Critical appraisal:Schilling D, Spiethoff A, Rosenbaum A, Hartmann D, Eickhoff A, Jakobs R, et al 2005 2

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Critical Appraisal

Article being appraised

Schilling D, Spiethoff A, Rosenbaum A, Hartmann D, Eickhoff A, Jakobs R, et al. Does Cytokeratin7/20 immunoreactivity help to distinguish Barrett's esophagus from gastric intestinal metaplasia? Results of a prospective study of 75 patients. Pathol Res Pract 2005;200(11-12):801-5 Abstract available at http://www.ncbi.nlm.nih.gov/pubmed/15792123.


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
The study included patients undergoing upper GI endoscopy for upper gastrointestinal symptoms with suspected long or short segment Barrett’s esophagus or with an endoscopically normal gastroesophageal junction.
Condition that defined entry into study
Seventy-five patients were enrolled in this study, 26 with long-segments Barrett’s esophagus (BE), 21 with short-segments BE, 13 with intestinal metaplasia (IM) of the cardia (a normal gastroesophageal junction) and 18 with antral IM.
Setting
Department of Gastroenterology and Hepatology at the Academic Medical Hospital of the University of Mainz, Germany.
Was a diagnostic case-control design avoided?
Yes
Consecutive or random sample?
Yes
Did the study avoid inappropriate exclusions?
Yes
Reasons
Exclusion criteria were antibiotic therapy within 10 days before admission, eradication therapy of Helicobactor pylori infection or gastrointestinal pathology related to portal hypertension.
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.
Index test 1
Describe index test and how it was conducted and interpreted
The index test was immunohistochemical staining for CK7 / CK20 in tissue sections taken from endoscopy. Staining patterns were assigned to three categories: Barrett’s pattern (superficial CK 20 staining, superficial CK 7 staining), gastric pattern (superficial and crypt staining of both markers) or other patterns (different from the Barrett’s and gastric types). Dysplastic areas were excluded from analysis. All cases were evaluated independently by two pathologists. Disagreements were settled by common assessment.
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?
Not applicable
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 of staining patterns was performed independently by two pathologists; disagreements being settled by common assessment.
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 formalin-fixation and paraffin embedding of tissue biopsy sections taken during the endoscopy, followed by histologic evaluation of H&E stained sections.
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?
Low
Comments
The reference standard used here is the universally accepted method for diagnosis of Barrett’s esophagus (histological evaluation of H&E stained tissue sections from endoscopy).
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 test 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?
No
What is the risk that the patient flow introduced bias?
Low
Comments
Three patients of the Barrett’s group showed malignant changes and thus were excluded from the analysis.
Size of effect
4 Reason for decision: The CK7 / CK20 immunostaining pattern showed high specificity (97%) but poor sensitivity (30%) in patients with short segment Barrett’s esophagus. For long segment Barrett’s esophagus sensitivity was only 17%. Combined results show cytokeratin staining to be 23% sensitivity and 97% specific for this study.
Relevance of evidence
2 Additional comments: Provides evidence that CK7 / CK20 immunostaining patterns cannot be used for reliable differentiation between incomplete intestinal metaplasia and Barrett’s epithelium. These results do not confirm the findings of Ormsby et al.
Result of appraisal

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Completed by

Melissa Thomas


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Article
Schilling D, Spiethoff A, Rosenbaum A, Hartmann D, Eickhoff A, Jakobs R, et al. Does Cytokeratin7/20 immunoreactivity help to distinguish Barrett's esophagus from gastric intestinal metaplasia? Results of a prospective study of 75 patients. Pathol Res Pract 2005;200(11-12):801-5 Abstract available at http://www.ncbi.nlm.nih.gov/pubmed/15792123.
Assigned to
User:angelique.levert
Topic area
Guidelines:Barrett's
Clinical question
Form
Form:Critical appraisal


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