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

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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:

177

Number of Patients evaluated:

125

Number of samples:

Not applicable


Includes an economic evaluation

no

Evidence ratings

Level of evidence

III-3

Risk of bias
At risk of bias Comments: Please replace this text and include any additional comments in regards to your quality rating

Risk of bias assessment: diagnostic accuracy study

Patient Selection
Prior tests and any referral filters
Patient selection based on confirmed diagnosis following endoscopic examination and evaluation of H&E stained biopsies. In patients with suspected short segment Barrett’s oesophagus (SSBO), at least two biopsy specimens were taken from just below the squamocolumnar junction. If goblet cells were found histologically with Alcian blue staining, the diagnosis was confirmed and cytokeratin 7/20 immunohistochemical stains were performed. Among 88 patients suspected of having SSBO, only 36 patients (40.9%) were confirmed.
Condition that defined entry into study
Thirty-six patients with short-segment (less than 3cm above the oesophagogastric junction) Barrett’s oesophagus, 28 patients with intestinal metaplasia at the cardia and 61 patients with gastric intestinal metaplasia (gastric body or antrum), all of whom were diagnosed by endoscopic and histological examinations, were evaluated in this study.
Setting
A single centre study performed at the 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?
Unclear
Reasons
It was stated that multiple biopsies taken per patient but unclear whether multiple biopsies were analysed. All results were reported in terms of patients but it was not stated whether all biopsies for this patient supported the result or only a subset.
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 the utility of cytokeratin immunostaining for the distinguishing between SSBO and gastric intestinal metaplasia in the Korean population.
Index test 1
Describe index test and how it was conducted and interpreted
Index test is immunohistochemical staining of tissue sections for Cytokeratin-7 / Cytokeratin-20 (CK7/CK20) pattern for its utility in identification of Barrett’s oesophagus (BO), as hypothesized by Ormsby et al (1999). 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. Whether multiple pathologists undertook independent evaluation of the staining was not stated.
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?
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 unknown.
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 from biopsies taken during endoscopic examination. Alcian blue staining (pH2.5) was also performed to positively 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?
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, with additional Alcian blue staining to identify mucin-containing goblet cells.
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?
No
What is the risk that the patient flow introduced bias?
Low
Comments
Patient specimens for both the index test and reference standard were taken in a single endoscopy session. No further interaction with the patients was required.
Size of effect
4 Reason for decision: The Barrett’s cytokeratin 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. The reported specificity is the combined results of all gastric intestinal metaplasia (cardia (n=28), gastric body and antrum (more heavily weighted, n=61). 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%. Multiple biopsies were taken per patient but it was unclear whether all biopsies were analysed. Results were reported in terms of patients but it was not stated whether all biopsies for this patient supported the result or only a subset. Implications of this on the reported sensitivity and specificity are unclear.
Relevance of evidence
4 Additional comments: Provides some evidence that CK7 / CK20 immunostaining pattern can be used to aid in the differentiation of short-segment Barrett’s oesophagus from gastric intestinal metaplasia in the Korean population. 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:Reginald.lord
Topic area
Guidelines:Barrett's
Clinical question
Form
Form:Critical appraisal


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