PONE-D-22-16915Usefulness of muscle ultrasound in appendicular skeletal muscle mass estimation for sarcopenia assessmentPLOS ONE

Dear Dr. Kim,

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.

ACADEMIC EDITOR:Dear Authors, two experts in the field reviewed your manuscript and found several criticisms you should address during the revision process.

Please submit your revised manuscript by Oct 27 2022 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,

Emiliano Cè

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. Thank you for stating the following in the Acknowledgments Section of your manuscript: 

This work was supported by the Industrial Technology Innovation Program (No. 20008842), funded by the Ministry of Trade, Industry & Energy (MOTIE, Korea). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

However, funding information should not appear in the Acknowledgments section or other areas of your manuscript. We will only publish funding information present in the Funding Statement section of the online submission form. 

Please remove any funding-related text from the manuscript and let us know how you would like to update your Funding Statement. Currently, your Funding Statement reads as follows: 

This work was supported by the Industrial Technology Innovation Program (No. 20008842), funded by the Ministry of Trade, Industry & Energy (MOTIE, Korea). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

Please include your amended statements within your cover letter; we will change the online submission form on your behalf.

3. Please review your reference list to ensure that it is complete and correct. If you have cited papers that have been retracted, please include the rationale for doing so in the manuscript text, or remove these references and replace them with relevant current references. Any changes to the reference list should be mentioned in the rebuttal letter that accompanies your revised manuscript. If you need to cite a retracted article, indicate the article’s retracted status in the References list and also include a citation and full reference for the retraction notice.

[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: No

**********

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

Reviewer #1: Yes

Reviewer #2: N/A

**********

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: Thanks to the authors for their good job. Sarcopenia is an important issue in aging societies and increasing comorbidities. This article could be a fine guide for the detection and management of sarcopenia. In this respect, I think it will contribute to the literature.

Reviewer #2: Dear Editor,

the manuscript entitled "Usefulness of muscle ultrasound in appendicular skeletal muscle mass estimation for

sarcopenia assessment" explore the use of ultrasound (US) as a simple, cheap, and non-invasive tool to assess sarcopenia.

To this purpose, 212 participants have been enrolled to the study.

I found the reading fluent and the english correct, however, I have some major concerns about the paper content.

1. Aiming to investigate whether muscle ultrasonography is an effective tool for estimating the appendicular skeletal muscle mass (ASM), the authors combined some parameters, among which some US measurements, into two equations (one for men and one for women). Then, they compared the estimated ASM to the one determined by a BIA analysis.

I found this approach questionable as BIA is not the gold standard for ASM assessment. Indeed, ASM is not a BIA direct measure but has to be derived by equation, therefore, its accuracy depends on which equation is adopted by the device. Moreover, other factors influence BIA measurements like hydration status, age, and body mass. About this latter, it has been found that BIA tends to underestimate ASM in overweight people. Even though the equations developed by the authors to estimate ASM took into account age, sex, and body mass, the measure used as reference value cannot be considered equal to the one determined by DXA or CT or MRI. In addition, ASM was estimated by authors feeding the equations with EI values determined during US measurements. Such index, however, has to be considered with cautions as its reliability is age-dependent (Strasser 2013) and it is influenced by several factors among which hydration status, probe position, and probe settings. Even though the reliability of the measure was good, the equations developed by the authors and used to estimate ASM, can be considered valid only in this specific study, with their specific US device, its settings and their operator. These equations on different laboratories may perform differently.

2. The other limit I found in the study relates to the US ability to discriminate lowASM people. Indeed, after having determined ASM on 212 participants, the authors found that 21 showed low ASM values and, by a ROC analysis, determined a cut-off value on the MT of some muscles. In my opinion the sample size of low ASM group was too poor to return a reliable value.

MINOR

1. In my opinion the introduction is too vague and should be improved, taking care in the terminology. The rationale is not clear and the paragraph dealing with sarcopenia should be delved more deeply. A complete definition of sarcopenia should be given: "Sarcopenia is a progressive, generalized, age-related loss of skeletal muscle mass [1]." is reductive. Notwithstanding the authors continued citing the association to loss of muscle strength and the reduction of physical activity, the offical definition of sarcopenia considers sarcopenia as concurrent reduction of skeletal muscle mass, muscle strength and functional physical performance. This latter is different from "physical activity".

"Historically, muscle mass has been measured using several imaging techniques, including dualenergy

X-ray absorptiometry, computed tomography, and magnetic resonance imaging." Which of these technique is considered the gold standard?

"Muscle ultrasound is a noninvasive, cost-effective, and easily accessible imaging technique for the evaluation of neuromuscular disorders [5]." I find this sentence unnecessary.

"This study aimed to investigate whether muscle ultrasonography is an effective tool for estimating the appendicular skeletal muscle mass (ASM) in terms of muscle quantity and quality." ASM should be introduced previously, in sarcopenia paragraph otherwise it is not clear why it represents a variable of interest. Moreover, given that the authors previously reported "muscle ultrasonography has been suggested as a valuable tool for assessing sarcopenia because it can assess both muscle quantity and quality" it is not clear which is the novelty of the present study. It seems this study aims to confirm something that is already known.

"In addition, we explored whether muscle ultrasonography can be used as a screening tool for sarcopenia in middle-aged and older individuals" please, explain why you chose such target of population. Is there any reason for involving middle-aged and old individuals?

"A hold-out cross-validation method was used to develop and validate the ASM prediction equation." Why did the authors have to validate an ASM prediction equation? The reader has to be previously be informed that US-derived ASM relies on prediction equation. Moreover, the authors should explain the reason why they proposed a different equation.

Please, do not use WEIGHT but BODY MASS

Please, provide an explanation about the test administered in Clinical assessment. Why did they test handgrip and gait speed, and analyzed body composition?

Pleae explain why ASM has been normalized to height.

Please, explain the criteria adopted to choose the muscles that have been measured (why BB, TB, RF ad BF)?

Please, explain why calf muscles have not been considered.

Please, it is recommended to provide all the information about US measurements: gain, frequency of the transducer beam, depth of penetrance, probe length.

As ROI appears only two times, I suggest to remove the acronymus.

In the statistical analysis, did the authors check for differences between DEVELOPMENT and cross-validation GROUP?

"Low ASM group was defined as, based on AWGS 2019 consensus, ASM index < 7.0 kg/m2 for men and < 5.7 kg/m2 for women." Please, provide a reference

Being sarcopenia a combination of muscle mass loss, low muscle strength and reduced functionality, did the authors investigate the correlation between functional parameters and ASM values?

Table 1 To make it more readable, I suggest to use only one column to show mean+/- SD and to thicken the column border of Model development goup and cross-validation group

Please, check that measure units are always present.

"The estimated ASM did not significantly differ from the measured ASM in either the men or the women groups (p = 0.749 and p = 0.548, respectively; Fig. 2)" Does this sentence relate to MODEL DEVELOPMENT group?

"without a significant systematic error in the Bland–Altman plot (p = 0.091 and p = 0.056, respectively; Fig. 3)." from which analysis, do these values derive?

Table 4. Differences in the measured and estimated appendicular skeletal muscle mass in the cross-validation group" I would appreciate a Bland_altman plot of these data.

About "Cut-off value in ultrasound-derived parameters for sarcopenia screening" I found questionable diagnosing sarcopenia on ASM alone. Similarly, I found questionable performing statistical analysis on samples with such diversity in size.

"Table 5. Comparison between subjects in the normal and low ASM groups." These results come from a statistical analysis that compared groups of different size (within male comparison: 83 vs 8 particpants; within female comparison: 108 vs 13 participants). There is no mention in statistical analysis paragraph about this comparison and, in any case, the size is so different that the results lose validity.

Please add references to:

"In addition, muscle ultrasonography has been suggested as a valuable tool for assessing sarcopenia because it can assess both muscle quantity and quality."

"Low ASM group was defined as, based on AWGS 2019 consensus, ASM index < 7.0 kg/m2 for men and < 5.7 kg/m2 for women"(reference is lacking)

**********

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.

PONE-D-22-16915R1Usefulness of muscle ultrasound in appendicular skeletal muscle mass estimation for sarcopenia assessmentPLOS ONE

Dear Dr. Kim,

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.

==============================

ACADEMIC EDITOR: Two experts in the field reviewed your manuscript. They both found your new manuscript version decisively improved. Still Reviewer 2 has raised some minors issues that you should consider while revising the manuscript.==============================

Please submit your revised manuscript by Jan 20 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,

Emiliano Cè

Academic Editor

PLOS ONE

Journal Requirements:

Please review your reference list to ensure that it is complete and correct. If you have cited papers that have been retracted, please include the rationale for doing so in the manuscript text, or remove these references and replace them with relevant current references. Any changes to the reference list should be mentioned in the rebuttal letter that accompanies your revised manuscript. If you need to cite a retracted article, indicate the article’s retracted status in the References list and also include a citation and full reference for the retraction notice.

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

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

Reviewer #2: (No Response)

**********

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

Reviewer #2: Yes

**********

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

Reviewer #1: Yes

Reviewer #2: 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

Reviewer #2: 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

Reviewer #2: 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)

Reviewer #2: Dear Authors,

I appreciate your efforts in addressing most of my comments. I just have few minor concerns that I'd like to put to your attention.

In some comments I asked you to kindly explain your choices (comment 7, 8, 10, 11, and 12). You carefully addressed the comment in the Response section but, if I've seen correctly, you did not insert the explanation in the manuscript. My recommendations did not aim at receiving an explanation for myself rather providing more details to the readers by adding further explanantions in the text. Most of the times I had the answer so I was asking you to improve the manuscript by going deep insight for the readers.

Table 1 is almost ok. I personally do not appreciate decimals when they lose sense. For example: are two decimals essentials when the order of the measure unit is centimeters or millimeters? I understand that the table appears neater when every value is reported with two decimals but I wonder if the second decimals of a millimeter-based value has any sense.

In Conclusion I'd suggest a mitigation of the sentence "Muscle ultrasonography can be an effective tool for....." with something like "Muscle ultrasonography seems/appears be an effective tool for..."

**********

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

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.

PONE-D-22-16915R2Usefulness of muscle ultrasound in appendicular skeletal muscle mass estimation for sarcopenia assessmentPLOS ONE

Dear Dr. Kim,

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.

==============================

ACADEMIC EDITOR: Dear Authors, your manuscript has been revised by an expert in the field that found some minor issues.

Please submit your revised manuscript by Feb 02 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,

Emiliano Cè

Academic Editor

PLOS ONE

Journal Requirements:

Please review your reference list to ensure that it is complete and correct. If you have cited papers that have been retracted, please include the rationale for doing so in the manuscript text, or remove these references and replace them with relevant current references. Any changes to the reference list should be mentioned in the rebuttal letter that accompanies your revised manuscript. If you need to cite a retracted article, indicate the article’s retracted status in the References list and also include a citation and full reference for the retraction notice.

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

Reviewers' comments:

[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.

Usefulness of muscle ultrasound in appendicular skeletal muscle mass estimation for sarcopenia assessment

PONE-D-22-16915R3

Dear Dr. Kim,

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,

Emiliano Cè

Academic Editor

PLOS ONE

Additional Editor Comments (optional):

Reviewers' comments: