Review for 10.1186/s12876-020-01491-w (2020)

Reviewer’s report
Title: 
Adverse events of video capsule endoscopy over the past two decades: a
systematic review and proportion meta-analysis
Version: 
0 
Date: 
15 Aug 2020
Reviewer's report:
This is a systematic review with a meta-analysis aimed to quantify 
1) the rates of all VCE adverse events, 
2) assessing the potential predictors of each adverse event and 
3) demonstrating whether the rates changed over the past 20 years.
General comment: the authors addressed several clinical relevant points; they
used a one proportion meta-analysis to describe the events involved. This is a
descriptive meta-analysis with a lot of figures, but many of those are
unnecessary.
Major point 
Include in the title one proportion meta-analysis.
The authors included any paper reporting adverse events of VCE but excluded
case reports or studies with fewer than 50 patients: please clarify the reasons for
this cut off. 
At page 12 the authors state that "as for the case-controlled studies and
randomized controlled trials (RCT), the data of each group were extracted
separately"; does this mean that the same paper was considered for each arm? 
Include a supplementary table on the technical characteristic of the VCE. 
In the section Factors and Predictors associated with small bowel incomplete
examination rate, consider analyzing the temporal trend and the changing rate by
different technical aspects of the VCE. 
Use the random or fixed model as appropriate and in the figures report the
appropriate model i.e. fixed or random.
Consider performing a sensitivity analysis subgrouping the papers by RCT,
retrospective and prospective studies.
Declare in the statistical section how you handle paper with zero or missing
event.
There are too many figures; remove the unnecessary ones and report a self-
explaining text for any figure in the supplementary file.
Include in the text the Forrest plot for the primary outcomes.
Minor comment
Use a multivariate term instead of multivariable.
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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?
No
Are the methods sufficiently described to allow the study to be repeated?
No
Is the use of statistics and treatment of uncertainties appropriate?
No
Is the presentation of the work clear?
No
Are the images in this manuscript (including electrophoretic gels and blots) free
from apparent manipulation?
No