Critical appraisal:Yim HJ, Lee SW, Choung RS, Kim YS, Kim JY, Lee HS, et al 2005 2

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Critical Appraisal

Article being appraised

Yim HJ, Lee SW, Choung RS, Kim YS, Kim JY, Lee HS, et al. Is cytokeratin immunoreactivity useful in the diagnosis of short-segment Barrett's oesophagus in Korea? Eur J Gastroenterol Hepatol 2005 Jun;17(6):611-6 Abstract available at http://www.ncbi.nlm.nih.gov/pubmed/15879722.


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-2


Risk of bias assessment: diagnostic accuracy study

Patient Selection
Prior tests and any referral filters
In patients with Barrett’s oesophagus (diagnosed endoscopically), at least two biopsy specimens were taken from just below the squamocolumnar junction. If goblet cells were found histologically with alcian blue staining, cytokeratin 7/20 immunohistochemical stains were performed. Intestinal metaplasia at the cardia was diagnosed whenever biopsy specimens taken from within 2cm below the oesophagogastric junction revealed intestinal metaplasia.
Condition that defined entry into study
Thirty-six patients with short-segment (less than 3cm above the oesophagogastric junction upon endoscopic examination) Barrett’s oesophagus, 28 patients with intestinal metaplasia at the cardia and 61 patients with gastric intestinal metaplasia at locations other than the cardia (gastric body, antrum), all of whom were diagnosed by endoscopic and histological examinations, were included in this study.
Setting
Departments of Internal Medicine and Pathology; Institute of Digestive Diseases and Nutrition, Korea University of Medicine, Seoul, Korea.
Was a diagnostic case-control design avoided?
Yes
Consecutive or random sample?
Unclear
Did the study avoid inappropriate exclusions?
No
Reasons
It was mentioned that of the 88 patients suspected of having short-segment Barrett’s oesophagus, it was only histologically confirmed in 36 of these. These 36 patients were the used as the Barrett’s group for the study, however it is unclear whether the remaining 52 patients were discarded or some were tested as part of the intestinal metaplasia of the cardia group. Exclusion of these patients may create bias in test specificity.
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
Patients were all of Korean origin, however this was the intended aim of the study – to evaluate cytokeratin immunoreactivity for the diagnosis of short-segment Barrett’s oesophagus in Korea.
Index test 1
Describe index test and how it was conducted and interpreted
Index test is immunostaining for cytokeratin-7 (CK7) and cytokeratin-20 (CK20) pattern to aid in the diagnosis of short segment Barrett’s oesophagus. Barrett’s cytokeratin 7/20 pattern was defined as CK20 positivity in only the superficial glands, combined with CK7 positivity in both the superficial and deep 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
It was not stated whether the interpretation of staining patterns was performed by a number of independent pathologists or a single pathologist, nor whether the test results were interpreted without knowledge of the reference standard results.
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, paraffin embedding of tissue biopsy sections taken during endoscopic examination, followed by histologic evaluation of H&E stained sections. Alcian blue staining (pH2.5) was also performed to identify goblet cells required for the diagnosis of Barrett’s oesophagus.
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 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?
No
What is the risk that the patient flow introduced bias?
Low
Comments
Patient specimens were obtained for all testing at a single endoscopy session. No further interaction with patients was required.
Size of effect
2 Reason for decision: Barrett’s cytokeratin 7/20 pattern was observed in 28 of 36 cases with short-segment Barrett’s oesophagus (77.8% sensitivity) with a quoted specificity of 77.5% in Korean patients. However it must be noted that this specificity is the combined results of the intestinal metaplasia at the cardia and gastric intestinal metaplasia (more heavily weighted) groups. More accurately, the specificity should be reported as false positives in 11 of 28 patients with intestinal metaplasia at the cardia – a specificity of 60.7%.
Relevance of evidence
2 Additional comments: Provides some evidence that CK7 / CK20 immunostaining pattern can be used to aid in the diagnosis of short-segment Barrett’s oesophagus in the Korean population, however the rate of false positives is poor. Does not provide evidence that the test improves outcome for the patient.
Result of appraisal

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Melissa Thomas


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Article
Yim HJ, Lee SW, Choung RS, Kim YS, Kim JY, Lee HS, et al. Is cytokeratin immunoreactivity useful in the diagnosis of short-segment Barrett's oesophagus in Korea? Eur J Gastroenterol Hepatol 2005 Jun;17(6):611-6 Abstract available at http://www.ncbi.nlm.nih.gov/pubmed/15879722.
Assigned to
User:angelique.levert
Topic area
Guidelines:Barrett's
Clinical question
Form
Form:Critical appraisal


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