Critical appraisal:Church TR, Wandell M, Lofton-Day C, Mongin SJ, Burger M, Payne SR, et al 2014

From Cancer Guidelines Wiki

Risk of bias assessment: diagnostic accuracy study

Patient Selection
Prior tests and any referral filters
Condition that defined entry into study
Setting
Subjects at least 50 years old and scheduled for colonoscopy at

one of the participating clinical centres were approached about
volunteering for the study. To ensure that only average risk individuals
were enrolled, we excluded those with previous lower
endoscopy, previous CRC or adenomas; iron deficiency anaemia
or haematochezia (blood in the stool) within the previous
6 months; or family history indicating increased risk for the
disease (two or more first degree relatives with CRC or one or
more with CRC at age 50 years or less; or known Lynch syndrome
or familial adenomatous polyposis).

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
At least 1 day before initiating colonoscopy preparation,

enrolled eligible subjects provided informed consent for the
study, baseline information and a single whole blood draw into
four 10 ml potassium ethylenediaminetetraacetic acid blood
tubes. Plasma was isolated from whole blood,10 aliquoted into
coded 2 ml cryotubes and stored at −80°C. Aliquot batches
were periodically shipped on dry ice to a central repository for
−80°C storage.

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?
Not applicable
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
Were the index test results interpreted without knowledge of the results of the reference standard?
Not applicable
If a threshold was used, was it pre-specified?
Not applicable
What is the risk that the conduct or interpretation of the index test introduced bias?
Not applicable
Comments
Reference Standard
Describe the reference standard and how it was conducted and interpreted
Because the intent was to evaluate the assay in the context of

routine screening and the centres used were experienced at
screening, no attempt at study wide control of colonoscopy or
pathology procedures or quality was made. Rather, colonoscopy
procedures, including polypectomy and biopsy, were performed
by board certified endoscopists at each of the participating
centres using board specific screening standards and site specific
standards for sedation, monitoring, imaging and equipment.
This was to mimic actual screening to the extent possible.
Histopathology, diagnostic procedures, and staging of biopsy
and surgical specimens used routine procedures at each site.
Colonoscopy and pathology reports, including completion and
preparation quality, were abstracted onto study forms and
entered into the database.

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?
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: Please replace this text and include any additional comments in regards to your risk of bias rating


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


Article
Church TR, Wandell M, Lofton-Day C, Mongin SJ, Burger M, Payne SR, et al. Prospective evaluation of methylated SEPT9 in plasma for detection of asymptomatic colorectal cancer. Gut 2014 Feb;63(2):317-25 Available from: http://www.ncbi.nlm.nih.gov/pubmed/23408352.
Assigned to
User:Albert.chetcuti
Topic area
Guidelines:Colorectal cancer
Clinical question
Form
Form:Quality appraisal quadas


Section below only relevant for Cancer Council Project Officer

Edit appraisal assignment