Review for 10.1186/1471-230X-13-44 (2013)

Reviewer's report
Title:Linear Echoendoscope-Guided ERCP for the Diagnosis of Occult Common
Bile Duct Stone
Version: 1Date:13 September 2012
Reviewer: Hjalmar van Santvoort
Reviewer's report:
This is a prospective observational cohort study on the diagnostic accuracy of
linear EUS in detecting CBD stones. The authors are to be commended for
performing an nice study on this interesting new diagnostic modality on which
new data are welcomed. There are, however, substantial shortcomings to the
study design that need to be acknowledged by the authors and require toning
down the conclusion of the paper
I have some suggestions for improving the manuscript:
Major Compulsory Revisions:
INTRODUCTION:
1. The current aim of the study as formulated at the end of the introduction is
misleading; please delete “as an alternative to both MRCP and radial EUS” as
this was not a comparative study. Moreover, “the potential” is rather vague. I
would rephrase the introduction to state clearly the goal of the study, which in my
opinion was: “the aim of this study was to investigate the safety and diagnostic
accuracy of linear EUS in detecting occult CBD stones”.
METHODS :
2. The inclusion criteria are not clear: what if CBD stones were seen on
conventional US; were these patients included in the current study? Moreover, in
the aim of the study it is stated that patients with “intermediate risk for CBD
stones” are studies; how was “intermediate” defined in the eligibility criteria?
3. An exclusion criterion was the presence of CBD stones on conventional US/
CT scan. Hence, the patient population of this study is highly selected and the
results of this study can not be extrapolated to all patients with clinical of
biochemical suspicion of CBD stones. This is not a problem, as long as the
authors clearly state that the study focused only on patients were conventional
imaging failed to identify CBD stones. In this respect, it should be reported in the
results section whether all 30 patients underwent transabdominal US and/or CT
before they were included in the study. The issue should also be emphasized in
the discussion section.
4. From a methodological point of view: the diagnostic test in this study was
linear EUS. The gold standard was ERCP. However, the gold standard was not
performed in all patients; if EUS was negative patients did not receive ERCP.
This may have led to a false negative result, underestimating the diagnostic
accuracy of EUS. The issue should be addressed in the discussion section as a
major shortcoming.
RESULTS:
5. In 15 patients the reason for inclusion was acute pancreatitis. This was,
however, not defined as an inclusion criterion in the methods section. Were there
other signs of CBD stones in the patients? Were there other plausible causes for
pancreatitis in these patients, as it may be an overkill in diagnosis to perform
EUS in every patient with acute pancreatitis
DISCUSSION
6. As previously stated the fact that the study population represents a subgroup
of patients with suspicion of CBD stones and the fact that ERCP was not
performed as the gold standard in all patients should be addressed in the
discussion. This also means that the conclusion is currently much to strong.
Please state in the conclusion only something like “ this study suggests that
linear EUS can accurately detect CBD stones in patients were conventional
imaging techniques have failed”
Minor Essential Revisions
INTRODUCTION
7. The introduction could be shortened; for instance by moving background
information on linear EUS to the discussion section.
METHODS
8. In the last paragraph of the methods section (page 9, line 15) the study design
is clearly stated. Move this information to the beginning of the methods section.
9. an the authors provide a rationale for the sample size of 30 patients? If this
was arbitrarily chosen, please also state this.
RESULTS
10. Of the 12 patients with positive EUS, 2 patients “were false-positive cases”.
Why were these false-positives? Did these patients undergo ERCP, and if so,
was ERCP performed immediately following EUS? If not, the CBD stones may
have migrated before ERCP was performed.
GENERAL
11. Please add an abstract to the manuscript
12. Although the paper is generally well written, there is still some room for
improving grammar and style; e.g. (page 4, line 7) do not use past tense “stones
were 77.3%..” but “stones are”; and (page 4, line 10) do not use “has been the
gold standard” but “is the gold standard”.
13. Do use decimals when presenting percentages ; e.g. 15% instead of 15.1%
Level of interest: An article whose findings are important to those with closely
related research interests
Quality of written English: Needs some language corrections before being
published
Statistical review: No, the manuscript does not need to be seen by a
statistician.
Declaration of competing interests:
no