PONE-D-22-34000Effect of weight limit set as a body weight percentage on work-related low back pain among workersPLOS ONE

Dear Dr. Iwakiri,

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 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,

Yee Guan Ng, 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. In your Data Availability statement, you have not specified where the minimal data set underlying the results described in your manuscript can be found. PLOS defines a study's minimal data set as the underlying data used to reach the conclusions drawn in the manuscript and any additional data required to replicate the reported study findings in their entirety. All PLOS journals require that the minimal data set be made fully available. For more information about our data policy, please see http://journals.plos.org/plosone/s/data-availability.

Upon re-submitting your revised manuscript, please upload your study’s minimal underlying data set as either Supporting Information files or to a stable, public repository and include the relevant URLs, DOIs, or accession numbers within your revised cover letter. For a list of acceptable repositories, please see http://journals.plos.org/plosone/s/data-availability#loc-recommended-repositories. Any potentially identifying patient information must be fully anonymized.

Important: If there are ethical or legal restrictions to sharing your data publicly, please explain these restrictions in detail. Please see our guidelines for more information on what we consider unacceptable restrictions to publicly sharing data: http://journals.plos.org/plosone/s/data-availability#loc-unacceptable-data-access-restrictions. Note that it is not acceptable for the authors to be the sole named individuals responsible for ensuring data access.

We will update your Data Availability statement to reflect the information you provide in your cover letter.

Additional Editor Comments:

The results of this study including the methodology employed is a very interesting study.

However, I particularly concur with comments from reviewer one.

Please carry out the necessary improvement as per comments provided.

In addition, I am also intrigue with the methodology employed.

Specifically, why was the load weight classified?

What was the reference for the brackets of weight category?

In addition, how did the analysis take into consideration of the severity of LBP?

[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: Partly

Reviewer #2: Yes

**********

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: No

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: No

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: Many valuable information was collected with an aim to understand the association between LBP and lifting risk variables. Although the authors examined the effectiveness of the current Japanese lifting standard using a percentage of body weight as the weight limit in reducing LBP, the authors did not explore other risk estimates using ISO or NIOSH methods. Most discussion does not add any value to the current science. What the study could have done is to use various risk calculation methods to determine which combination of the risk variables in the dataset is associated with the prevalence of LBP. The author could have even used some of the posture variables in combination of the weight limit as evidence for supporting the association. The suggested new findings may be used as the base for revising the Japan’s inadequate lifting standard using a percentage of body weight as the limit. The manuscript does have some merit that is worth publishing after a major revision that addresses the above general comment and the below specific comments.

Line 24: the sentence “Moreover,……” in unclear. What are the categories of the constant load weights?

Line 111: Ten items are listed for examining job demands. If ten items were used, the lowest possible scores for job demands should be 10 assuming the Likert scale 1-4 was used. No variables are listed for job control and social support. Please add the info because these two additional variables were used in the study. What was the cut-off point of the score used for low and high stress? Please clarify.

Line 115: For clarity, I suggest the sentence from lines 92-93 for LBP be moved to LBP section (Lines 114-122).

Line 124-128: Please specify if the posture and postural changes are for the trunk or torso, otherwise, the postures asked could mean hand, arm, and other body joints.

Lines 155-158: Excluding the participants that performed push/pull or lifting more than 55 kgs is not justified well. Although there are recommended weight limits in various standard, participants who lifted more than 55 kg should be included in the analysis. Excluding pushing/pulling tasks is less concerning.

Line 167: Please explain what “forced entry metho” is? Add the reference groups for all the variables to the text, unless Tables have the info. Add a description for the dependent variables, such as linear or categorical multiple logistic regression. Technically the constant load weight could be modeled as linear continuous variables for their linear intervals.

Line 178-183: Text may be removed because all the presented info is in Figure 1. Suggest that the authors simple describe the total sample size that met the inclusion criteria.

Table 1: Change “body height” to statue. Ad a footnote to define part-time. Recommend that the authors add % or mean to each variable because they are not very obvious. The scores of the job demands, control and social support have little clinical meaning. Suggest that the author change them to low and high using the medium cut-off point or Japanese stress standard in the literature for classifying the stress level. Then percentage of low or high level for each variable can be presented. Chi-square test can be further used for comparing pairs of the different levels of each variables. For example, the job control in female Group A may be different from Group B and C, but there is no difference between Groups B and C.

Line 209: Improper posture is not an academic term. Suggest that the authors use non-neutral posture if this is what it meant in the questionnaire. A larger number sounds better than a higher number. Suggest that the authors change the expression throughout the manuscript. Chang the section title to “Work characteristics”.

Line 228: Because the first episode of the LBP was recorded in a retrospective manner regardless of the length of recall time (i.e., could be one month or 10 years). It may be inappropriate to describe the reporting of LBP as simply prevalence. Consider using a revised term career-time cumulative prevalence of LBP.

Table 3 title is misleading because only the bottom three lines have the body weight percentage limit information. The reference group for each variable is different and nothing to do with the body weight limit. Table 3 needs to be revised to show proper comparisons. Similarly, Table 4 needs to be revised according to the above question.

Line 266: The statement “For percentages of body weight, the prevalence of severe LBP was lower in group B than in group C but higher than in group A. These associations were similar for the adjusted ORs of LBP.” May be the most important finding of the study. However, no discussion is provided for why the moderate load in term of body weight limit had the highest prevalence of LBP. The second paragraph in Discussion provides little interpretation of the results. It reads like results. The third paragraph discusses BMI, but the preceding paragraph (2nd) does not have BMI info. BMI data do support the argument. The higher BMI in Group B should be used for discussion.

Line 288: The sentence “This study showed that handling loads of 10 kg or more could not suppress severe LBP.” does not make sense. The following discussion shows mixed effect of lifted weight on the development of LBP. Both ISO and NIOSH use lifted load and postural information to determine the risk of LBP. It’s a scientific consensus that both are important lifting risk information. Using load alone is not a good risk estimate.

Reviewer #2: This study examined whether weight-based transport restrictions, which have been considered useful for the prevention of back pain in working people, are effective.

We consider your research method and the conclusions drawn to be valid and very significant.

The following comments should be reviewed and answered.

１）Abstract:

Gender representation is mixed in terms of Men/women and Male/Female. It would be better to unify them.

２）Basic information of workers

Duration of occupational engagement may influence the onset of low back pain. The authors should add to Basic information if possible.

３）Work description

　Line 220-221：「In the three groups, 82.7% of male and 86.0% of female workers had no or a small effect due to COVID-19 on their work」Data showing this statement is not included in the table 2, it would be better to add it.

**********

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.

Effect of relative weight limit set as a body weight percentage on work-related low back pain among workers

PONE-D-22-34000R1

Dear Dr. Iwakiri,

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,

Yee Guan Ng, Ph.D

Academic Editor

PLOS ONE

Additional Editor Comments (optional):

Dear Authors,

Thank you very much for your patience.

After a thorough review, your revised paper in addressing all the comments made by reviewers is recommended for publication to the Editorial Board.

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: 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

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: All comments are addressed appropriately. The statistical analysis was performed appropriately. The manuscript is presented clearly.

Reviewer #2: The authors have made appropriate corrections. No further amendments are required from me. This paper is well worth accepting.

**********

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

**********