Critical appraisal:Lee YC, Chiu HM, Chiang TH, Yen AM, Chiu SY, Chen SL, et al 2013 2

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Risk of bias assessment: diagnostic accuracy study

Patient Selection
Prior tests and any referral filters
requested to complete three types

of stool tests and undergo bidirectional endoscopy;

Condition that defined entry into study
>18 years of age who had completed the FIT, guaiacbased

test, HPSA and bidirectional endoscopy were
included. also recruited
participants in whom gastrointestinal tract cancers were
suspected by the non-invasive screening test, such as radiology
and oral inspection,

those participants who underwent only one
endoscopy for detection of a cancerous lesion were still
eligible because it was rare (approximately 0.9%) for one
subject to have important lesions in the upper as well as
lower gastrointestinal tracts in the cancer screening
group.
participants who had overt
gastrointestinal bleeding, including haematemesis, tarry
stools, melena or hematochezia. We also excluded participants
with histories of a gastrectomy and/or colectomy
and pregnant or lactating women.

Setting
hospital-based

and community-based screening sources; hospital based used to evaluate perforamce of test and community based to confirm reproducibility and applicability of the strategy in the community.

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?
Yes
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
mailed one collection

card for the highly sensitive guaiac-based test
(Hemoccult SENSA Single Slides; Beckman Coulter, Inc,
USA), one sampling tube for HPSA (Easy One
Step Test; Firstep Bioresearch, Inc, Taiwan)

1-day method for all
stool tests and advised participants to start diet and drug
restrictions 3 days before they obtained the stool samples
and to obtain stool samples within 2 days before starting
the bowel preparation

Two technicians executed the guaiac-based and
H pylori stool antigen tests and read the results independently;

Were the index test results interpreted without knowledge of the results of the reference standard?
Yes
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?
Yes
What is the risk that the conduct or interpretation of the index test introduced bias?
Low
Comments
Index test 2
Describe index test and how it was conducted and interpreted, if applicable
mailed one collection

card for the highly sensitive guaiac-based test
(Hemoccult SENSA Single Slides; Beckman Coulter, Inc,
USA), and FIT (OC-SENSOR; Eiken Chemical Co, Ltd, Tokyo, Japan)

1-day method for all
stool tests and advised participants to start diet and drug
restrictions 3 days before they obtained the stool samples
and to obtain stool samples within 2 days before starting
the bowel preparation

Two technicians executed the guaiac-based and
H pylori stool antigen tests and read the results independently;

FIT was processed at the hospital’s
central laboratory using an automated reader

Were the index test results interpreted without knowledge of the results of the reference standard?
Yes
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?
Low
Comments
Reference Standard
Describe the reference standard and how it was conducted and interpreted
Endoscopic findings and histological results. Participants were given polyethylene

glycol for bowel preparation, which they drank at least
4 h before endoscopic examinations. participants
were advised to stop anticoagulant or antiplatelet
therapy for 7 days. Oesophagogastroduodenoscopy and
colonoscopy were performed by nine experienced
endoscopists, each with a minimum experience of 5000
colonoscopies. Endoscopic findings were recorded electronically
with information on quality of preparation,
completeness of colonoscopy, endoscopic findings and
whether or not a biopsy was performed

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
All included
Describe the time interval and any interventions between index test(s) and reference standard
Stool samples were brought to

the hospital on the screening day and tested immediately.

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?
Yes
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?
Low
Comments
Overall risk of bias
At risk of bias Additional comments: Unclear if reference was interpreted blinded to index test results.


Jutta's tick icon.png This appraisal has been completed.


Article
Lee YC, Chiu HM, Chiang TH, Yen AM, Chiu SY, Chen SL, et al. Accuracy of faecal occult blood test and Helicobacter pylori stool antigen test for detection of upper gastrointestinal lesions. BMJ Open 2013 Oct 30;3(10):e003989 Available from: http://www.ncbi.nlm.nih.gov/pubmed/24176798.
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Topic area
Guidelines:Colorectal cancer
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