PONE-D-22-33436Causal association between leisure sedentary behaviors, physical activity and musculoskeletal health: a Mendelian randomization studyPLOS ONE

Dear Dr. Su,

Thank you for submitting your manuscript to PLOS ONE. After careful consideration, we feel that it has merit but does not fully meet PLOS ONE’s publication criteria as it currently stands. Therefore, we invite you to submit a revised version of the manuscript that addresses the points raised during the review process.

Please submit your revised manuscript by Mar 09 2023 11:59PM. If you will need more time than this to complete your revisions, please reply to this message or contact the journal office at plosone@plos.org. When you're ready to submit your revision, log on to https://www.editorialmanager.com/pone/ and select the 'Submissions Needing Revision' folder to locate your manuscript file.

Please include the following items when submitting your revised manuscript:

• A rebuttal letter that responds to each point raised by the academic editor and reviewer(s). You should upload this letter as a separate file labeled 'Response to Reviewers'.
• A marked-up copy of your manuscript that highlights changes made to the original version. You should upload this as a separate file labeled 'Revised Manuscript with Track Changes'.
• An unmarked version of your revised paper without tracked changes. You should upload this as a separate file labeled 'Manuscript'.

If you would like to make changes to your financial disclosure, please include your updated statement in your cover letter. Guidelines for resubmitting your figure files are available below the reviewer comments at the end of this letter.

If applicable, we recommend that you deposit your laboratory protocols in protocols.io to enhance the reproducibility of your results. Protocols.io assigns your protocol its own identifier (DOI) so that it can be cited independently in the future. For instructions see: https://journals.plos.org/plosone/s/submission-guidelines#loc-laboratory-protocols. Additionally, PLOS ONE offers an option for publishing peer-reviewed Lab Protocol articles, which describe protocols hosted on protocols.io. Read more information on sharing protocols at https://plos.org/protocols?utm_medium=editorial-email&utm_source=authorletters&utm_campaign=protocols.

We look forward to receiving your revised manuscript.

Kind regards,

Renato Polimanti, Ph.D.

Academic Editor

PLOS ONE

Journal Requirements:

When submitting your revision, we need you to address these additional requirements.

1. Please ensure that your manuscript meets PLOS ONE's style requirements, including those for file naming. The PLOS ONE style templates can be found at 

https://journals.plos.org/plosone/s/file?id=wjVg/PLOSOne_formatting_sample_main_body.pdf and https://journals.plos.org/plosone/s/file?id=ba62/PLOSOne_formatting_sample_title_authors_affiliations.pdf

2. We note that the grant information you provided in the ‘Funding Information’ and ‘Financial Disclosure’ sections do not match. 

When you resubmit, please ensure that you provide the correct grant numbers for the awards you received for your study in the ‘Funding Information’ section.

3. Thank you for stating in your Funding Statement: 

"This project was supported by the National Natural Science Foundation of China (8200153156) and Xinglin Scholars Project of Chengdu University of Traditional Chinese Medicine (BSH2020009)."

Please provide an amended statement that declares *all* the funding or sources of support (whether external or internal to your organization) received during this study, as detailed online in our guide for authors at http://journals.plos.org/plosone/s/submit-now.  Please also include the statement “There was no additional external funding received for this study.” in your updated Funding Statement. 

Please include your amended Funding Statement within your cover letter. We will change the online submission form on your behalf.

4. Thank you for stating the following financial disclosure: 

"This project was supported by the National Natural Science Foundation of China (8200153156) and Xinglin Scholars Project of Chengdu University of Traditional Chinese Medicine (BSH2020009).The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript."

We note that one or more of the authors is affiliated with the funding organization, indicating the funder may have had some role in the design, data collection, analysis or preparation of your manuscript for publication; in other words, the funder played an indirect role through the participation of the co-authors. If the funding organization did not play a role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript and only provided financial support in the form of authors' salaries and/or research materials, please do the following:

a. Review your statements relating to the author contributions, and ensure you have specifically and accurately indicated the role(s) that these authors had in your study. These amendments should be made in the online form.

b. Confirm in your cover letter that you agree with the following statement, and we will change the online submission form on your behalf: 

“The funder provided support in the form of salaries for authors [insert relevant initials], but did not have any additional role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript. The specific roles of these authors are articulated in the ‘author contributions’ section.”"

5. PLOS requires an ORCID iD for the corresponding author in Editorial Manager on papers submitted after December 6th, 2016. Please ensure that you have an ORCID iD and that it is validated in Editorial Manager. To do this, go to ‘Update my Information’ (in the upper left-hand corner of the main menu), and click on the Fetch/Validate link next to the ORCID field. This will take you to the ORCID site and allow you to create a new iD or authenticate a pre-existing iD in Editorial Manager. Please see the following video for instructions on linking an ORCID iD to your Editorial Manager account: https://www.youtube.com/watch?v=_xcclfuvtxQ

Additional Editor Comments:

although reviewers appreciated the manuscript, they also found several major issues that should be addressed.

To be considered for publication, the authors should fully address the problems highlighted by reviewers in a revised submission.

[Note: HTML markup is below. Please do not edit.]

Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

1. Is the manuscript technically sound, and do the data support the conclusions?

The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented.

Reviewer #1: Yes

Reviewer #2: Partly

**********

2. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #1: Yes

Reviewer #2: Yes

**********

3. Have the authors made all data underlying the findings in their manuscript fully available?

The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified.

Reviewer #1: Yes

Reviewer #2: Yes

**********

4. Is the manuscript presented in an intelligible fashion and written in standard English?

PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here.

Reviewer #1: Yes

Reviewer #2: Yes

**********

5. Review Comments to the Author

Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #1: Summary Paragraph

The authors present a Mendelian Randomization study assessing the potential causal associations between leisure sedentary behaviors and physical activity phenotypes and a variety of musculoskeletal disorders such as lower-back pain, intervertebral disc disorder, rheumatoid arthritis, and bone mineral density. This work has the potential of increasing the understanding of the potential causal relationships between known risk factors for musculoskeletal disorders and this outcome using genetically based instrumental variables. One of my main concerns is the use of strong causal language in the title, discussion section and conclusions. Another concern is the reduced scope of interpretations of these results in the discussion (more extensive explanations about biological mechanism [e.g., from SNPs to tissues], and about potential clinical relevance would be needed).

Strengths:

The authors explained well the background of the study and justification for using MR. Exposure and outcome variables are clear in the introduction and throughout the manuscript. The authors outlined well how the exposure and outcome variables have a plausible relationship. The assumptions and the study design were described clearly and tested, quality control and selection of genetic instruments were also well outlined.

Weaknesses or areas for improvement:

Since biological mechanisms, their interaction across time, type and time of measurements and MR assumptions play a crucial role here, the use of strong causal language in the title, discussion section and conclusions could undermine the words of caution when interpreting results from MR analyses.

Points for clarification are outlined below by section.

Title:

• I’d suggest the authors to add the word “Potential” before “Causal association (…)” in the title.

Abstract:

• (p. 8) Usually MR hypotheses include causal language or language inferring the potential causality. In the abstract’s background, the authors use “related”, which hints more to non-directional associations in their hypothesis.

Introduction:

• (p. 9) I'd suggest to clarify "It" after the reference call #7. Although it can be assumed what the authors are talking about, it is usually best to specify the subject of the new sentence, especially after a long multi-clause one.

• (p. 9) Add a few examples of the unique benefits of exercise for the musculoskeletal system.

Method:

• (p. 10) Although it might be assumed that the participants for the two phenotypes of PA have European ancestry, specify if this is the case in the corresponding paragraph under the 2.2 subsection.

• (p. 11) Add an “Ancestry” column in Table 1 if multiple ancestries were used. A column listing the data sources for each Consortium could also be helpful for Table 1 (or this list could also be in the notes part of Table 1 to save space).

• (p. 12) It would be interesting to inspect the differences of significance from unadjusted p-values to at least two multiple-testing adjustments. The authors included the Bonferroni adjustment, which is conservative and may increase Type-II error. Would the authors be able to estimate p-values under a less conservative method (e.g., false discovery rate adjustment) and add them next to the Bonferroni adjusted ones?

• Were any power calculations performed prior to the analysis? Whether these calculations were performed or not, it would be interesting to see the differences in statistical power from each sample.

• Are the authors able to provide more information about the covariates beyond BDM? And mention whether these covariates were adjusted for across samples or not?

• Would the authors be able to provide information about the characteristics of missing data? And if present, how the missingness was addressed?

• Were this study and its protocols pre-registered? If so, where can the reader find them?

Results:

• Since this study used a two-sample MR approach, are the authors able to include information about the variant-exposure correlations between the samples of exposure and outcome phenotypes? And, would the authors also be able to include any report of participant overlap between exposure and outcome samples?

• Did the authors test the direction of causation in the opposite direction (i.e., outcome -> exposure, or bidirectional MR)? Many biological mechanisms are complex and might include feedback loops that may hint scientist to test the plausibility of the reverse direction of causation (e.g., causal influences of outcome on exposure at unmeasured timepoints). If the authors tested this direction, would they be able to provide the results? If they didn’t test it, would they be able add this supplementary analysis to test this direction?

Discussion:

• Would the authors be able to discuss any potential clinical relevance and public health applications of these results beyond the discussion provided?

• The authors mentioned in the limitations paragraph that these results cannot be generalized to populations of other ancestries different than European, which is true. Are the authors able to discuss the importance of expanding the genetic and phenotypic research more to non-European ancestries? If so, would they inform the reader about their effort to find datasets/summary-stats of non-European ancestry for their analyses in this manuscript?

• (p. 15-16) I’d suggest to add “potential” before “causal relationship” in the following sentence “(…), the MR study revealed the causal relationship between LSB/PA and different musculoskeletal disorders (…)” and also in the many occurrences of “causal relationship” or “causal association” or other similar assertions throughout the discussion section and also importantly, in the Conclusions. It is always important to use causal language cautiously in MR studies.

Figures:

• This might be an issue of the pdf convertor, but I’d encourage the authors to double check that figures (and any image-based object/file) do not pixelate. Otherwise reading small letters or visualizing shapes can become difficult. I suggest to use vector-based images.

Other:

• Is there a link where readers can find the code used for the analyses? This can enhance transparency and reproducibility.

Reviewer #2: 1. The GWAS’s used have all been on individuals with European ancestry. I would request the authors to replicate these findings or at least perform these analyses in GWAS’s of other ancestries.

2. I would like the authors to perform the bi-directional MR also i.e. from musculoskeletal disorders to LSB/PA

3. It is not clear to me why did the authors select RA, LBP, IVDD for musculoskeletal disorders? Were they just examples? Why did the authors not select carpal tunnel syndrome and tendonitis?

4. I would like the authors to elaborate on the sensitivity analyses and the results in the discussion section a bit more.

**********

6. PLOS authors have the option to publish the peer review history of their article (what does this mean?). If published, this will include your full peer review and any attached files.

If you choose “no”, your identity will remain anonymous but your review may still be made public.

Do you want your identity to be public for this peer review? For information about this choice, including consent withdrawal, please see our Privacy Policy.

Reviewer #1: No

Reviewer #2: No

**********

[NOTE: If reviewer comments were submitted as an attachment file, they will be attached to this email and accessible via the submission site. Please log into your account, locate the manuscript record, and check for the action link "View Attachments". If this link does not appear, there are no attachment files.]

While revising your submission, please upload your figure files to the Preflight Analysis and Conversion Engine (PACE) digital diagnostic tool, https://pacev2.apexcovantage.com/. PACE helps ensure that figures meet PLOS requirements. To use PACE, you must first register as a user. Registration is free. Then, login and navigate to the UPLOAD tab, where you will find detailed instructions on how to use the tool. If you encounter any issues or have any questions when using PACE, please email PLOS at figures@plos.org. Please note that Supporting Information files do not need this step.

Potential causal association between leisure sedentary behaviors, physical activity and musculoskeletal health: a Mendelian randomization study

PONE-D-22-33436R1

Dear Dr. Su,

We’re pleased to inform you that your manuscript has been judged scientifically suitable for publication and will be formally accepted for publication once it meets all outstanding technical requirements.

Within one week, you’ll receive an e-mail detailing the required amendments. When these have been addressed, you’ll receive a formal acceptance letter and your manuscript will be scheduled for publication.

An invoice for payment will follow shortly after the formal acceptance. To ensure an efficient process, please log into Editorial Manager at http://www.editorialmanager.com/pone/, click the 'Update My Information' link at the top of the page, and double check that your user information is up-to-date. If you have any billing related questions, please contact our Author Billing department directly at authorbilling@plos.org.

If your institution or institutions have a press office, please notify them about your upcoming paper to help maximize its impact. If they’ll be preparing press materials, please inform our press team as soon as possible -- no later than 48 hours after receiving the formal acceptance. Your manuscript will remain under strict press embargo until 2 pm Eastern Time on the date of publication. For more information, please contact onepress@plos.org.

Kind regards,

Renato Polimanti, Ph.D.

Academic Editor

PLOS ONE

Additional Editor Comments (optional):

The authors adequately addressed reviewers' concerns and the manuscript is now suitable for publication in PLOS One.

Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

1. If the authors have adequately addressed your comments raised in a previous round of review and you feel that this manuscript is now acceptable for publication, you may indicate that here to bypass the “Comments to the Author” section, enter your conflict of interest statement in the “Confidential to Editor” section, and submit your "Accept" recommendation.

Reviewer #1: All comments have been addressed

**********

2. Is the manuscript technically sound, and do the data support the conclusions?

The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented.

Reviewer #1: Yes

**********

3. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #1: Yes

**********

4. Have the authors made all data underlying the findings in their manuscript fully available?

The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified.

Reviewer #1: Yes

**********

5. Is the manuscript presented in an intelligible fashion and written in standard English?

PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here.

Reviewer #1: Yes

**********

6. Review Comments to the Author

Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #1: (No Response)

**********

7. PLOS authors have the option to publish the peer review history of their article (what does this mean?). If published, this will include your full peer review and any attached files.

If you choose “no”, your identity will remain anonymous but your review may still be made public.

Do you want your identity to be public for this peer review? For information about this choice, including consent withdrawal, please see our Privacy Policy.

Reviewer #1: No

**********