Review for 10.1186/s12876-025-03789-z (2025)

Title: Effect of Synbiotics on the Cardiovascular Risk Factors in Patients with Non- alcoholic
Fatty Liver: A GRADE Evidence Systematic Review, Meta-analysis
Version: 0 Date: 09 Feb 2025
Reviewer:  Ali Jafari
Reviewer's report:
I had the privilege of reviewing the article "Effect of Synbiotics on the Cardiovascular Risk
Factors in Patients with Non-alcoholic Fatty Liver: A GRADE Evidence Systematic Review,
Meta-analysis" While the topic is of significant importance, the manuscript exhibits several
methodological and linguistic issues. I have substantial concerns regarding its current form and
believe it is not suitable for publication until these concerns are comprehensively addressed. I
commend the authors for their valuable contribution and kindly request that they address the
following points:
1. The Cochrane Handbook recommends that a meta-analysis involve more than two individuals,
typically including at least three independent reviewers (two for screening, quality assessment,
and data extraction, and one to resolve discrepancies). However, your study appears to have
only two authors. Could you clarify how the independent review process, as outlined by the
Cochrane criteria, was implemented in your study? Specifically, were the steps of screening,
quality assessment, and data extraction conducted independently to minimize bias? If so, please
provide details on how this was achieved with only two authors. If not, it raises concerns about
the methodological rigor of your study, as it may not fully adhere to the Cochrane standards for
systematic reviews and meta-analyses.
2. The study presents a comprehensive analysis; however, it is unclear why dose-response
analysis and meta-regression were not conducted. These methods are often employed to explore
potential dose-dependent relationships and to investigate sources of heterogeneity among
studies. Could the authors clarify the rationale for omitting these analyses? If applicable,
incorporating such analyses could strengthen the study's findings and provide deeper insights
into the relationships under investigation.
3. The results section of the article would not benefit from a clear presentation of the findings
from the subgroup analysis.
4. Table 1 should provide a clear and comprehensive summary of the key characteristics of the
included studies. Specifically, it would be beneficial to include details such as study name, study
design, health condition, participant demographics (e.g., sex), mean BMI, outcomes measured,
and the type of supplement investigated. This information is essential for readers to evaluate the
context and applicability of the findings.
5. In Table 3, the inclusion of additional subgroup analyses—such as by country of study,
intervention dose, and study quality—would significantly enhance the identification of potential
sources of heterogeneity and improve the generalizability of the findings. The current subgroup
analyses are limited in scope, and expanding them to include these additional characteristics
would provide deeper insights and make the results more compelling and informative for readers.
I recommend that the authors consider incorporating these subgroup analyses to strengthen the
study's interpretability and relevance.
6. In the study figures, arranging the studies chronologically (by time) would improve the clarity
and interpretability of the results.
7. The manuscript should be reported following the PRISMA 2020 statement: an updated
guideline for reporting systematic reviews. Figure 1 may consider using an updated version.
8. The authors have reported results according to the PRISMA checklist. Please include a copy
of the PRISMA checklist (with page numbers indicated for each section) as a supplementary
appendix, as required by PRISMA.
9. Please report the confidence intervals for I2.
10. Using I2 is a measure of consistency between studies. Provide tau2 as an absolute measure
for heterogeneity between studies.
11. What was the reason that you used the SMD, was it not possible to calculate the WMD?
12. You can consider using newer methods like the Hartung-Knapp adjustment.
13. The introduction is a critical part of any manuscript, as it prepares the reader to engage with
the subject matter. I recommend restructuring the introduction to adopt a more expressive and
coherent format.
14. The objective of this article is not explicitly defined. Please clarify the study's purpose clearly
and concisely.
15. Did the authors explore other potential sources for eligible articles, such as grey literature?
If so, please provide detailed information about this process.
16. Data screening and selection should include kappa statistics between the authors.
17. I suggest that the authors provide the full electronic search strategy for all databases,
including any limits used, as a supplementary file to ensure reproducibility.
18. Results were duplicated in both the text and tables/figures. To improve readability, avoid
such duplication.
19. The discussion requires extensive revision, including a more detailed explanation of the
study results. Additionally, consider discussing various factors that may have influenced the
findings.
20. The clinical implications of this study should be explained more thoroughly to the reader.
21. Discuss the limitations and gaps related to this study, including suggestions for future
research directions.
22. Revise the conclusion to make it more concise and impactful. A clear and well-written
conclusion is essential for leaving a strong impression.
23. The manuscript should be reviewed by a native English speaker. Additionally, certification
for language editing should be provided.