***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: Objective Colorectal cancer screening programmes are implemented worldwide ; many are based on faecal immunochemical testing ( FIT ) . The aim of this study was to evaluate two frequently used FITs on participation , usability , positivity rate and diagnostic yield in population -based FIT screening . Design Comparison of two FITs was performed in a fourth round population -based FIT-screening cohort . R and omly selected individuals aged 50–74 were invited for FIT screening  and were r and omly allocated to receive an OC -Sensor ( Eiken , Japan ) or faecal occult blood (FOB)-Gold ( Sentinel , Italy ) test ( March – December 2014 ) . A cut-off of 10 µg haemoglobin (Hb)/g faeces ( ie , 50 ng Hb/mL buffer for OC-Sensor and 59 ng Hb for FOB-Gold ) was used for both FITs . Results In total , 19 291 eligible invitees were included ( median age 61 , IQR 57–67 ; 48 % males ) : 9669 invitees received OC-Sensor and 9622 FOB-Gold ; both tests were returned by 63 % of invitees ( p=0.96 ) . Tests were non-analysable in 0.7 % of participants using OC-Sensor vs 2.0 % using FOB-Gold ( p<0.001 ) . Positivity rate was 7.9 % for OC-Sensor , and 6.5 % for FOB-Gold ( p=0.002 ) . There was no significant difference in diagnostic yield of advanced neoplasia ( 1.4 % for OC-Sensor vs 1.2 % for FOB-Gold ; p=0.15 ) or positive predictive value ( PPV ; 31 % vs 32 % ; p=0.80 ) . When comparing both tests at the same positivity rate instead of cut-off , they yielded similar PPV and detection rates . Conclusions The OC-Sensor and FOB-Gold were equally acceptable to a screening population . However , FOB-Gold was prone to more non-analysable tests . Comparison between FIT br and s is usually done at the same Hb stool concentration . Our findings imply that for a fair comparison on diagnostic yield between FIT 's positivity rate rather than Hb concentration should be used . Trial registration number NTR5385 ; Results This study was conducted to assess the accuracy of an immunochemical occult blood test for detecting  colorectal adenomas with severe dysplasia , and to determine the relationship between the grading of adenomatous dysplasia and the results of this test . Sixteen colorectal adenomas under 1 cm with severe dysplasia , 65 adenomas 1 cm or larger with severe dysplasia , 65 adenomas under 1 cm with mild-to-moderate dysplasia , 65 adenomas 1 cm or larger with mild-to-moderate dysplasia , 65 colorectal cancers and 130 healthy controls were investigated . Each subject was tested with an immunochemical fecal occult blood test  on 3 consecutive days , and the accuracy of the test was evaluated . The detection rate of this test was 13 % for severe dysplasia under 1 cm 45 % for severe dysplasia 1 cm or more , 17 % for mild-to-moderate dysplasia under 1 cm , 40 % for mild-to-moderate dysplasia 1 cm or more , and 89 % for colorectal cancers , and the false positive rate was 5 % , showing a significant difference in the detection rate between severe dysplasias 1 cm or more and those under 1 cm ( P<0.05 ) as well as a significant difference between severe dysplasias 1 cm or more and mild-to-moderate dysplasia under 1 cm ( P<0.01 ) , and between cancers and adenomas ( P<0.001 ) , whereas there was no significant difference between the detection rates for severe dysplasia 1 cm or more and mild-to-moderate dysplasia 1 cm or more . These results indicate that there is no association between the detection rate of this immunochemical occult blood test  for adenomas and the grade of adenomatous dysplasia Differences in the risk of a false negative or a false positive fecal immunochemical test ( FIT ) across subgroups may affect optimal screening strategies . We evaluate whether subgroups are at increased risk of a false positive or a false negative FIT result , whether such variability in risk is related to differences in FIT sensitivity and specificity or to differences in prior CRC risk . R and omly selected , asymptomatic individuals were invited to undergo colonoscopy .  Participants were asked to undergo one sample FIT and to complete a risk question naire . We identified patient characteristics associated with a false negative and false positive FIT results using logistic regression . We focused on statistically significant differences as well as on variables influencing the false positive or negative risk for which the odds ratio exceeded 1.25 . Of the 1,426 screening participants , 1,112 ( 78 % ) completed FIT and the question naire ; 101 ( 9.1 % ) had advanced neoplasia . 102 Individuals were FIT positive , 65 ( 64 % ) had a false negative FIT result and 66 ( 65 % ) a false positive FIT result . Participants at higher age and smokers had a significantly higher risk of a false negative FIT result . Males were at increased risk of a false positive result , so were smokers and regular NSAID users . FIT sensitivity was lower in females . Specificity was lower for males , smokers and regular NSAID users . FIT sensitivity was lower in women . FIT specificity was lower in males , smokers and regular NSAID users . Our results can be used for further evidence based individualization of screening strategies Objective Faecal immunochemical testing ( FIT ) is increasingly used in colorectal cancer ( CRC ) screening but has a less than perfect sensitivity . Combining risk stratification , based on established risk factors for advanced neoplasia , with the FIT result for allocating screenees to colonoscopy could increase the sensitivity and diagnostic yield of FIT-based screening . We explored the use of a risk prediction model in CRC screening . Design We collected data in the colonoscopy arm of the Colonoscopy or Colonography for Screening study , a multicentre screening trial . For this study 6600 r and omly selected , asymptomatic men and women between 50 years and 75 years of age were invited to undergo colonoscopy .  Screening participants were asked for one sample FIT ( OC-sensor ) and to complete a risk question naire prior to colonoscopy . Based on the question naire data and the FIT results , we developed a multivariable risk model with the following factors : total calcium intake , family history , age and FIT result . We evaluated goodness-of-fit , calibration and discrimination , and compared it with a model based on primary screening with FIT only . Results Of the 1426 screening participants , 1112 ( 78 % ) completed the question naire and FIT . Of these , 101 ( 9.1 % ) had advanced neoplasia . The risk based model significantly increased the goodness-of-fit compared with a model based on FIT only ( p<0.001 ) . Discrimination improved significantly with the risk-based model ( area under the receiver operating characteristic ( ROC ) curve : from 0.69 to 0.76 , ( p=0.02 ) ) . Calibration was good ( Hosmer-Lemeshow test ; p=0.94 ) . By offering colonoscopy to the 102 patients at highest risk , rather than to the 102 cases with a FIT result > 50 ng/mL , 5 more cases of advanced neoplasia would be detected ( net reclassification improvement 0.054 , p=0.073 ) . Conclusions Adding risk based stratification increases the accuracy FIT-based CRC screening and could be used in pre selection for colonoscopy in CRC screening programmes Background : Previous studies have suggested that the immunochemical fecal occult blood test has superior specificity for detecting bleeding in the lower gastrointestinal tract even if bleeding occurs in the upper tract . We conducted a large population -based study involving asymptomatic adults in Taiwan , a population with prevalent upper gastrointestinal lesions , to confirm this cl aim . Methods : We conducted a prospect i ve cohort study involving asymptomatic people aged 18 years or more in Taiwan recruited to undergo an immunochemical fecal occult blood test , colonoscopy and esophagogastroduodenoscopy between August 2007 and July 2009 . We compared the prevalence of lesions in the lower and upper gastrointestinal tracts between patients with positive and negative fecal test results . We also identified risk factors associated with a false-positive fecal test result . Results : Of the 2796 participants , 397 ( 14.2 % ) had a positive fecal test result . The sensitivity of the test for predicting lesions in the lower gastrointestinal tract was 24.3 % , the specificity 89.0 % , the positive predictive value 41.3 % , the negative predictive value 78.7 % , the positive likelihood ratio 2.22 , the negative likelihood ratio 0.85 and the accuracy 73.4 % . The prevalence of lesions in the lower gastrointestinal tract was higher among those with a positive fecal test result than among those with a negative result ( 41.3 % v. 21.3 % , p < 0.001 ) . The prevalence of lesions in the upper gastrointestinal tract did not differ significantly between the two groups ( 20.7 % v. 17.5 % , p = 0.12 ) . Almost all of the participants found to have colon cancer ( 27/28 , 96.4 % ) had a positive fecal test result ; in contrast , none of the three found to have esophageal or gastric cancer had a positive fecal test result ( p < 0.001 ) . Among those with a negative finding on colonoscopy , the risk factors associated with a false-positive fecal test result were use of antiplatelet drugs ( adjusted odds ratio [ OR ] 2.46 , 95 % confidence interval [ CI ] 1.21–4.98 ) and a low hemoglobin concentration ( adjusted OR 2.65 , 95 % CI 1.62–4.33 ) . Interpretation : The immunochemical fecal occult blood test was specific for predicting lesions in the lower gastrointestinal tract . However , the test did not adequately predict lesions in the upper gastrointestinal tract Background : Faecal occult blood tests ( FOBTs ) are used for colorectal cancer ( CRC ) screening . We aim ed to assess the sensitivity of an immunochemical FOBT for detecting advanced colorectal neoplasia in the left vs the right colon and to explore reasons for potential differences in site-specific test performance . Methods : We prospect ively measured faecal occult blood levels by a quantitative immunochemical FOBT ( RIDASCREEN ) in 2310 average-risk subjects undergoing screening colonoscopy .  We compared diagnostic performance for subjects with left- vs right-sided advanced neoplasia , as well as patient characteristics and adenoma characteristics that have been suggested to impact faecal haemoglobin levels . Results : Sensitivities for subjects with left- vs right-sided advanced neoplasia were 33 % ( 95 % confidence interval ( CI ) , 26–41 % ) and 20 % ( CI , 11–31 % ) ( P=0.04 ) at a specificity of 95 % ( overall sensitivity : 29 % ) and the areas under the receiver-operating characteristics curve were 0.71 ( CI , 0.69–0.72 ) and 0.60 ( CI , 0.58–0.63 ) , respectively . Pedunculated shape was strikingly more common in participants with left- vs right-sided advanced neoplasia ( 47 % vs 14 % ) . In logistic regression analyses adjusted for site , pedunculated shape was statistically significantly associated with test sensitivity ( P=0.04 ) . Conclusions : The immunochemical FOBT in our study was more sensitive for detecting subjects with left- vs right-sided advanced colorectal neoplasia . Our findings may stimulate further diagnostic research in the field as well as modelling analyses to estimate the potential effect of site-specific test performance on the effectiveness of annual or biennial FOBT-based screening programmes , in particular with respect to protection from right-sided CRC Immunochemical faecal occult blood tests ( I-FOBT ) detect more effectively advanced neoplasia than guaiac tests ( G-FOBT ) . The study aim was to compare the performance of an I-FOBT whilst varying the positivity threshold and considering four analysis modalities : one sample was performed ( MG(1 ) ) , two sample s were performed and at least one sample was positive ( MG(2 + ) ) , both sample s were positive ( MG(2++ ) ) or the mean of the two sample s ' log-transformed haemoglobin contents exceeded the cutoff ( MG(2 m ) ) . Screening for colorectal cancer using both G-FOBT and two sample s ' I-FOBT was performed by an average-risk population sample of 20,322 subjects . Among the 1,615 subjects with at least one positive test , 1,277 had a satisfactory colonoscopy result ; 43 invasive cancers and 270 high-risk adenomas were detected . The I-FOBT was reinterpreted under each analysis modality ( a r and om selection of one sample led 
    Output:
    
The use of anticoagulants was most frequently studied , without a significant effect on FIT positivity .
Age was not found to have a systematic effect on either FIT false‐positivity or false‐negativity in meta‐ analysis .
: Multiple risk factors , known at time of FIT invitation , are associated with false FIT results in CRC screening .