Review for 10.1186/s12876-021-01663-2 (2021)

Reviewer’s report
Title: 
Endoscopic transmural drainage is associated with improved outcomes in disconnected pancreatic
duct syndrome: A systematic review and meta-analysis
Version: 
0 
Date: 
08 Dec 2020
Reviewer's report:
Many thanks for the opportunity to review this study on disconnected pancreatic duct syndrome.
The study background and its aims are very clear. The authors wanted to provide a systematic review of
the current knowledge on this very significant clinical aspect of necrotising acute pancreatitis.
In general, this is a very well executed meta-analysis and systematic review. However, I would like to
recommend a few points are addressed before the study is accepted for publication in BMC
Gastroenterology. Although a recent similar study from van Dijk et al. in 2019 in Pancreatology focused
on the same problem, this manuscript identified more studies and a larger less heterogeneous population.
1. The study protocol has not been registered on Prospero, which increases the risk of reporting bias.
Sadly, this issue cannot be resolved in retrospect.
2. How were the disagreements between the study authors resolved (selection, assessment of the risk of
bias and quality)?
3. Who did the data extraction? Was it done by two authors independently (like the selection and risk
assessment). How were the disagreements resolved?
4. There was no data extraction, and no results are presented on patient characteristics (age, gender ratio
etc.) and other details of the management, which would help clinicians to put the results in context. The
etiologies of acute and chronic pancreatitis cases would be of interest to the readership as well. The
authors should attempt to extract and present these data too. 
5. There doesn't seem to be a logic behind the order of the studies in Table 1. I could not detect either
alphabetical or chronological order.
5. The chapter of Quality assessment in the Result section is very difficult to make sense of. I would
recommend that a figure or table summarising the quality of included studies is one of the main figures
and is not exiled to supplementary materials. Also, I would present the results of the quality assessment
after the detailed presentations of the results (study characteristics, presentation and diagnosis, endoscopic
drainage, surgical treatment, and percutaneous drainage). Finally, I would not recommend the use of the
Newcastle Ottawa scale, the Robin I assessment tool is much more suitable for non-randomised studies.
6. There are 1355 patients included in the study. Of those, 942 had the presentations classified (PFC, EPS,
ascites). What about the other 413? Also, 964 had an aetiology (AP, CP, trauma). Again what about the
others? Authors should declare that they did not have information on the others if that is the case.
7. Figures are of low quality, barely legible. These are certainly not suitable for publication in their current
form.
8. My major criticism is the lack of interpretation of the heterogeneities in the meta-analytical
calculations. The methods section does mention that the authors will assess the statistical heterogeneity by
I2 statistics, yet there is no mention of these results. I believe this study is incomplete without the
interpretation of the significant heterogeneities seen in some of the meta-analytical calculations. The
authors should attempt to explain the significant heterogeneities (perhaps by subgroup analyses or
identification of individual studies accounting for it).
9. In general, the discussion s very thorough, however, I would recommend that the authors include three
chapters before the conclusions (Strengths and limitations, Implications for research, and Implication for
practice).
10. A few typos will need correction. For example:
Instead of Manel-Haenszel use Mantel-Haenszel
"There was no difference was found" (page 15 line 5)
I congratulate the authors for the completion of this comprehensive study. I recommend this study for
publication in BMC Gastroenterology with the revisions recommended.
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Is the study design appropriate to answer the research question (including the use of appropriate controls),
and are the conclusions supported by the evidence presented?
Yes
Are the methods sufficiently described to allow the study to be repeated?
Yes
Is the use of statistics and treatment of uncertainties appropriate?
Yes
Is the presentation of the work clear?
Yes
Are the images in this manuscript (including electrophoretic gels and blots) free from apparent
manipulation?
Yes