Endothelial dysfunction in ME/CFS patients

Miriam Kristine Sandvik; Kari Sørland; Elisabeth Leirgul; Ingrid Gurvin Rekeland; Christina Særsten Stavland; Olav Mella; Øystein Fluge

doi:10.1371/journal.pone.0280942

Peer Review History

Original SubmissionJuly 5, 2022
15 Sep 2022 Decision Letter - Debora Walker, Editor PONE-D-22-19007Endothelial dysfunction in ME/CFS patients.PLOS ONE Dear Dr. Sandvik, 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. The reviewer report can be found at the end of this email. Please note that we have only been able to secure a single reviewer to assess your manuscript. We are issuing a decision on your manuscript at this point to prevent further delays in the evaluation of your manuscript. Please be aware that the editor who handles your revised manuscript might find it necessary to invite additional reviewers to assess this work once the revised manuscript is submitted. However, we will aim to proceed on the basis of this single review if possible. 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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: No ******** 2. Has the statistical analysis been performed appropriately and rigorously? Reviewer #1: No ****** 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. 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This is a study of vessel endothelial function in patients with Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS). Two main outcomes (flow-mediated dilation, FMD, and post-occlusive reactive hyperemia, PORH) and supplementary measures of symptom severity and physical functioning have been measured at baseline and after 18 months of treatment in 39 patients and compared with healthy controls. The study seems well designed and the research questions are clearly stated. However, there are some important points that need further clarification: see the specific issues below. SPECIFIC ISSUES. 1. Lines 136-138 say that the severity of ME/CFS has been categorized according to self-reported function level and the physicians’ evaluation at the time of inclusion. However, nothing is said about how these different sources of information were combined. The authors should provide a detailed description of the protocol used to define the severity classes. 2. Lines 202-204 say that some variables were not normally distributed, without specifying which variables. This creates some confusion. For example, some variables are first analyzed by ANCOVA methods (Table 2), which require normality, and then examined by the the Wilcoxon’s test (Table 3), as they were non-normal. The authors should specify which variables are normally distributed and the test used to check normality. 3. Lines 205-208 say that general linear models (GLM) for repeated measures were used to assess differences in changes of the outcomes measures (FMD or PORH), from baseline to 18 months, between the randomization groups (rituximab and placebo). Although this approach is in principle correct, I was not able to understand the structure of the model, because the outcome of this analysis is displayed only by a battery of pictures. I'd welcome a traditional table with the estimates (and p-values) of the coefficients of the model, including an estimate of the heterogeneity parameter (the variance of the random effects). ****** 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 ******** [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". 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Revision 1
31 Oct 2022 Author Response Response to reviewers regarding the article "Endothelial dysfunction in ME/CFS patients" (PONE-D-22-19007) We want to thank the reviewer and the editors for the positive evaluation of our manuscript, and for their valuable comments. We will respond to the comments made by the reviewer and the additional comments by the editors point by point, as requested (all references to manuscript text refer to the version with marked changes): Reviewer #1: SPECIFIC ISSUES. 1. Lines 136-138 say that the severity of ME/CFS has been categorized according to self-reported function level and the physicians’ evaluation at the time of inclusion. However, nothing is said about how these different sources of information were combined. The authors should provide a detailed description of the protocol used to define the severity classes. Answer: We agree that our description of the severity categories are insufficient. We have added this text: (lines 142-145): “The categorization into different severity groups was based on thorough clinical assessment by the physician at the time of inclusion, and supported by patient-reported function level and questionnaires.» The following list was used as a guideline for the clinicians (originally in Norwegian, translated here): • Severe ME/CFS often has a 5-10% function level. • Moderate/severe ME/CFS often has an 8-10-13% function level. • Moderate ME/CFS often has a 12-15-18% function level. • Mild/moderate ME/CFS often has an 18-25% function level. • Mild ME/CFS often has a 25-40% function level. • Very severe ME/CFS is typically < 5%, and should not be included in the RituxME study We also submit the trial protocol as supplementary material (S1 File). 2. Lines 202-204 say that some variables were not normally distributed, without specifying which variables. This creates some confusion. For example, some variables are first analyzed by ANCOVA methods (Table 2), which require normality, and then examined by the Wilcoxon’s test (Table 3), as they were non-normal. The authors should specify which variables are normally distributed and the test used to check normality. Answer: We agree with the reviewer that the description of our choice of analyses were unclear. All variables have been tested for normality using the Shapiro-Wilk´s test. For the vascular variables, FMD was normally distributed in both patients and controls, while PORH was normally distributed in patients, but not in the control group. The patient variables Fatigue Severity Scale, self-reported function level, SF-36 Physical Function and Steps per 24 h were not normally distributed. We have specified and explained our choices of statistical tests more thoroughly in the "Statistical analyses" section (lines 207-223 and 229-233) and in the tables, and hope this is satisfactory. We have, also, reanalyzed the correlation analyses including PORH measurements with non-parametric tests, and made corresponding changes in the "Results" section (lines 295, 297 and 309-315). The figures have been adjusted with p-values from the appropriate analyses, and with error bars corresponding to the type of analyses (mean, SD for normally distributed data, and median, IQR for data not normally distributed). 3. Lines 205-208 say that general linear models (GLM) for repeated measures were used to assess differences in changes of the outcomes measures (FMD or PORH), from baseline to 18 months, between the randomization groups (rituximab and placebo). Although this approach is in principle correct, I was not able to understand the structure of the model, because the outcome of this analysis is displayed only by a battery of pictures. I'd welcome a traditional table with the estimates (and p-values) of the coefficients of the model, including an estimate of the heterogeneity parameter (the variance of the random effects). Answer: We have included the analysis syntax for the GLM repeated measures as a supporting file (S2 File), which should give the details of the model. We also added in the Figure 3 the differences with confidence intervals between groups, for FMD og PORH. Additional requirements by the editors: 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. Answer: We have made changes in the manuscript to meet PLOS ONE´s style requirements. These changes are not marked in the manuscript with marked changes. 2. Please provide additional details regarding participant consent. In the ethics statement in the Methods and online submission information, please ensure that you have specified (1) whether consent was informed and (2) what type you obtained (for instance, written or verbal, and if verbal, how it was documented and witnessed). If your study included minors, state whether you obtained consent from parents or guardians. If the need for consent was waived by the ethics committee, please include this information. If you are reporting a retrospective study of medical records or archived samples, please ensure that you have discussed whether all data were fully anonymized before you accessed them and/or whether the IRB or ethics committee waived the requirement for informed consent. If patients provided informed written consent to have data from their medical records used in research, please include this information. Answer: We have added a section on participant consent in the Methods section (lines 127-132). 3. We note that the grant information you provided in the ‘Funding Information’ and ‘Financial Disclosure’ sections do not match. When you resubmit, please ensure that you provide the correct grant numbers for the awards you received for your study in the ‘Funding Information’ section. Answer: We thank the editors for pointing this out – the discrepancies may be due to different translations of funding organizations. We have corrected the information in the "Funding information" section at resubmission. 4. 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 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 identifying or sensitive patient information) 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. Please see http://www.bmj.com/content/340/bmj.c181.long for guidelines on how to de-identify and prepare clinical data for publication. 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. Answer: After re-evaluation, we find that it is acceptable to make an anonymized datafile available, and have submitted this as supplementary information (S3 File for patients and PORH controls, S4 File for patients and FMD controls). 5. We note that you have stated that you will provide repository information for your data at acceptance. Should your manuscript be accepted for publication, we will hold it until you provide the relevant accession numbers or DOIs necessary to access your data. If you wish to make changes to your Data Availability statement, please describe these changes in your cover letter and we will update your Data Availability statement to reflect the information you provide. Answer: We refer to our answer above regarding data availability. 6. We note that you have included the phrase “data not published” in your manuscript. Unfortunately, this does not meet our data sharing requirements. PLOS does not permit references to inaccessible data. We require that authors provide all relevant data within the paper, Supporting Information files, or in an acceptable, public repository. Please add a citation to support this phrase or upload the data that corresponds with these findings to a stable repository (such as Figshare or Dryad) and provide and URLs, DOIs, or accession numbers that may be used to access these data. Or, if the data are not a core part of the research being presented in your study, we ask that you remove the phrase that refers to these data. Answer: We have deleted two references to unpublished data/observations in lines 82-85 and lines 438-440. We have kept a brief description of exploratory FMD measures from 2014 ( lines 85-91) because these findings were relevant in the planning of the substudy described in this paper. We do not have the participants´ consent to make these raw data available in a supplementary file. If the editors find this unsatisfactory, we suggest to delete all mention of these exploratory measures (lines 85-91). 7. Please include a separate caption for each figure in your manuscript. Answer: We have included a caption for each figure as requested. In addition to the changes made upon request, we suggest to delete correlations between vascular measures and disease severity at 18 months, lines 316-319. We also made some minor changes in wording and grammar throughout the text, those changes are marked in the manuscript with marked changes, but not referenced in detail here. Attachments Attachment Submitted filename: Response to reviewers.docx https://doi.org/10.1371/journal.pone.0280942.r002
12 Jan 2023 Decision Letter - Doan TM Ngo, Editor Endothelial dysfunction in ME/CFS patients. PONE-D-22-19007R1 Dear Dr. Sandvik, 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, Doan TM Ngo, B.Pharm., PhD. 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: (No Response) ****** 3. Has the statistical analysis been performed appropriately and rigorously? Reviewer #1: (No Response) ****** 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: (No Response) ****** 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: (No Response) ****** 6. Review Comments to the Author Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters) Reviewer #1: (No Response) ****** 7. PLOS authors have the option to publish the peer review history of their article (what does this mean?). If published, this will include your full peer review and any attached files. If you choose “no”, your identity will remain anonymous but your review may still be made public. Do you want your identity to be public for this peer review? For information about this choice, including consent withdrawal, please see our Privacy Policy. Reviewer #1: No ******** https://doi.org/10.1371/journal.pone.0280942.r003
Formally Accepted
25 Jan 2023 Acceptance Letter - Doan TM Ngo, Editor PONE-D-22-19007R1 Endothelial dysfunction in ME/CFS patients Dear Dr. Sandvik: 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. Doan TM Ngo Academic Editor PLOS ONE https://doi.org/10.1371/journal.pone.0280942.r004

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