Critical appraisal:Ormsby AH, Vaezi MF, Richter JE, Goldblum JR, Rice TW, Falk GW, et al 2000 2

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Critical Appraisal

Article being appraised

Ormsby AH, Vaezi MF, Richter JE, Goldblum JR, Rice TW, Falk GW, et al. Cytokeratin immunoreactivity patterns in the diagnosis of short-segment Barrett's esophagus. Gastroenterology 2000 Sep;119(3):683-90 Abstract available at http://www.ncbi.nlm.nih.gov/pubmed/10982762.


Applicable clinical question

Key Facts

Study Design

diagnostic accuracy study

Number of Patients enrolled:

Not applicable

Number of Patients evaluated:

Not applicable

Number of samples:

Not applicable


Includes an economic evaluation

no

Evidence ratings

Level of evidence

III-1


Risk of bias assessment: diagnostic accuracy study

Patient Selection
Prior tests and any referral filters
Helicobactor pylori infection status was available for patients as a result of an ongoing study assessing the role of H.pylori in patients with Barrett’s oesophagus.
Condition that defined entry into study
Endoscopic biopsy specimens from patients with long-segment Barrett’s Oesophagus (BE) (n=49), suspected short-segment BE (n=43) and gastric intestinal metaplasia (IM) (n=26) were identified and from the files of The Cleveland Clinic Foundation spanning a 3-year period (1996-1998) and evaluated.
Setting
The Cleveland Clinic Foundation, Cleveland, Ohio, USA.
Was a diagnostic case-control design avoided?
Yes
Consecutive or random sample?
No
Did the study avoid inappropriate exclusions?
Unclear
Reasons
A total of 127 patients were selected, with only 118 evaluated. 7 patients were excluded from analysis as a result of poor orientation of biopsy (required to differentiate superficial and deep mucosa). A further 2 patients were excluded due to interoberserver discrepancies.
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
Patient selection did not exclude any particular subset of samples that would bias analysis. No exclusions were made based on hiatus hernia status or H.pylori infection.
Index test 1
Describe index test and how it was conducted and interpreted
Index test is immunohistochemical staining for cytokeratin-7 / cytokeratin-20 (CK7/CK20) pattern for its utility in identification of short-segment Barrett’s Oesophagus (BE). A Barrett’s CK7/CK20 pattern was considered present if CK20 staining was seen in surface epithelium and superficial glands and diffuse CK7 staining was present in both superficial and deep glands in areas of intestinal metaplasia. Independent assessment of CK7/CK20 staining was undertaken by two gastrointestinal pathologists with experience in the interpretation of cytokeratin immunoreactivity patterns obtained from a previously published study.
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?
Low
Comments
Interpretation was performed by two independent pathologists with experience in interpretation of CK7/CK20 staining.
Index test 2
Describe index test and how it was conducted and interpreted, if applicable
Not 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
Not applicable.
Reference Standard
Describe the reference standard and how it was conducted and interpreted
Reference standard was histological evaluation of H&E stained sections of FFPE tissue taken during endoscopic examination. Periodic acid Schiff (PAS) and Alcian blue pH 2.5 were used to positively identify mucin-containing goblet cells. Giemsa stain was used to reveal H.pylori.
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?
Yes
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?
Low
Comments
The reference standard used here is the universally accepted method for diagnosis of Barrett’s oesophagus.
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 patients who received the index test also received the reference standard.
Describe the time interval and any interventions between index test(s) and reference standard
Tissue samples for the reference standard and index test were taken at a single endoscopy session, hence no intervention between index test and reference standard is possible.
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
Patient specimens were selected from a database and tissue blocks were accessed to obtain samples. No further interaction with patients was required.
Size of effect
1 Reason for decision: CK7/CK20 pattern identified long-segment BE with a 98% sensitivity and 100% specificity. Short-segment BE showed only slightly reduced sensitivity (82%) with 100% specificity. It should be noted that interpretation of the CK7/CK20 is highly complex with several caveats that could result in misinterpretation, such as the absence of CK20 staining in areas of dysplasia/adenocarcinoma, the presence of CK7 staining in non-specialised columnar mucosa, and the weak intensity of CK7 in patients with Barrett’s mucosa.
Relevance of evidence
2 Additional comments: Provides evidence that CK7/CK20 immunostaining can be used to identify not only patients with long-segment Barrett’s oesophagus but also those with short-segment Barrett’s oesophagus who have a similar profile to that seen in long-segment BE (preponderance of white males, high frequency of hiatial hernia and low frequency of h.pylori infection). Does not provide evidence that the test improves outcome for the patient.
Result of appraisal

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Completed by

Melissa Thomas


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Article
Ormsby AH, Vaezi MF, Richter JE, Goldblum JR, Rice TW, Falk GW, et al. Cytokeratin immunoreactivity patterns in the diagnosis of short-segment Barrett's esophagus. Gastroenterology 2000 Sep;119(3):683-90 Abstract available at http://www.ncbi.nlm.nih.gov/pubmed/10982762.
Assigned to
User:angelique.levert
Topic area
Guidelines:Barrett's
Clinical question
Form
Form:Critical appraisal


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