Identification and assessment of a comprehensive set of structural factors associated with hospital costs in Switzerland

Michael M. Havranek; Josef Ondrej; Stella Bollmann; Philippe K. Widmer; Simon Spika; Stefan Boes

doi:10.1371/journal.pone.0264212

Peer Review History

Original SubmissionAugust 6, 2021
9 Nov 2021 Decision Letter - Matteo Lippi Bruni, Editor PONE-D-21-25093 Identification and assessment of a comprehensive set of structural factors associated with hospital costs in Switzerland PLOS ONE Dear Dr. Havranek, 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. While revising the paper, my recommendation is to follow closely the suggestions of both referees. One report provides rather detailed recommendations concerning the presentation of the material and suggesting a more precise phrasing of several paragraphs. They are mostly minor points, although some more effort to improve the interpretation of the results is required as well. The other report includes more fundamental critiques concerning the empirical strategy adopted in the analysis. In this respect, I expect the authors to strengthen the discussion concerning the motivation of their work and of the way the empirical study has been conducted. Please submit your revised manuscript by Dec 24 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, Matteo Lippi Bruni, PhD 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.pdf2. 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. 3. We note that you have indicated that data from this study are available upon request. PLOS only allows data to be available upon request if there are legal or ethical restrictions on sharing data publicly. For more information on unacceptable data access restrictions, please see http://journals.plos.org/plosone/s/data-availability#loc-unacceptable-data-access-restrictions. In your revised cover letter, please address the following prompts: a) If there are ethical or legal restrictions on sharing a de-identified data set, please explain them in detail (e.g., data contain potentially sensitive information, data are owned by a third-party organization, etc.) and who has imposed them (e.g., an ethics committee). Please also provide contact information for a data access committee, ethics committee, or other institutional body to which data requests may be sent. b) If there are no restrictions, please upload the minimal anonymized data set necessary to replicate your study findings as either Supporting Information files or to a stable, public repository and provide us with the relevant URLs, DOIs, or accession numbers. For a list of acceptable repositories, please see http://journals.plos.org/plosone/s/data-availability#loc-recommended-repositories. We will update your Data Availability statement on your behalf to reflect the information you provide. [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: 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: No ****** 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: The authors consider the relationship between case-mix adjusted cost and a range of hospital and regional characteristics in Switzerland. The analysis includes a principal component analysis, in recognition of the high degree of collinearity between groups of potentially relevant variables. The manuscript is presented in a convincing manner and represents a useful contribution. I recommend publication subject to some minor presentational changes. 1. When the authors refer to numbers larger than 1,000 in the text, they use a superscript comma “’” to separate thousands. A subscript comma “,” is more usual. 2. When referring to the unit of analysis, the authors use “on the hospital” or “on the patient” level. “at the hospital level” is what I think is meant. 3. In discussing descriptive results, the authors list mean, standard deviation and range of costs per patient as part of text. This information would be easier to read in Table 2, where a set of other variables are already provided. 4. In Table 2, the authors present a single row for each type of hospital. An additional row, containing the same information across all hospitals together would also be useful. Further, it would add to transparency if equivalent information to that presented in Table 2 was made available for all variables. An appendix or supplementary material would be sufficient for this. 5. In Table 3, V6 (Rate of residents to patients) could be made more informative by rescaling. It should also be noted why some observations are missing for this variable. 6. The two heat maps are difficult to read, most likely due to low resolution. 7. In the Discussion section, case-mix adjustment is referred to as complete. A less absolute term such as considerable would be more defendable. 8. At several points in the Discussion, the authors refer to the issue of up front costs related to skills. It is not clear why differences in the skills of staff would not be covered by wages and so are not up front but regular expenditures. A distinction should be drawn between this and capital investments, which do represent an upfront cost that regular DRG payments don’t capture well. 9. Broadly the authors draw a connection between high costs and insufficient compensation from the DRG system. I agree with this conclusion as an interpretation of the results but it would be useful to remove potential ambiguity by arguing that higher case-mix adjusted costs reflect insufficient compensation nfrom the DRG system. Reviewer #2: The Authors present a study to integrate and extend previous findings by identifying and assessing various organizational and regional factors that explain systematic cost variations across Swiss hospitals. The aim of the paper is to define a comprehensive set of variables that can be used to distinguish hospitals regarding different cost-related aspects. The Authors claim that to achieve this, they examine 23 hospital indicators and investigated how these indicators are associated with each other and with different hospital types. I find the idea interesting but I am not convinced by this work. In fact, I am rather surprised by the methodology used: with such data, the Authors could have estimates a causal relationship between the indicators and the hospital costs, instead of performing Pearson correlations, a principal component analysis (PCA) and an analysis of variance (ANOVA). Another relevant issue is related to policy implications. From a policy maker's perspective, why is it be relevant to know the effects of 23 cost predictors on hospital costs? Last, section 5 "discussion" is mostly a repetition of section 4 "results". ****** 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: Yes:** James Gaughan 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. https://doi.org/10.1371/journal.pone.0264212.r001
Revision 1
31 Jan 2022 Author Response Response to each point raised by the reviewers Reviewer # 1: 1. When the authors refer to numbers larger than 1,000 in the text, they use a superscript comma “’” to separate thousands. A subscript comma “,” is more usual. Thanks for this suggestion, we have replaced “’” by “,” throughout the text. 2. When referring to the unit of analysis, the authors use “on the hospital” or “on the patient” level. “at the hospital level” is what I think is meant. Yes, you are right, this has been adapted as well. 3. In discussing descriptive results, the authors list mean, standard deviation and range of costs per patient as part of text. This information would be easier to read in Table 2, where a set of other variables are already provided. Good point, we have now added a Table 2a depicting mean, standard deviation, and range of costs that were previously included in the main text. 4. In Table 2, the authors present a single row for each type of hospital. An additional row, containing the same information across all hospitals together would also be useful. Further, it would add to transparency if equivalent information to that presented in Table 2 was made available for all variables. An appendix or supplementary material would be sufficient for this. We agree with both points. An additional row informing about aggregate values across all hospitals is part of Table 2b now and an additional table informing about the other variables has been added to the appendix. 5. In Table 3, V6 (Rate of residents to patients) could be made more informative by rescaling. It should also be noted why some observations are missing for this variable. Thanks, the rescaling has been done and the information about the reason for the missing values has been provided. 6. The two heat maps are difficult to read, most likely due to low resolution. The low resolution of the heat maps seems to occur when the PDF is produced for review in the submission process of PLOS. Both figures actually have a much higher resolution and have passed the PACE digital diagnostic requirements. We will make sure that this issue is resolved together with PLOS before publication. Thanks for pointing it out. 7. In the Discussion section, case-mix adjustment is referred to as complete. A less absolute term such as considerable would be more defendable. Thanks, this has been changed. 8. At several points in the Discussion, the authors refer to the issue of upfront costs related to skills. It is not clear why differences in the skills of staff would not be covered by wages and so are not up front but regular expenditures. A distinction should be drawn between this and capital investments, which do represent an upfront cost that regular DRG payments don’t capture well. Yes, you are right, we have divided these two separate aspects into “salary levels” and “upfront capital investments” now, as you have proposed. However, it must be noted that both aspects are currently not sufficiently compensated by the Swiss DRG system. Because of this, we included both aspects in our discussion. 9. Broadly the authors draw a connection between high costs and insufficient compensation from the DRG system. I agree with this conclusion as an interpretation of the results, but it would be useful to remove potential ambiguity by arguing that higher case-mix adjusted costs reflect insufficient compensation from the DRG system. That’s a good idea, we have added this to the beginning of the discussion section. Reviewer # 2: 1a. I am rather surprised by the methodology used: with such data, the Authors could have estimated a causal relationship between the indicators and the hospital costs, instead of performing Pearson correlations, a principal component analysis (PCA) and an analysis of variance (ANOVA). 1b. From a policy maker's perspective, why is it relevant to know the effects of 23 cost predictors on hospital costs? Thanks for your suggestions and your question, we understand your perspective and would like to give you some more background on why we chose our methodology: Previous research in Switzerland has only discussed certain specific structural factors that are related to cost differences between hospitals separately. Based on that, there have been propositions for exogenous factors that should be included in cost benchmarking and reimbursement (see references below). However, these propositions lacked transparency on why they selected exactly those specific factors for inclusion and on what other relevant factors would have existed. Thus, we aimed to identify and assess a broad set of exogenous cost-related variables in a comprehensive and transparent manner. Our results shall serve as a foundation for objectifying future discussions in Switzerland about which factors exist and which of these should be included in cost benchmarking and reimbursement. The presented relationships shall inform policy-makers about which structural influences on hospitals are not sufficiently compensated by the Swiss DRG system. Furthermore, it shall support them in selecting and combining several specific variables to systematically compensate hospitals for these uncontrollable organizational and regional influences. Now regarding the estimation of causal relationships between the indicators and the hospitals costs: We assume you are referring to regression analyses, right? On the one hand, we did not present regressions because this was not the focus of our paper based on the motivation outlined above. On the other hand, we were faced with the practical problem that the identified variables were highly collinear, which led to multiple issues of multicollinearity when estimating regressions. The next practical steps in Switzerland must now lie in determining how the identified structural differences among hospitals should be selected and combined to compensate hospitals for uncontrollable organizational and regional differences. For this, we suggest a regression-based approach, which selects a limited number of independent variables by building on the findings presented herein. We have now also tried to clarify our motivation and the added value of our study in the manuscript. However, we deliberately avoided to go into too much detail about the current specific situation in Switzerland, because the publication is directed towards an international readership. We hope that we were able to clarify these points for you. - Einkaufsgemeinschaft HSK. Benchmark SwissDRG Tarifjahr 2021. HSK; 2020. - Widmer P, Trottmann M, Telser H. Das Fallpauschalenmodell: Leistungsbezogene Basispreise unter SwissDRG. Polynomics; 2015 2. Last, section 5 "discussion" is mostly a repetition of section 4 "results". Yes, you are right, there are some repetitions in the discussion section. We have now deleted some of them to make it less repetitive. However, we believe that some other repetitions should remain, because they make our deliberations during the discussion easier to follow. . Attachments Attachment Submitted filename: Rebuttal_Letter_PLOS_ONE_MH.docx https://doi.org/10.1371/journal.pone.0264212.r002
7 Feb 2022 Decision Letter - Matteo Lippi Bruni, Editor Identification and assessment of a comprehensive set of structural factors associated with hospital costs in Switzerland PONE-D-21-25093R1 Dear Dr. Havranek, 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, Matteo Lippi Bruni, PhD Academic Editor PLOS ONE Additional Editor Comments (optional): Reviewers' comments: https://doi.org/10.1371/journal.pone.0264212.r003
Formally Accepted
8 Feb 2022 Acceptance Letter - Matteo Lippi Bruni, Editor PONE-D-21-25093R1 Identification and assessment of a comprehensive set of structural factors associated with hospital costs in Switzerland Dear Dr. Havranek: I'm pleased to inform you that your manuscript has been deemed suitable for publication in PLOS ONE. Congratulations! Your manuscript is now with our production department. If your institution or institutions have a press office, please let them know about your upcoming paper now to help maximize its impact. If they'll be preparing press materials, please inform our press team within the next 48 hours. 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. If we can help with anything else, please email us at plosone@plos.org. Thank you for submitting your work to PLOS ONE and supporting open access. Kind regards, PLOS ONE Editorial Office Staff on behalf of Dr. Matteo Lippi Bruni Academic Editor PLOS ONE https://doi.org/10.1371/journal.pone.0264212.r004

Open letter on the publication of peer review reports

PLOS recognizes the benefits of transparency in the peer review process. Therefore, we enable the publication of all of the content of peer review and author responses alongside final, published articles. Reviewers remain anonymous, unless they choose to reveal their names.

We encourage other journals to join us in this initiative. We hope that our action inspires the community, including researchers, research funders, and research institutions, to recognize the benefits of published peer review reports for all parts of the research system.

Learn more at ASAPbio .