Critical appraisal:Chowdhury ATMD, Longcroft-Wheaton G, Davis A, Massey D, Goggin P 2014 2
From Cancer Guidelines Wiki
Risk of bias assessment: diagnostic accuracy study
Patient Selection
Prior tests and any referral filters
- Patients were referred for the investigation of IDA
Condition that defined entry into study
- IDA
Setting
- Single secondary care hospital UK
Was a diagnostic case-control design avoided?
- Yes
Consecutive or random sample?
- Unclear
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?
- Unclear
Comments
Index test 1
Describe index test and how it was conducted and interpreted
- IDA was the index test of interest.
An MCV of less than 82 with a serum ferritin <12 was required for inclusion, which accounted for 90% of the recruited
patients. However, it was recognised that ferritin is an indirect measure of iron stores. It is an acute-phase protein and will be elevated in the presence of inflammation. Therefore, in cases where ferritin was normal, then serum iron, total iron binding capacity (TIBC)
and transferrin were measured. If serum iron was less than 65 mg/dL, with an elevated TIBC greater than
66 mmol/L and transferrin saturation of less than 15%, patients were included regardless of MCV or ferritin.
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?
- No
What is the risk that the conduct or interpretation of the index test introduced bias?
- High
Comments
Index test 2
Describe index test and how it was conducted and interpreted, if applicable
- The main index test in the paper is the FOBT test, but this is not an index test we are looking at.
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
- Colonoscopy "as per standard protocol" was performed by endoscopist for all participants.
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)
(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
- 317 patients were initially enrolled but 25 failed to complete the study either for not returning all of their FOB kits or by declining definitive investigation.
Describe the time interval and any interventions between index test(s) and reference standard
- FOB test performed before colonoscopy
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?
- No
What is the risk that the patient flow introduced bias?
- High
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 |
This appraisal has been completed.
- Article
- Chowdhury ATMD, Longcroft-Wheaton G, Davis A, Massey D, Goggin P. Role of faecal occult bloods in the diagnosis of iron deficiency anaemia. Frontline Gastroenterology 2014 Oct 1;5(4):231-36.
- Assigned to
- User:Victoria.freeman
- Topic area
- Guidelines:Colorectal cancer
- Clinical question
- Form
- Form:Quality appraisal quadas
- Outcomes
- Positive predictive values
Section below only relevant for Cancer Council Project Officer