Review for 10.1186/s12876-022-02132-0 (2022)

Reviewer’s report
Title: 
Are Gastrointestinal Symptoms Associated with Higher Risk of Mortality
in COVID-19 Patients? A Systematic Review and Meta-Analysis
Version: 
3 
Date: 
09 Jan 2022
Reviewer's report:
PEER REVIEWER ASSESSMENTS: 
OBJECTIVE - Full research articles: is there a clear objective that addresses one
or several testable research questions? (Brief or other article types: is there a
clear objective?)
Yes - there is a clear objective
DESIGN - Is the current approach (including controls and analysis protocols)
appropriate for the objective?
Yes - the approach is appropriate
EXECUTION - Are the experiments and analyses performed with sufficient
technical rigor to allow confidence in the results?
Yes - experiments and analyses were performed appropriately
STATISTICS - Is the use of statistics in the manuscript appropriate?
No - there are issues with the statistics in the study
INTERPRETATION - Is the current interpretation/discussion of the results
reasonable and not overstated?
Yes - the author's interpretation is reasonable
OVERALL MANUSCRIPT POTENTIAL - Has the author addressed your
concerns sufficiently for you to now recommend the work as a technically sound
contribution? If not, can further revisions be made to make the work technically
sound?
Probably - with minor revisions
PEER REVIEWER COMMENTS: 
GENERAL COMMENTS: Thanks for the opportunity to review the amended
manuscript. The authors have carefully responded including some additional
analyses. I have a few more comments arising from the additional analyses.
REQUESTED REVISIONS: 
Pg 9, lines 240-248 I cannot see how the subgroup analysis has clearly shown the
higher risk for older ages but the subgroup analysis by age is showing the
opposite. I would suggest kindly check the studies included in the age group
categories. I would also check all other analysis parameters to make sure 
this is
correct.
Page 11, line 279-281. I suggest adding here a comment to indicate that 'older
age may be a significant predictor of poor prognosis in COVID-19 patients with
GI symptoms.'
Pg 13, line 349 (Conclusion opening sentence) I suggest adding at the end of the
sentence, 'except in older patients (60 yrs and over)'.
ADDITIONAL REQUESTS/SUGGESTIONS: 
The authors have addressed all previous comments but the analysis by sub-age
groups have raised new questions due to the inconsistency with the other age-
related analysis. I am suggesting the authors review the included studies and
ensure these are correct for both of the age related analysis.
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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?
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Yes
Is the use of statistics and treatment of uncertainties appropriate?
No
Is the presentation of the work clear?
Yes
Are the images in this manuscript (including electrophoretic gels and blots) free
from apparent manipulation?
Yes