Critical appraisal:Kurtkaya-Yapicier O, Gencosmanoglu R, Avsar E, Bakirci N, Tozun N, Sav A 2003 2

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Critical Appraisal

Article being appraised

Kurtkaya-Yapicier O, Gencosmanoglu R, Avsar E, Bakirci N, Tozun N, Sav A. The utility of cytokeratins 7 and 20 (CK7/20) immunohistochemistry in the distinction of short-segment Barrett esophagus from gastric intestinal metaplasia: Is it reliable? BMC Clin Pathol 2003 Dec 2;3(1):5 Abstract available at http://www.ncbi.nlm.nih.gov/pubmed/14651756.


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
Two groups of endoscopic biopsy specimens were examined, including 20 specimens of short-segment Barrett’s oesophagus and 20 specimens with gastric intestinal metaplasia accompanied by H.pylori associated gastritis.
Condition that defined entry into study
Endoscopy specimens of the patients referred from Marmara University Institute of Gastroenterology were reviewed from the files of the Department of Pathology at the same university between 1998 and 2002.
Setting
Marmara University Institute of Gastroenterology, Istanbul, Turkey.
Was a diagnostic case-control design avoided?
Yes
Consecutive or random sample?
No
Did the study avoid inappropriate exclusions?
Yes
Reasons
Cases without goblet cell metaplasia (by Alcian Blue staining) were excluded from the study (applicable for both groups of patients).
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
Index test is immunohistochemical staining of tissue sections for cytokeratin-7 and -20 (CK7 /CK 20) pattern. The characteristic BE pattern is defined by strong diffuse CK7 positivity in superficial and deep glands accompanied by CK20 positivity in the surface epithelium and superficial glands.
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
The number of pathologists performing the CK7/CK20 pattern analysis (and whether evaluation was performed independently) was not specified. Whether they were blinded to reference standard results is not known.
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), Alcian blue pH 2.5 and Alcian blue pH 0.5 were used to identify neutral mucin, sialomucin and sulphomucin respectively. 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 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?
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
4 Reason for decision: The sensitivity of the CK7 / CK20 pattern for identification of short-segment Barrett’s oesophagus was particularly poor (10%; 100% specificity). There was no significant difference for Barrett’s CK7/CK20 pattern between the two groups (p=0.487).
Relevance of evidence
6 Additional comments: Provides evidence that CK7 / CK20 immunostaining cannot be used to reliably differentiate between short-segment Barrett’s oesophagus and gastric intestinal metaplasia.
Result of appraisal

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Completed by

Melissa Thomas


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Article
Kurtkaya-Yapicier O, Gencosmanoglu R, Avsar E, Bakirci N, Tozun N, Sav A. The utility of cytokeratins 7 and 20 (CK7/20) immunohistochemistry in the distinction of short-segment Barrett esophagus from gastric intestinal metaplasia: Is it reliable? BMC Clin Pathol 2003 Dec 2;3(1):5 Abstract available at http://www.ncbi.nlm.nih.gov/pubmed/14651756.
Assigned to
User:angelique.levert
Topic area
Guidelines:Barrett's
Clinical question
Form
Form:Critical appraisal


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