Critical appraisal:Elsafi SH, Alqahtani NI, Zakary NY, Al Zahrani EM 2015

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Risk of bias assessment: diagnostic accuracy study

Patient Selection
Prior tests and any referral filters
Condition that defined entry into study
cohort study protocol, including patients who reported to two tertiary hospitals in the eastern region of Saudi Arabia –

King Fahd Military Medical Complex (Dhahran, Saudi Arabia); and King Faisal Specialist Hospital (Dammam, Saudi Arabia) from June 2012 through May 2013.
All

Setting
All asymptomatic participants that reported to hospital in this study were 50–74 years of age; they were tested once for FOB by two simultaneous methods, and they were scheduled for colonoscopy. Patients who reported symptoms of disease of the lower gastrointestinal tract were excluded.
Was a diagnostic case-control design avoided?
Yes
Consecutive or random sample?
Yes
Did the study avoid inappropriate exclusions?
Yes
Reasons
If comparing more than one index test was the design fully paired or paired randomly?
Not applicable
If a paired randomised design was used, was allocation to groups concealed and was the generation of allocation sequence adequate?
Not applicable
What is the risk that the selection of participants introduced bias?
Low
Comments
Index test 1
Describe index test and how it was conducted and interpreted
gFOBT (ColoScreen) test.
Were the index test results interpreted without knowledge of the results of the reference standard?
Unclear
If a threshold was used, was it pre-specified?
Yes
If two tests are being compared, have they been assessed independently / blind to each other?
Unclear
What is the risk that the conduct or interpretation of the index test introduced bias?
Unclear
Comments
Index test 2
Describe index test and how it was conducted and interpreted, if applicable
FIT
Were the index test results interpreted without knowledge of the results of the reference standard?
Unclear
If a threshold was used, was it pre-specified?
Yes
What is the risk that the conduct or interpretation of the index test introduced bias?
Unclear
Comments
Reference Standard
Describe the reference standard and how it was conducted and interpreted
Colonoscopy.
Is the reference standard likely to correctly classify the target condition?
Yes
Were the reference standard results interpreted without knowedge of the results of the index test/s?
Unclear
Was the reference test standard independent of the index test?
(i.e. the index test did not form part of the reference standard)
Yes
What is the risk that the reference standard, its conduct or interpretation introduced bias?
Unclear
Comments
Flow and timing
Describe any patients who did not receive the index test(s) and/or reference standard or who were excluded from the 2x2 table
Describe the time interval and any interventions between index test(s) and reference standard
If a predictive test (the reference standard is a later event that the test aims to predict) were any subsequent interventions between test and later event blind to test result?
Not applicable
Was there an appropriate interval between index test(s) and reference standard?
Unclear
Did either all participants or a random sample of participants receive a reference standard test?
Yes
Did all patients receive the same reference standard irrespective of index test result?
Yes
Were all test results including unclear results reported?
Yes
Were all patients included in the analysis?
Yes
What is the risk that the patient flow introduced bias?
Unclear
Comments
Overall risk of bias
At risk of bias Additional comments: Please replace this text and include any additional comments in regards to your risk of bias rating


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Article
Elsafi SH, Alqahtani NI, Zakary NY, Al Zahrani EM. The sensitivity, specificity, predictive values, and likelihood ratios of fecal occult blood test for the detection of colorectal cancer in hospital settings. Clin Exp Gastroenterol 2015;8:279-84 Available from: http://www.ncbi.nlm.nih.gov/pubmed/26392783.
Assigned to
User:Albert.chetcuti
Topic area
Guidelines:Colorectal cancer
Clinical question
Form
Form:Quality appraisal quadas


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