Effectiveness of Bariatric Surgeries for Metabolic Dysfunction-Associated Steatotic Liver Disease: A Systematic Review and Meta-Analysis

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

Dear Authors,

Thank you for submitting this systematic review and meta-analysis. This study addresses an interesting topic that is certainly relevant to surgical practice, however there are some issues that should be addressed before publication can be considered:

1) In 2023, an international consensus changed the name and definition from NAFLD to MASLD (Rinella ME, Lazarus JV, Ratziu V, et al. A multisociety Delphi consensus statement on new fatty liver disease nomenclature. Hepatology. 2023;78(6):1966-1986) - yet you chose to use the old nomenclature. You should either change it across the whole article, and possibly include the new name in the literature search; or address and explain why you chose the old name. It would be interesting to perform a literature search with the new name, and the conclude if a change in search strategy is required or not.

2) Some of the forest plots are not clear, as they miss the "0 line" showing if there is a significant difference or not, e.g. figure 2 and figure 5. It is important that readers can understand the figures clearly, so they need to be re-drawn, and the scale needs to be changed for more clarity (otherwise the diamond will stretch too much).

3) The baseline characteristics of the studies are not reported, which would strengthen the assumption that we are comparing similar populations. In fact, the non-significant difference in post-operative BMI between RYGB and LSG makes me think that the populations are in fact not similar and that there is some bias that has not been accounted for.

4) Sonographic evidence of fatty liver, or more robust methods of assessment (like biopsy, MRI fat fraction, elastography, etc.) would strengthen the assumption that bariatric surgery is an effective treatment for MASLD. I appreciate that this might not be available in the studies, but you should address this and explain the limitation of your analysis.

5) The significance of these findings should be made clearer, i.e. why reducing MASLD is important for the clinician and for the patient.

I would be happy to review a revised version on this manuscript, if these suggestions are taken on board.

Comments on the Quality of English Language

There are numerous corrections that are required, as well as punctuation errors. Just a few examples for reference:

- Page 1, line 27: the sentence is probably missing a verb.

- Page 2, line 60: the full text of all studies was "conducted" (incorrect verb).

- Page 2, line 76: the sentence is not intelligible.

Etc.

Even the title has a punctuation error (a space before the : and not after). I recommend a thorough revision of spelling, grammar, and punctuation.

Author Response

Please see the attachment

Author Response File: Author Response.docx

Reviewer 2 Report

Comments and Suggestions for Authors

The authors should be commended for their rigorous effort in conducting a comprehensive systematic review that is methodologically robust.

I have the following comments:

1.     It is recommended to include a detailed section on the Meta-Analysis methodology within the Materials and Methods. This should encompass the criteria for study selection, data extraction processes, and statistical techniques employed.

2.     The choice between fixed-effect and random-effects models for conducting the meta-analysis should not solely be based on the heterogeneity of the included studies. The selection of the appropriate model should be guided by the design and methodological characteristics of the studies included.

3.     In Table 1, it would be more concise to merge the two separate sample size columns into a single column. Additionally, consider adding a summary row at the end of the table to provide an overview of the data presented.

4.     The manuscript should provide a more detailed discussion on the distinct pathophysiological mechanisms underlying Roux-en-Y gastric bypass (RYGB) and sleeve gastrectomy. Elaborate on how these mechanisms contribute to weight loss and their potential effects on NAFLD.

5.     In the Discussion section, it is important to place your findings within the context of existing literature. Elaborate on how your results compare with previous studies and discuss the implications of your findings in light of current knowledge.

These revisions will enhance the clarity, comprehensiveness, and impact of the manuscript.

Author Response

1. It is recommended to include a detailed section on the Meta-Analysis methodology within the Materials and Methods. This should encompass the criteria for study selection, data extraction processes, and statistical techniques employed.

Reply:

We specified all details about study selection, data extraction processes, and statistical techniques as required.

2. The choice between fixed-effect and random-effects models for conducting the meta-analysis should not solely be based on the heterogeneity of the included studies. The selection of the appropriate model should be guided by the design and methodological characteristics of the studies included.

 

Reply:

We revised the analyses which were done in the random effects model due to the heterogeneity between included studies as most of them included NAFLD and NASH patients without specifying their data we explained this in the methods, corrected the results section, and explained these details in the limitations section.

3. In Table 1, it would be more concise to merge the two separate sample-size columns into a single column. Additionally, consider adding a summary row at the end of the table to provide an overview of the data presented.

Reply:

We merged both columns and the summary row was added.

 

4. The manuscript should provide a more detailed discussion of the distinct pathophysiological mechanisms underlying Roux-en-Y gastric bypass (RYGB) and sleeve gastrectomy. Elaborate on how these mechanisms contribute to weight loss and their potential effects on NAFLD.

Reply:

We added the mechanism of action section in the discussion.

 

5. In the Discussion section, it is important to place your findings within the context of existing literature. Elaborate on how your results compare with previous studies and discuss the implications of your findings in light of current knowledge.

Reply:

The implications of the results are added in the discussion.

 

Author Response File: Author Response.docx

Round 2

Reviewer 2 Report

Comments and Suggestions for Authors

The authors sufficiently addressed my comments.