fecal occult blood test (FOBT) is recommended as a screening test for colorectal cancer, but there are few reliable studies on the accuracy of immunochemical FOBT. The aim of this study was to analyze the sensitivity of immunochemical FOBT and to compare the results with the findings from complete colonoscopy. METHODS: Asymptomatic adults underwent 1-time immunochemical FOBT and total colonoscopy simultaneously. The prevalence and location of colorectal neoplasia were determined by colonoscopy. The results of immunochemical FOBT and the colonoscopic findings were compared. RESULTS: Of 21,805 patients, immunochemical FOBT was positive in 1231 cases (5.6%). The sensitivity of 1-time immunochemical FOBT for detecting advanced neoplasia and invasive cancer was 27.1% and 65.8%, respectively. In addition, the sensitivity for invasive cancer according to Dukes' stage showed 50.0% for Dukes' stage A, 70.0% for Dukes' stage B, and 78.3% for Dukes' stages C or D. The sensitivity for detecting advanced neoplasia at the proximal colon was significantly lower than that detected in the distal colon (16.3% vs 30.7%, P = .00007). CONCLUSIONS: Although the screening of asymptomatic patients with immunochemical FOBT can identify patients with colorectal neoplasia to a certain extent, the sensitivity is relatively low and different according to the tumor location. Therefore, programmatic and repeated screening by immunochemical FOBT may be necessary to increase sensitivity for colorectal cancer detection.     

Feasibility study of colorectal cancer screening by immunochemical faecal occult blood testing: results in a northern Italian community

AIM: Screening by means of faecal occult blood testing (FOBT) has proved to be effective in reducing colorectal cancer incidence and mortality. We performed a pilot screening for colorectal cancer by latex immunological FOBT in two municipalities of the region Valle d'Aosta, Italy, focusing on problems and obtaining indications for the feasibility and extension of the screening programme on a regional basis. METHODS: A total of 2961 subjects aged 50-74 years were invited by mail to perform a one-day immunochemical FOBT without any dietary restrictions and with a positive threshold put at 100 ng/ml. Patients with positive tests were then invited to undergo colonoscopy and double-contrast barium enema if colonoscopy was incomplete. RESULTS: A total of 1631 subjects performed the screening test with an overall compliance of 55.1%. Seventy-two subjects had a positive FOBT. Detection rates for cancer and adenomas were 1.8 per thousand and 16.6 per thousand, respectively. Positive predictive values (PPVs) for cancer and adenomas were 4.5% and 40.3%, respectively. CONCLUSIONS: Screening had an adequate attendance rate and the majority of the indicators were satisfactory. The use of a one-day quantitative latex FOBT with no dietary restrictions, automation of the analytical procedure, and a positive threshold of 100 ng/ml has shown that a programme based on this test is feasible in both organizational and attendance terms. On the basis of this experience, the extension of the screening on a regional basis is suggested.     

Screening for colorectal cancer in Chinese: comparison of fecal occult blood test,flexible sigmoidoscopy,and colonoscopy

BACKGROUND AND AIMS: Fecal occult blood testing (FOBT), flexible sigmoidoscopy (FS), and colonoscopy are the most commonly recommended screening tests for colorectal cancer. The aim of this study was to compare the accuracy and safety of these 3 screening procedures in a general population of ethnic Chinese. METHODS: Asymptomatic adults older than 50 years were recruited from the general public through health exhibitions. All enrolled subjects were offered FOBT and full colonoscopy under sedation. Advanced colonic lesions (defined as adenoma > or = 10 mm, villous adenoma, adenoma with moderate or severe dysplasia, or invasive cancer) were recorded. Lesions at the distal 40 cm in the left colon and rectum were taken as findings of FS. RESULTS: A total of 505 subjects (56% women; mean age +/- SD, 56.5 +/- 5.4 years) were enrolled, and 476 (94.3%) had a complete colonoscopy. Advanced colonic neoplasms were documented in 63 subjects (12.5%), of which 45 had lesions in the distal colon and 26 in the proximal colon. Among the 385 subjects with a normal distal colon, 14 (3.6%) had advanced lesions in the proximal colon that would be missed by FS alone. The sensitivity and specificity of FOBT for advanced colonic lesions were 14.3% and 79.2% and the sensitivity and specificity of FS were 77.8% and 83.9%, respectively. Combining FOBT with FS would not significantly improve the results of FS alone. Among these 505 subjects who underwent colonoscopy and 148 who underwent polypectomy, there was no perforation and only one occurrence of postpolypectomy bleeding recorded. CONCLUSIONS: Colonoscopy is a safe and accurate method for the screening of colorectal neoplasms in Chinese subjects.     

Virtual colonoscopy using oral contrast compared with colonoscopy for the detection of patients with colorectal polyps

BACKGROUND & AIMS: Virtual colonoscopy using abdominal spiral computed tomography scanning allows total colonic evaluation with minimal invasiveness. Two-dimensional images and selective 3-dimensional images of the colon are used to detect colorectal lesions. This trial used conventional colonoscopy with segmental unblinding to determine the ability of virtual colonoscopy to identify patients with colorectal lesions who need conventional colonoscopy. METHODS: We studied 205 patients with virtual colonoscopy using oral iodinated contrast preceding conventional colonoscopy. Colonic lavage was achieved with an oral sodium phosphosoda preparation and colonic distention with a carbon dioxide electronic insufflator. RESULTS: The overall sensitivity and specificity of virtual colonoscopy in identifying patients with colorectal lesions was 61.8% and 70.7%, respectively. Virtual colonoscopy was more accurate in identifying patients with lesions >/=6 mm (sensitivity 84.4% and specificity 83.1%) and those with lesions >/=10 mm (sensitivity 90% and specificity 94.6%). The negative predictive value of virtual colonoscopy was 95% for a 6-mm cutoff size and 98.9% for a 10-mm cutoff. Using a 10-mm cutoff, virtual colonoscopy precludes the need for conventional colonoscopy in 86% of patients with a 1% false-negative rate (68% with a 3.4% false-negative rate when using a 6-mm cutoff). CONCLUSIONS: Virtual colonoscopy has a high sensitivity and specificity for detecting patients with significant colorectal lesions. Its high negative predictive value may help reduce the number of negative screening colonoscopies. Further studies are needed to determine what lesion cutoff size is clinically acceptable and the appropriate interval time for repeat virtual colonoscopy when it detects lesions below this cutoff size.     

High resolution chromoendoscopy in the differential diagnosis of neoplastic and non-neoplastic polyps

BACKGROUND: Magnifying colonoscopy brought the possibility of precise histologic diagnosis of colorectal lesions through their surface appearance. Despite the high accuracy of magnifying colonoscopy it is a specialized and expensive equipment not available in most medical centers. Due to these reasons the use of conventional colonoscopy with chromoscopy has been raised because this produce can reproduce most of the information previously obtained by magnifying colonoscopy. AIM: To determine the role of high resolution colonoscopy and indigo carmine chromoscopy for differential diagnosis between neoplastic and non-neoplastic colorectal lesions through measurements of accuracy, sensitivity, specificity, positive and negative predictive values. PATIENTS / METHODS: It was performed a prospective study. Seventy-four colorectal polyps were evaluated in 54 patients. A high resolution Olympus Exera CFQ 160L colonoscope was used. After the identification of the lesions, they were dyed with indigo carmine 0,2% and classified according to Kudo's classification by a single observer. After resection, the polyps were submitted to histopathological examination. RESULTS: The endoscopic findings were compared to histopathologic results. The accuracy of the method was 79,7%, sensibility of 88,8%, specificity of 55%, positive predictive value of 84,2% and a negative predictive value of 64,7%. CONCLUSION: We can conclude that we must be careful to apply high resolution colonoscopy and chromoscopy because adenomatous lesions can be misdiagnosed as non-neoplastic.     

Magnetic resonance colonography versus conventional colonoscopy for the detection of colonic endoluminal lesions

BACKGROUND & AIMS: The most effective prophylaxis for colorectal cancer is endoscopic polypectomy. Prompted by the disadvantages of conventional colonoscopy (CC), we assessed the diagnostic ability of a promising alternative technique for detecting endoluminal masses: magnetic resonance colonography (MRC). METHODS: Seventy consecutive patients referred for CC underwent preliminary MRC. The diagnostic ability of this technique in detecting colonic endoluminal lesions was determined, compared with that of CC, and related to the findings from histologic examination. RESULTS: In detecting endoluminal lesions, MRC achieved a diagnostic accuracy similar to CC (sensitivity, 96%; specificity, 93%; positive predictive value, 98%; and negative predictive value, 87.5%). CONCLUSIONS: MRC could be useful in screening programs of patients at high risk for colon cancer. Patients with MRC-detected endoluminal lesions must undergo CC for histologic diagnosis.     

Comparison of an established simple office-based immunological FOBT with fecal tumor pyruvate kinase type M2 (M2-PK) for colorectal cancer screening: prospective multicenter study

OBJECTIVES: The immunological fecal occult blood test (IFOBT) has established itself as a more precise marker for colorectal cancer (CRC) screening than traditional guaiac-based FOBT. The simpler, cheaper, and more convenient newer office-based IFOBTs have been validated for diagnosing CRC. Dimeric isoenzyme of pyruvate kinase, M2-PK, expressed by tumor cells, has as well been proposed as a screening tool for CRC. This is the first study comparing fecal M2-PK as a screening biomarker for CRC against previously evaluated office-based IFOBT and colonoscopy.
METHODS: Six hundred forty consecutive subjects (symptomatic, as well as for CRC screening) referred for colonoscopy for various indications across five centers in Germany provided the stool samples for performing M2-PK and an immunochemical FOB strip test. The IFOBT used was a rapid immunochromatographic assay for detection of fecal hemoglobin. For M2-PK, a commercially available sandwich enzyme-linked immunosorbent assay (ELISA) was used. The M2-PK test needs 6 h, while the office-based test can be read in just 10 min and is five times cheaper.
RESULTS: Office-based IFOBT had sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and positive and negative likelihood ratios (LR) of 64.5, 96.3, 72.0, 94.9, 17.5, and 0.4 for diagnosing colorectal neoplasia (CRN), while the above performance characteristics for M2-PK at a cutoff value of 4U/mL were 72.4, 73.8, 29.0, 94.8, 2.8, and 0.8 respectively.
CONCLUSIONS: This office-based IFOBT was found to have significantly higher specificity, PPV, and positive LR as compared with M2-PK. IFOBT proved to be a convenient, noncumbersome, quick, and cheap tool in patients with above-average risk for detection of CRN.     

Prediction of synchronous colorectal cancers by computed tomography in subjects receiving an incomplete colonoscopy:A single-center study

AIM:To assess the value of computed tomography(CT)for diagnosis of synchronous colorectal cancers(SCRCs)involving incomplete colonoscopy.METHODS:A total of 2123 cases of colorectal cancer(CRC)were reviewed and divided into two groups according to whether a complete or incomplete colonoscopy was performed.CT results and final histological findings were compared to calculate the sensitivity and specificity associated with CT for detection of SCRCs following complete vs incomplete colonoscopy.Factors affecting the CT detection were also analyzed.RESULTS:Three hundred and seventy-four CRC patients underwent incomplete colonoscopy and 1749received complete colonoscopy.Fifty-six cases of SCRCs were identified by CT,and 36 were missed.In the incomplete colonoscopy group,the sensitivity and specificity of CT were 44.8%and 93.6%,respectively.The positive and negative predictive values were 23.6%and 95.0%,respectively.In contrast,the sensitivity and specificity of CT for the complete colonoscopy group were 68.3%and 97.0%,while the positive and negative predictive values were 22.2%and 98.7%,respectively.In both groups,the mean maximum dimension of the concurrent cancers identified in the CT-negative cases was shorter than in the CT-positive cases(incomplete group:P=0.02;complete group:P<0.01)Topographical proximity to synchronous cancers was identified as a risk factor for missed diagnosis(P=0.03).CONCLUSION:CT has limited sensitivity in detecting SCRCs in patients receiving incomplete colonoscopy.Patients with risk factors and negative CT results should be closely examined and monitored.     

Effect of diet on fecal occult blood testing in patients with colorectal polyps

To determine the effect of a red-meat-free, high-fiber diet, patients performed fecal blood testing before colonoscopy for suspected polyps. One hundred twenty-nine patients were allowed an unrestricted diet, and 159 consumed the special diet. Without dietary restrictions, 31 of 77 patients with adenomas, five of eight with cancer, one of seven with nonneoplastic polyps, and one of 37 with normal colonoscopy had positive tests. With the special diet, 30 of 97 patients with adenomas, eight of ten with cancer, one of six with nonneoplastic polyps, and one of 46 with normal colonoscopy had positive tests. There are no statistical differences between the groups. Comparing all patients with cancer to those with normal colonoscopy, the sensitivity of fecal blood testing is 72%, the specificity 98%, and the positive and negative predictive value 87% and 94%, respectively. The sensitivity for fecal blood testing in patients with adenomas (compared to those with normal endoscopy) is 35%, the specificity is 98%, and the positive and negative predictive values are 97% and 42%, respectively. Combining all patients with adenomas, those with multiple polyps, larger polyps, or polyps located distal to the splenic flexure had positive fecal blood tests more frequently. Fecal blood testing does not detect a large number of colorectal adenomas. This study does not indicate any benefit on the sensitivity or specificity of fecal blood tests from the red-meat-free, high-fiber diet currently recommended.     

Role of computed tomographic colonoscopy of postoperative surveillance in patient with gastric cancer

AIM: To examine the diagnostic yield of colorectal neoplasia at computed tomographic colonoscopy (CTC) as well as the feasibility of contrast enhanced CTC in patients with gastric cancer. METHODS: To examine the incidence of colon polyp we selected postoperative 188 gastric cancer patients, which we refer to as the 'colon polyp survey group'. To examine the feasibility of CTC for early detection of colon cancer or advanced colon adenoma, we selected 47 gastric cancer patients (M:F 29:18, mean age 53.8 years), which we call the 'CT colonoscopy group'. All the 47 patients underwent successive CTC and colonoscopy on the same day. RESULTS: Totally 109 colon polyps were observed from 59 out of 188 gastric cancer patients, the incidence rate of colon polyps in gastric cancer patients being 31.4%. The sensitivity of CTC in detecting individuals with at least 1 lesion of any size was 57.1%, the specificity was 72.7%, the positive predictive value was 47.1%, and the negative predictive value was 71.9%. When the cutoff size was decreased to 6 mm, the sensitivity and specificity were 80.0% and 92.9%, respectively, with positive and negative predictive values of 57.1% and 97.5%, respectively. Only one patient was classified as false negative by virtual colonoscopy. CONCLUSION: The diagnostic yield of colorectal polyp was 31.4% in patients with gastric cancer, and contrast enhanced CTC is an acceptable tool for the detection of synchronous colorectal advanced adenoma andpostoperative surveillance of gastric cancer patients.     

Colorectal cancer screening, comorbidity, and follow-up in elderly patients

OBJECTIVE: We examined the relationship between comorbid disease and performance of complete colon examination by colonoscopy or double contrast barium enema (DCBE) after positive screening fecal occult blood test (FOBT) in patients 70 years of age or older. BACKGROUND: FOBT is an accepted form of colorectal cancer (CRC) screening. Factors that influence follow-up of positive FOBT have been largely unknown. METHODS: Patients aged 70 years and older with positive FOBT between March 1, 2000 and Feb 28, 2001 were included in this retrospective medical record review performed at a single center. Comorbidity was measured by the Charlson Comorbidity Scale. RESULTS:: In our sample of 266 subjects, 193 (73%) were referred for evaluation of positive FOBT and 109 (41%) underwent a colonoscopy or DCBE within 12 months. Using the Charlson score for comorbidity, 27% of our sample scored 0, 24% scored 1, and 23% scored 2 while 26% had a Charlson score of 3 or higher. There was no association between Charlson score (0, 1, 2, and > or =3) and referral for evaluation (chi test, P = 0.28) or performance of a complete colon examination (chi test, P = 0.38). CONCLUSIONS: In this sample, only 41% of patients with positive FOBT underwent a full colon examination within 12 months of a positive FOBT. Although comorbidity burden was considerable, there was no association between comorbidity score and referral for or performance of a full colon examination. These results suggest that inappropriate patients receive CRC screening, which may contribute to delays for screening appropriate patients and diagnostic delays for others with positive screening test findings.     

Screening of patients with acute infectious diarrhoea: evaluation of clinical features, faecal microscopy, and faecal occult blood testing

BACKGROUND: For optimal management of acute infectious diarrhoeal diseases, it is necessary to utilize a screening process to distinguish between invasive and non-invasive diarrhoeas. The aim of this study was to compare the diagnostic utilities of clinical features, faecal microscopy (FM), and faecal occult blood testing (FOBT) in distinguishing invasive diarrhoeas from non-invasive ones. METHODS: A total of 1008 patients with acute diarrhoea were evaluated. Rectal swabs were cultured for Salmonella, Shigella, and Vibrio species; rectal swabs from 109 of these patients were also examined for Campylobacter, enterotoxigenic Escherichia coli, and rotavirus species. Isolation of faecal enteropathogens served as the gold standard. FOBT was performed with a commercial modified guaiac test. Specificity, sensitivity, positive predictive value (PPV), negative predictive value (NPV), accuracy, and likelihood ratio were compared. RESULTS: Among the 1008 patients 402 with a single identified enteropathogen were available for analysis. Invasive and non-invasive enteropathogens were isolated from 262 (65.2%) and 140 (34.8%) cases, respectively. The presence of visible blood in faeces was almost a pathognomonic sign of invasive diarrhoea but had poor sensitivity. Clinical features were useful but inadequate in differentiating patients with non-bloody diarrhoea (74% of patients) into invasive and non-invasive categories. The sensitivities, specificities, PPVs, and NPVs of FM and FOBT were 75%, 77%, 58%, 88%, and 85%, 68%, 53%, and 91%, respectively. CONCLUSION: The presence of visible blood in faeces is a highly specific clinical feature of invasive diarrhoea but suffers from low sensitivity. In non-bloody diarrhoea FOBT is a valuable screening test and is comparable to FM, particularly when interpreted in the clinical context.     

Screening of Patients with Acute Infectious Diarrhoea: Evaluation of Clinical Features,Faecal Microscopy,and Faecal Occult Blood Testing

Background: For optimal management of acute infectious diarrhoeal diseases, it is necessary to utilize a screening process to distinguish between invasive and non-invasive diarrhoeas. The aim of this study was to compare the diagnostic utilities of clinical features, faecal microscopy (FM), and faecal occult blood testing (FOBT) in distinguishing invasive diarrhoeas from non-invasive ones. Methods: A total of 1008 patients with acute diarrhoea were evaluated. Rectal swabs were cultured for Salmonella, Shigella, and Vibrio species; rectal swabs from 109 of these patients were also examined for Campylobacter, enterotoxigenic Escherichia coli, and rotavirus species. Isolation of faecal enteropathogens served as the gold standard. FOBT was performed with a commercial modified guaiac test. Specificity, sensitivity, positive predictive value (PPV), negative predictive value (NPV), accuracy, and likelihood ratio were compared. Results: Among the 1008 patients 402 with a single identified enteropathogen were available for analysis. Invasive and non-invasive enteropathogens were isolated from 262 (65.2%) and 140 (34.8%) cases, respectively. The presence of visible blood in faeces was almost a pathognomonic sign of invasive diarrhoea but had poor sensitivity. Clinical features were useful but inadequate in differentiating patients with non-bloody diarrhoea (74% of patients) into invasive and non-invasive categories. The sensitivities, specificities, PPVs, and NPVs of FM and FOBT were 75%, 77%, 58%, 88%, and 85%, 68%, 53%, and 91%, respectively. Conclusion: The presence of visible blood in faeces is a highly specific clinical feature of invasive diarrhoea but suffers from low sensitivity. In non-bloody diarrhoea FOBT is a valuable screening test and is comparable to FM, particularly when interpreted in the clinical context.     

Physician-reported reasons for limited follow-up of patients with a positive fecal occult blood test screening result

OBJECTIVE: Fecal occult blood testing (FOBT) screening can reduce colorectal cancer (CRC) mortality when patients with an abnormal result [FOBT(+)] undergo a complete diagnostic evaluation (colonoscopy or double-contrast barium enema with or without flexible sigmoidoscopy). The aim of this study was to determine common reasons for nonperformance of a complete diagnostic evaluation. METHODS: We identified 544 FOBT(+) patients, aged 50 yr or older, who had participated in a managed care organization-sponsored CRC screening program. The performance of a complete diagnostic evaluation was determined from a patient-specific follow-up form and managed care organization claims data. Physicians were asked to report whether patients submitted to a complete diagnostic evaluation. When an evaluation was not done, the physicians were also asked to state the reasons for nonperformance. RESULTS: A total of 248 (46%) patients did not undergo a complete diagnostic evaluation. Physicians provided reasons for nonperformance for 50% (123/248). Factors accounting for nonperformance of a complete diagnostic evaluation were classified as follows: primary care physician decision (50%); specialist decision (28%); patient decision (17%); and other (practice-related) (5%). Many failures to complete an appropriate diagnostic evaluation were due to providers deciding to repeat the FOBT, perform a sigmoidoscopy, or not to proceed with any further testing. CONCLUSION: Many patients with a positive FOBT do not receive a complete diagnostic evaluation. The reasons for nonperformance most frequently have to do with physician decision making. Many physician-related explanations do not conform to expert recommendations for appropriate follow-up.