Guaiac-based Fecal Occult Blood Test Research Articles

Optimising faecal occult blood screening:retrospective analysis of NHS Bowel Cancer Screening data to improve the screening algorithm.

Background:Colorectal neoplasia causes bleeding, enabling detection using Faecal Occult Blood tests (FOBt). The National Health Service (NHS) Bowel Cancer Screening Programme (BCSP) guaiac-based FOBt (gFOBt) kits contain six sample windows (or ‘spots') and each kit returns either a positive, unclear or negative result. Test kits with five or six positive windows are termed ‘abnormal' and the subject is referred for further investigation, usually colonoscopy. If 1–4 windows are positive, the result is initially ‘unclear' and up to two further kits are submitted, further positivity leads to colonoscopy (‘weak positive'). If no further blood is detected, the test is deemed ‘normal' and subjects are tested again in 2 years' time. We studied the association between spot positivity % (SP%) and neoplasia.Methods:Subjects in the Southern Hub completing the first of two consecutive episodes between April 2009 and March 2011 were studied. Each episode included up to three kits and a maximum of 18 windows (spots). For each positivity combination, the percentage of positive spots out of the total number of spots completed by an individual in a single-screening episode was derived and named ‘SP%'. Fifty-five combinations of SP can occur if the position of positive/negative spots on the same test card is ignored.The proportion of individuals for whom neoplasia was identified in Episode 2 was derived for each of the 55 spot combinations. In addition, the Episode 1 spot pattern was analysed for subjects with cancer detected in Episode 2.Results:During Episode 2, 284 261 subjects completed gFOBT screening and colonoscopies were performed on 3891 (1.4%) subjects. At colonoscopy, cancer was detected in 7.4% (n=286) and a further 39.8% (n=1550) had adenomas. Cancer was detected in 21.3% of subjects with an abnormal first kit (five or six positive spots) and in 5.9% of those with a weak positive test result.The proportion of cancers detected was positively correlated with SP%, with an R2 correlation (linear) of 0.89. As the SP% increased from 11 to 100%, so the colorectal cancer (CRC) detection rate increased from 4 to 25%. At the lower SP%s, from 11to 25%, the CRC risk was relatively static at ∼4%. Above an SP% of 25%, every 10-percentage points increase in the SP%, was associated with an increase in cancer detection of 2.5%.Conclusions:This study demonstrated a strong correlation between SP% and cancer detection within the NHS BCSP. At the population level, subjects' cancer risk ranged from 4 to 25% and correlated with the gFOBt spot pattern.Some subjects with an SP% of 11% proceed to colonoscopy, whereas others with an SP% of 22% do not. Colonoscopy on patients with four positive spots in kit 1 (SP% 22%) would, we estimate, detect cancer in ∼4% of cases and increase overall colonoscopy volume by 6%. This study also demonstrated how screening programme data could be used to guide its ongoing implementation and inform other programmes.

Long-term effect of faecal occult blood screening on incidence and mortality from colorectal cancer

BackgroundSeveral randomized trials have shown a reduction of colorectal cancer mortality by screening using guaiac-based faecal occult blood tests. However, little is known on the long-term effect of screening at the population level in everyday practice. MethodsSmall-sized geographic areas including a total of 91,199 individuals were allocated to either biennal screening using the Hemoccult-II test or no screening. The expected mortality and incidence in the cohort invited to screening was determined using mortality and incidence in the non-screened population. ResultsColorectal cancer mortality was significantly lower in the population invited to screening than in the non-screened population after 11 screening rounds (standardized mortality ratio: 0.87; 0.80–0.94). The standardized mortality ratio remained significant whatever the duration of follow-up. This reduction in colorectal cancer mortality was more pronounced in those who participated in the first screening campaign, who were regular participants in screening rounds (standardized mortality ratio: 0.67; 0.59–0.76). In contrast, colorectal cancer incidence was not different between the screened and non-screened populations (standardized incidence ratio: 1.01; 0.96–1.06). ConclusionOur findings confirm, in the long term, that screening with Hemoccult can reduce colorectal cancer mortality. The data also highlight the benefit of regular participation in screening and the absence of effect of screening on colorectal cancer incidence.

Which adenomas are detected by fecal occult blood testing? A state-wide analysis from Bavaria, Germany.

Guaiac-based fecal occult blood tests (gFOBTs) are the most widely used noninvasive tests for colorectal cancer screening. While it is well known that they detect only a minority of colorectal adenomas, evidence for the characteristics of adenomas associated with detection is sparse. We derived estimates of the positive likelihood ratio (LR+), a summary measure of diagnostic performance, according to adenoma characteristics by comparing findings at colonoscopy among 19,208 and 181,128 participants who underwent colonoscopy to follow-up a positive gFOBT and as a primary screening examination, respectively, in Bavaria, Germany, in 2007-2009. Age and sex-adjusted estimates of LR+ (95% confidence intervals, 95% CI) ranged from 1.09 (1.05-1.13) for adenomas <1 cm to 2.52 (2.30-2.75) for adenomas >2 cm, and were much higher for pedunculated adenomas (1.96, 95% CI 1.85-2.08) than for flat or sessile adenomas (1.11, 95% CI 1.02-1.21 and 1.12, 95% CI 1.08-1.16, respectively). Villous or tubulovillous structure and dysplasia were likewise associated with a higher chance to be detected by gFOBT. Diagnostic performance was worse for proximal than for distal adenomas (age and sex adjusted LR+:1.16, 95% CI 1.09-1.23 and 1.35, 95% CI 1.29-1.41, respectively) which was explained by the lower proportions of large, pedunculated and nontubular adenomas in the proximal colon. Size, pedunculated shape, and nontubular histology are the key determinants of detection which also explain lower detection rates of adenomas located in the proximal colon.

Systematic review and bivariate/HSROC random-effect meta-analysis of immunochemical and guaiac-based fecal occult blood tests for colorectal cancer screening.

Current literature evidences higher accuracy of immunological (iFOBT) vis-à-vis guaiac-based (gFOBT) fecal occult blood tests for colorectal cancer (CRC) screening. Few well-designed head-to-head comparisons exist. This meta-analysis assesses the performances of two iFOBTs compared with an established gFOBT using colonoscopy as the gold standard. We mobilized a bivariate and a hierarchical summary receiver operating characteristic (HSROC) model. Positive likelihood ratio (LR) and negative likelihood ratio (LR) and diagnostic odds ratios were back-calculated. We constructed bivariate credibility ellipses in the HSROC space and calculated areas under the curve to obtain a global measure of test performance. Estimates are presented at 95% credibility levels. We included and analyzed 21 studies. OC-Sensor was the best test for CRC screening, with high sensitivity (0.87; 95% credibility interval: 0.73-0.95) and specificity (0.93; 95% credibility interval: 0.84-0.96), optimal LR (12.01) and LR (0.14), and a high diagnostic odds ratio (88.05). Bivariate credibility ellipses showed OC-Sensor's dominance over Hemoccult (sensitivity: 0.47; 95% credibility interval: 0.37-0.58; specificity: 0.93; 95% credibility interval: 0.91-0.95). Our findings support the use of OC-Sensor for CRC detection. The diagnostic estimates obtained may be extended to derive model parameters for economic decision models and to offer insight for future clinical and public health decision making. Our findings could influence the future of FOBTs within the CRC screening arsenal.

A Fourth Randomized, Controlled Trial of Flexible Sigmoidoscopy Screening

Three previous trials from the U.K., Italy, and the U.S. have demonstrated that flexible sigmoidoscopy reduces distal colorectal cancer (CRC) incidence and mortality. In a fourth trial from Norway, 98,792 asymptomatic persons were randomized to receive no screening (78,220), flexible sigmoidoscopy (10,283), or flexible sigmoidoscopy plus guaiac-based fecal occult blood test (FOBT; 10,289). Adherence was higher in the flexible-sigmoidoscopy-only group compared with the flexible-sigmoidoscopy-plus-FOBT group (65.1% vs. 60.9%; P <0.001). Based on intention to screen, CRC incidence was reduced by 20% overall, 32% in the 50-to-54-year age …

Cost-effectiveness of colorectal cancer screening in Germany: current endoscopic and fecal testing strategies versus plasma methylated Septin 9 DNA.

Background and study aims: Colorectal cancer (CRC) screening strategies in Germany include guaiac-based fecal occult blood testing (gFOBT) starting at age 50 and a switch to colonoscopy at age 55 or continued gFOBT testing, but screening utilization is limited. Blood-based biomarkers, such as methylated Septin 9 DNA (mSEPT9), may improve screening rates. We performed a cost-effectiveness analysis of current and emerging CRC screening strategies in Germany. Methods: Using a validated Markov model, we compared annual gFOBT for ages 50 through 54 followed by biennial testing until age 75 (FOBT) or by colonoscopy at ages 55 and 65 (FOBT/COLO 55,65), substitution of fecal immunochemical testing (FIT) for gFOBT (FIT, FIT/COLO 55,65), and annual or biennial plasma mSEPT9 testing. We also considered persons who utilize only colonoscopy and varied age at colonoscopy utilization. Results: The current strategies were more effective and less costly than no screening. FIT was more effective and less costly than mSEPT9 testing. FIT/COLO 55,65 cost €12 200 per quality-adjusted life-years gained in comparison with FIT. mSEPT9-based screening was cost-effective in comparison with no screening but was dominated by other cost-saving strategies. Differential screening utilization and adherence greatly affected incremental results between strategies. In probabilistic analyses, FIT was preferred in 49 % and FIT/COLO 55,65 in 47 % of iterations. Conclusion: Currently available CRC screening strategies in Germany, including hybrid fecal testing/colonoscopy, are likely to be cost-saving. Current strategies appear superior to mSEPT9-based screening. The impact of blood-based biomarkers is likely to depend on utilization and adherence as much as on test performance characteristics and cost.

PWE-019 An Evaluation Of Quantitative Faecal Immunochemical Tests For Haemoglobin

IntroductionThe NHS Bowel Cancer Screening Programme (BCSP) in England provides biennial screening using a guaiac-based faecal occult blood test (gFOBT) for people aged 60–74 years. The European guidelines1 recommend use...

Colorectal cancer screening uptake over three biennial invitation rounds in the English bowel cancer screening programme

ObjectiveTo examine patterns of colorectal cancer (CRC) screening uptake over three biennial invitation rounds in the National Health Service (NHS) Bowel Cancer Screening Programme (BCSP) in England.MethodsWe analysed data from...

Tests and investigations for colorectal cancer screening

Worldwide, colorectal (CRC) is the third most common form of cancer, after lung and breast cancer, and the fourth most common cause of cancer death, although in developed countries CRC incidence is higher and it accounts for an even higher proportion of cancer deaths. Successful treatment of early-stage CRC confers substantial survival advantage, and there is now overwhelming evidence that screening average-risk individuals for CRC reduces the incidence and disease-specific mortality. In spite of considerable research for new biomarkers for CRC, the detection of blood in faeces remains the most effective screening tool. The best evidence to date for population-based CRC screening comes from randomised-controlled trials that used a guaiac-based faecal occult blood test (gFOBt) as the first-line screening modality, whereby test-positive individuals are referred for follow-up investigations, usually colonoscopy. A major innovation in the last ten years or so has been the development of other more analytically sensitive and specific screening techniques for blood in faeces. The faecal immunochemical test for haemoglobin (FIT) confers substantial benefits over gFOBt in terms of analytical sensitivity, specificity and practicality and FIT are now recommended for CRC screening by the European guidelines for quality assurance in colorectal cancer screening and diagnosis. The challenge internationally is to develop high quality CRC screening programmes for which uptake is high. This is especially important for developing countries witnessing an increase in the incidence of CRC as populations adopt more westernised lifestyles.This review describes the tests available for CRC screening and how they are being used worldwide. The reader will gain an understanding of developments in CRC screening and issues that arise in choosing the most appropriate screening test (or tests) for organised population-based screening internationally and optimising the performance of the chosen test (or tests). Whilst a wide range of literature has been cited, this is not a systematic review. The authors provide FOBT CRC screening for a population of 14.6 million in the south of England and the senior author (SPH) was the lead author of the European guidelines for quality assurance in colorectal cancer screening and diagnosis and leads the World Endoscopy Organization Colorectal Cancer Committee’s Expert Working Group on ‘FIT for Screening’.

Comparison of Fecal Occult Blood Tests for Colorectal Cancer Screening in an Alaska Native Population With High Prevalence ofHelicobacter pyloriInfection, 2008–2012

IntroductionAlaska Native colorectal cancer (CRC) incidence and mortality rates are the highest of any ethnic/racial group in the United States. CRC screening using guaiac-based fecal occult blood tests (gFOBT) are not recommended for Alaska Native people because of false-positive results associated with a high prevalence of Helicobacter pylori-associated hemorrhagic gastritis. This study evaluated whether the newer immunochemical FOBT (iFOBT) resulted in a lower false-positive rate and higher specificity for detecting advanced colorectal neoplasia than gFOBT in a population with elevated prevalence of H. pylori infection.MethodsWe used a population-based sample of 304 asymptomatic Alaska Native adults aged 40 years or older undergoing screening or surveillance colonoscopy (April 2008–January 2012).ResultsSpecificity differed significantly (P < .001) between gFOBT (76%; 95% CI, 71%–81%) and iFOBT (92%; 95% CI, 89%–96%). Among H. pylori-positive participants (54%), specificity of iFOBT was even higher (93% vs 69%). Overall, sensitivity did not differ significantly (P = .73) between gFOBT (29%) and iFOBT (36%). Positive predictive value was 11% for gFOBT and 32% for iFOBT.ConclusionThe iFOBT had a significantly higher specificity than gFOBT, especially in participants with current H. pylori infection. The iFOBT represents a potential strategy for expanding CRC screening among Alaska Native and other populations with elevated prevalence of H. pylori, especially where access to screening endoscopy is limited.

An updated Asia Pacific Consensus Recommendations on colorectal cancer screening

ObjectiveSince the publication of the first Asia Pacific Consensus on Colorectal Cancer (CRC) in 2008, there are substantial advancements in the science and experience of implementing CRC screening. The Asia...

Ontario's ColonCancerCheck: Results from Canada's First Province-Wide Colorectal Cancer Screening Program

ColonCancerCheck (CCC), Canada's first province-wide colorectal cancer screening program, was publicly launched in Ontario in April 2008. The objective of this article is to report on key indicators of CCC Program performance since its inception. The CCC Program recommends biennial guaiac-based fecal occult blood test (gFOBT) for persons 50 to 74 years of age at average risk for colorectal cancer and colonoscopy for those at increased risk (having one or more first-degree relatives with a diagnosis of colorectal cancer). Opportunistic screening with colonoscopy is available in Ontario. Five data sources were used to compute indicators of program performance during 2008 to 2011. The indicators computed were FOBT participation, overdue for screening, FOBT positivity, positive predictive value (PPV) of FOBT for colorectal cancer, diagnostic follow-up, and colorectal cancer detection rate. In 2011, FOBT participation was 29.8% and 46.8% of the target population was overdue for screening. FOBT positivity was higher among men (5.1%) than women (3.5%), and the PPV of FOBT for cancer was 4.3% in 2011. Follow-up colonoscopy within 6 months of a positive FOBT was completed by 74.6% of Program participants in 2011. The cancer detection rates for FOBT and for colonoscopy in those with a family history were 1.3 per 1,000 and 4.0 per 1,000, respectively, in 2011. These results provide an early indication of Program performance and provide findings relevant to other organized colorectal cancer screening programs. The greater cancer detection rate in those at increased risk due to family history who undergo colonoscopy screening suggests that a strategy of risk stratification will enhance the impact of FOBT-based screening programs.

Guaiac-Based Fecal Occult Blood Screening Performs Poorly

Guaiac-based fecal occult blood test (gFOBT) screening for colorectal cancer (CRC) has been proven in randomized trials to reduce CRC mortality.

Evaluation of Plasma microRNA Expression Levels in Early Diagnosis of Colorectal Cancer

Evaluation of Plasma microRNA Expression Levels in Early Diagnosis of Colorectal Cancer Background: Colorectal cancer (CRC) is the third most frequently diagnosed cancer all over the world and the prognosis is associated with the stage at diagnosis. Due to insufficient sensitivity of tumor markers, as CEA, CA19.9, guaiac-based fecal occult blood and fecal immunochemical occult blood testing used in the routine, there is a need for non-invasive, new biomarkers with high sensitivity and specificity and they will be helpful in early diagnosis. microRNAs (miRNA) are small, single-stranded noncoding transcripts, and some of them play critical roles in tumorigenesis and have a potentially clinical value in diagnosis, treatment and prognosis evaluation for CRC. In this study we aimed to compare miRNA’s expression profiles between pathologically diagnosed CRC patients and healthy control groups. Methods: Blood samples from participants were collected for test-scale analysis. Plasma samples were extracted from whole blood, then total RNA are isolated and pre-amplified as manufacturer’s protocol. Finally, real-time PCR step was performed with BioMark System by using manufacturer’s protocol. Results: Plasma samples of 37 CRC patients and 238 healthy subjects were examined to profiling 741 miRNAs expression, using high-throughput real-time quantitative RT-PCR. Among them, 3 miRNAs (miR-1274A, miR- 875-5p, miR-34c-5p) were found significantly up-regulated while 8 miRNAs (miR-30d-5p, miR-150-5p, miR-30a-5p, miR-34a-5p, miR-223-3p, miR-576- 3p, miR-30c-5p, miR-195-5p) were found down-regulated in CRC patients compared to control group. Conclusion: In this study it was shown that miR-150-5p, miR-30a-5p, miR- 34a-5p, and miR-195-5p can be helpful in early diagnosis of CRC similar to some other studies.

Diagnostic Performance of Guaiac-Based Fecal Occult Blood Test in Routine Screening: State-Wide Analysis from Bavaria, Germany

Randomized trials have shown that annual or biannual screening by guaiac-based fecal occult blood tests (gFOBTs) reduces colorectal cancer (CRC) mortality. Few clinical studies have evaluated diagnostic performance of gFOBT through validation by colonoscopy in all participants. We aimed for a comprehensive evaluation of diagnostic performance of gFOBT by age and sex under routine screening conditions. Our analysis is based on 20,884 colonoscopies following up a positive gFOBT and 182,956 primary screening colonoscopies documented in a state-wide quality assurance program in Bavaria, Germany, in 2007-2009. Positive likelihood ratios (LR+), which represent an integrative measure of diagnostic performance, were derived, by age groups (55-59, 60-64, 65-69, 70-74 years) and sex, from a joint and comparative analysis of prevalences of colorectal neoplasms in both groups. Overall LR+ (95% confidence intervals) were 1.11 (1.06-1.15), 1.80 (1.72-1.88), and 5.04 (4.64-5.47) for non-advanced adenoma, advanced adenoma, and cancer, respectively. Assuming a specificity of gFOBT of 95.2%, as recently observed in a German study among 2,235 participants of screening colonoscopy, these LR+ would translate to sensitivities of 5.3%, 8.6%, and 24.2% for the three outcomes, respectively. Diagnostic performance was similarly poor among women and men and across age groups. The performance of gFOBT under routine screening conditions is even worse than previously estimated from clinical studies. In routine screening application, gFOBTs are expected to miss more than 9 out of 10 advanced adenomas and 3 out of 4 cancers. These results underline the need and the potential for better noninvasive CRC screening tests.

Men with negative results of guaiac‐based fecal occult blood test have higher prevalences of colorectal neoplasms than women with positive results

Guaiac-based fecal occult blood tests (gFOBTs) are the most commonly applied tests for colorectal cancer screening globally but have relatively poor sensitivity to detect colorectal neoplasms. Men have higher prevalences of colorectal neoplasms than women. In case of a positive gFOBT result, participants are referred to colonoscopy, independent of sex. To assess performance of gFOBT in routine screening practice, we assessed age and sex specific prevalences (age groups: 55-59, 60-64, 65-69 and 70-74) of colorectal neoplasms in 182,956 women and men undergoing colonoscopy for primary screening and in 20,884 women and men undergoing colonoscopy to follow-up a positive gFOBT in Bavaria, Germany, in 2007-2009. We conducted model calculations to estimate prevalences among gFOBT negative individuals. Analogous model calculations were performed for women and men tested positive or negative with fecal immunochemical tests. In all age groups (55-59, 60-64, 65-69 and 70-74 years), men undergoing colonoscopy for primary screening had substantially higher prevalences of any colorectal neoplasms and essentially the same prevalences of advanced colorectal neoplasms compared to women undergoing colonoscopy to follow-up a positive gFOBT. Model calculations suggest that men with negative gFOBT likewise have substantially higher prevalences of colorectal neoplasms than gFOBT positive women in each age group. Model calculations further indicate that no such sex paradoxon occurs, and a much clearer risk stratification can be achieved with fecal immunochemical tests. Our findings underline need to move forward from and overcome shortcomings of gFOBT-based colorectal cancer screening.

Is family history alone a sufficient indicator for screening colonoscopy?

483 ISSN 1758-194X 10.2217/CRC.13.67 © 2013 Future Medicine Ltd Colorect. Cancer (2013) 2(6), 483–485 1Department of Radiation Oncology, Princess Margaret Cancer Centre, 610 University Avenue, Toronto, Ontario, M5G 2M9, Canada, *Author for correspondence: rebecca.wong@rmp.uhn.on.ca Colorectal cancer (CRC) represents one of the few cancers where screening and early diagnosis is possible and mortality preventable. Since the first appearance of evidence in support of the potential for screening to reduce morbidity and mortality due to CRC 20 years ago, many practice guidelines have been written, and in many cases, serve as blue prints for establishing screening programs and compliance, used as standard for measuring quality of cancer care at a population level. In the USA and Canada, the guidelines maintained by the US Prevention Task Force [1] and the US Multi-Society Task Force [2] have served as key guidance documents, while similar guidelines are available in other jurisdictions [3,4]. These guidelines share the common theme of classifying patients into average, increased and high-risk categories where family history plays a major role in risk categorization. Different screening strategies have been recommended for different risk groups. For example, the US Multi-Society Task Force recommended colonoscopy (10-yearly), flexible sigmoidoscopy, barium enema, computed tomography (5-yearly), guaiac-based fecal occult blood test, fecal immunochemical test or stool DNA test (annually) as suitable screening strategies for ‘average-risk’ individuals. For those with ‘increased risk’ (a family history of one or more first-degree relatives with CRC), colonoscopy every 5 years commencing 10 years before the youngest case was recommended. Patients who fall under the high risk category include those with Lynch syndrome, familial adenomatous polyposis and inflammatory bowel disease. Individuals confirmed to have Lynch syndrome are recommended to undergo screening colonoscopy every 2 years beginning between the age of 20 to 25 years [5]. Separate guidelines including family history characteristics have been created to guide case identification [5,6]. Family history is the most powerful predictive factor for ascertaining CRC risk, supplemented by age, sex, smoking, excess body “Ultimately, the effectiveness of a particular screening strategy for a specific risk group rests with the impact it has on the incidence and mortality of colorectal cancer.” EDITORIAL

Accuracy of faecal occult blood test and Helicobacter pylori stool antigen test for detection of upper gastrointestinal lesions

ObjectiveHighly sensitive guaiac-based faecal occult blood (Hemoccult SENSA) and Helicobacter pylori stool antigen testing might help detect upper gastrointestinal lesions when appended to a colorectal cancer screening programme with faecal...

Flexible sigmoidoscopy versus faecal occult blood testing for colorectal cancer screening in asymptomatic individuals

Colorectal cancer is the third most frequent cancer in the world. As the sojourn time for this cancer is several years and a good prognosis is associated with early stage diagnosis, screening has been implemented in a number of countries. Both screening with faecal occult blood test and flexible sigmoidoscopy have been shown to reduce mortality from colorectal cancer in randomised controlled trials. The comparative effectiveness of these tests on colorectal cancer mortality has, however, never been evaluated, and controversies exist over which test to choose. To compare the effectiveness of screening for colorectal cancer with flexible sigmoidoscopy to faecal occult blood testing. We searched MEDLINE and EMBASE (November 16, 2012), the Cochrane Central Register of Controlled Trials (CENTRAL) (2012, Issue 11) and reference lists for eligible studies. Randomised controlled trials comparing screening with flexible sigmoidoscopy or faecal occult blood testing to each other or to no screening. Only studies reporting mortality from colorectal cancer were included. Faecal occult blood testing had to be repeated (annually or biennially). Data retrieval and assessment of risk of bias were performed independently by two review authors. Standard meta-analyses using a random-effects model were conducted for flexible sigmoidoscopy and faecal occult blood testing (FOBT) separately and we calculated relative risks with 95% confidence intervals (CI). We used a Bayesian approach (a contrast-based network meta-analysis method) for indirect analyses and presented the results as posterior median relative risk with 95% credibility intervals. We assessed the quality of evidence using GRADE. We identified nine studies comprising 338,467 individuals randomised to screening and 405,919 individuals to the control groups. Five studies compared flexible sigmoidoscopy to no screening and four studies compared repetitive guaiac-based FOBT (annually and biennially) to no screening. We did not consider that study risk of bias reduced our confidence in our results. We did not identify any studies comparing the two screening methods directly. When compared with no screening, colorectal cancer mortality was lower with flexible sigmoidoscopy (relative risk 0.72; 95% CI 0.65 to 0.79, high quality evidence) and FOBT (relative risk 0.86; 95% CI 0.80 to 0.92, high quality evidence). In the analyses based on indirect comparison of the two screening methods, the relative risk of dying from colorectal cancer was 0.85 (95% credibility interval 0.72 to 1.01, low quality evidence) for flexible sigmoidoscopy screening compared to FOBT. No complications occurred after the FOBT test itself, but 0.03% of participants suffered a major complication after follow-up. Among more than 60,000 flexible sigmoidoscopy screening procedures and almost 6000 work-up colonoscopies, a major complication was recorded in 0.08% of participants. Adverse event data should be interpreted with caution as the reporting of adverse effects was incomplete. There is high quality evidence that both flexible sigmoidoscopy and faecal occult blood testing reduce colorectal cancer mortality when applied as screening tools. There is low quality indirect evidence that screening with either approach reduces colorectal cancer deaths more than the other. Major complications associated with screening require validation from studies with more complete reporting of harms

Limited Clinical Utility of the Fecal Occult Blood Test for Evaluation of Gastrointestinal Bleed in Hospitalized Patients

Purpose: Fecal occult blood test (FOBT) is widely used for colorectal cancer screening in an outpatient setting. There is little data on whether an inpatient FOBT will guide clinical management. This is a study evaluating the clinical effectiveness of an inpatient FOBT to predict significant endoscopic lesions in the setting of a gastrointestinal (GI) bleed. Methods: We reviewed laboratory and endoscopic reports from hospitalized patients with FOBT performed over one year at a single university-based medical center. Statistical analysis was performed using the Chi Square test and multivariate regression analysis to determine whether the use of inpatient FOBT can predict significant endoscopic lesions. Results: A total of 575 anemic patients were checked for a guaiac-based FOBT during admission. Patient characteristics included ages 19-94 years (mean 58), 327 men, and 248 women. A total of 167 GI consults were placed and 119 patients underwent 182 endoscopies (89 EGD, 63 colonoscopy, and 30 flexible sigmoidoscopy). Among 67 overt GI bleeding patients, 79% were found to have positive endoscopic findings predominantly with high risk stigmata. Of those with positive endoscopic findings, 60.5% were FOBT positive and 41.5% were FOBT negative, clinically non-significant between the two groups (p=0.52). Among 52 suspected occult GI bleeding patients, FOBT and iron deficiency anemia status were not significantly different in predicting a clinically significant endoscopic lesion. On multivariate regression analysis, the strongest predictor for an endoscopic lesion was the presence of a low hemoglobin (OR 1.67; 95% CI 1.08-2.56; p<0.05). On the other hand, a positive FOBT correlated with an 80% probability of less positive endoscopic lesions (OR 0.20; 95% CI 0.04-0.95; p<0.05). Regardless of the FOBT status, the presence of GI symptoms coupled with abnormal imaging has a high predictive value of 64% for clinically significant endoscopic lesions. Conclusion: In our study, there is limited utility of checking FOBT in the inpatient setting. It is potentially harmful in a clinically overt GI bleeding patient. Thus, inpatient FOBT should not be checked in an overt GI bleeding patient with the potential for false negatives which may delay endoscopic intervention. Limitations of checking an inpatient FOBT in a suspected occult GI bleeding patient stem from high rates of false positives due to lack of strict dietary and medication adherence. Nonetheless, gastrointestinal symptoms coupled with an abnormal imaging and severe anemia is the most important predictor of a clinically significant endoscopic finding. Future prospective and randomized controlled trials are needed to determine if there is any role for FOBT in an inpatient setting.