PONE-D-21-19512

Direct medical costs after surgical or nonsurgical treatment for degenerative lumbar spinal disease: a nationwide matched cohort study with a 10-year follow-up

PLOS ONE

Dear Dr. Chung,

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.

I would be happy to entertain a revision if you can adequately address the reviewers' comments.

Please submit your revised manuscript by Aug 19 2021 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.

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We look forward to receiving your revised manuscript.

Kind regards,

Dean Chou, MD

Academic Editor

PLOS ONE

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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

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

Reviewer #1: Yes

Reviewer #2: Yes

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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: No

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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

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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: This study reviews the cost of surgical versus non-surgical intervention on lumbar degenerative spine pathology in a national database. The authors utilize Korea’s national health insurance data repository to evaluate fee for service charges. The authors find that, while surgery is initially more expensive, the results even out over years.

The manuscript offers good analysis of a national insurance database. It is certainly novel, and the results likely warrant publication. However, there are some issues.

When matching patients, the authors use age, sex, diagnosis and the presence of osteoporosis and diabetes as variables. The authors don’t give a rationale for these comorbidities. They leave out several important comorbidities (for example, smoking status, hypertension, CHF, etc). Furthermore, while it may not be available in their database, some sort of socioeconomic matching variable would be beneficial (insurance carrier, income, employment status, etc). At the very least, further explanation of their process for arriving at the matching variables is needed.

When matching the patients, are the costs over the last three years just regarding their spinal pathology or all medical costs?

The description of the “non-surgery” cohort as the “intervention” cohort is confusing. Why did the authors choose this label instead of something like “nonsurgical” or “conservative management?”

The authors do mention this, but it is worth reiterating: the costs here do not account for societal costs such as missed work and quality of life.

Lastly, the authors use charges reported to a national insurance database as a surrogate for costs here. This is a major point and warrants significant discussion. Charges are not a surrogate for costs, at least in the American system to which I am familiar. I highly doubt they are in Korea, either. The cost of a procedure or service indicates how much the provider must spend to provide that service, such as infrastructure, salaries, medications, and supplies.

Readers of this manuscript are likely going to be unfamiliar with the Korean medical financing system, so the authors should briefly explain this. If the hospitals are private entities, what constraints do they have on their charges? How do they determine the charge for a procedure or visit? How closely do the authors believe the charges represent the true cost of providing a procedure or visit? If they are freely set by the private institutions and responsive to market pressures, they are likely a good approximation. If they are set by the government or some planning body, they are unlikely to actually represent costs. The manuscript would benefit greatly from the authors both giving a brief explanation of the Korean healthcare financing system and of discussing how this would affect the relationship of charges to costs for this study.

Reviewer #2: This is an interesting study especially with long follow-up up to 10 years. Several issues that need to be addressed include the following:

- The cost of non-surgical management varies across countries and that contributes significantly to the data presentation.

- The extent of patients identified as disabled who did not return to work needs to be analyzed because the indirect cost of a leave of absence can offset some of the early costs of surgery.

- The reoperation rate was especially high in the surgical group, necessitating better clarification/stratification of this data for interpretation.

- Figure 2 and tables are unclear and needs better organization and clarification.

- State the percentage of patients who had long term follow.

- Determine the number of patients at each follow-up point.

- The quality of life and disability index score such as ODI would be helpful to better compare both groups.

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Reviewer #1: Yes: Anthony DiGiorgio

Reviewer #2: No

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PONE-D-21-19512R1Direct medical costs after surgical or nonsurgical treatment for degenerative lumbar spinal disease: a nationwide matched cohort study with a 10-year follow-upPLOS ONE

Dear Dr. Chung,

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 address reviewer #1's comments.

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

Please submit your revised manuscript by Dec 05 2021 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,

Dean Chou, MD

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.

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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: (No Response)

Reviewer #2: All comments have been addressed

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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: Partly

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: No

**********

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: The authors have done an outstanding job addressing most of my previous concerns. My one lasting issue is with the discussion of “cost” versus “charges.” The authors have included an excellent overview of the Korean healthcare financing system. I applaud them for that. From the author’s explanation, the costs they report are based on a centrally set reimbursement fee by the Korean government. Thus, they don’t represent true costs. They state in their response to my comment that the “cost” of medical services and supplies is determined by the board of the NHIS. A more accurate description would be that the “reimbursement” is determined by the board of NHIS. This is similar to the United States. The government may set a reimbursement for a surgical procedure, but that reimbursement is not reflective of the true cost. The administrators who set that rate may try to approximate cost, but costs are ever shifting and determined by the market. If, for example, the cost of labor increases (as has happened recently), the costs of surgical procedures will increase. However, the reimbursement rate from the government will remain the same, regardless of how much the hospital must pay out for staffing, electricity, supplies, etc. True determination of cost requires a thorough accounting including time-driven activity-based costing, which is far outside the scope of this paper.

While these economic nuances need not be included in this particular manuscript, we should ensure that the conversation around surgical costs is appropriately phrased. For example, in the conclusion, instead of stating “surgery was initially more costly,” it would be more appropriate to say “surgical treatment initially led to more government reimbursement than nonsurgical…” or “cost the government payor more…” or something along those lines. The authors should ensure that the language in the paper does not suggest that the monetary figures are implied to be actual economic costs but instead reflect reimbursement charges from the government.

Reviewer #2: (No Response)

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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: Yes: Anthony M DiGiorgio, DO, MHA

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.

Direct medical costs after surgical or nonsurgical treatment for degenerative lumbar spinal disease: a nationwide matched cohort study with a 10-year follow-up

PONE-D-21-19512R2

Dear Dr. Chung,

Congratulations!  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.

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Kind regards,

Dean Chou, MD

Academic Editor

PLOS ONE

Additional Editor Comments (optional):

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: The authors have done an outstanding job updating the manuscript. I have no further comments.

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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: Yes: Anthony DiGiorgio