Comparison of lean mass indices as predictors of mortality in incident peritoneal dialysis patients

Seok Hui Kang; A. Young Kim; Jun Young Do

doi:10.1371/journal.pone.0254942

Peer Review History

Original SubmissionMarch 26, 2021
4 May 2021 Decision Letter - Pasqual Barretti, Editor PONE-D-21-09966 Comparison of lean mass indices as predictors of mortality in incident peritoneal dialysis patients PLOS ONE Dear Dr. Young Do 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 3 weeks. 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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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. We note that the abstract of your article may have been presented elsewhere. At this time, please clarify whether your abstract was previously published, and whether it was peer-reviewed. If previously published, please provide a link to the full text of the abstract or a PDF copy and clarify the copyright permissions on the published work. 3. Thank you for providing the date(s) when patient medical information was initially recorded. Please also include the date(s) on which your research team accessed the databases/records to obtain the retrospective data used in your study. 4. Please provide the name of the institution where participants were from. Additional Editor Comments: Both authors have raised important questions, which must be addressed by the authors. According to my point of view, those questions are easy to address, as well as the suggestions were made. The reviewer 1 have emphasized statistical and methodological aspects, in special on censored patients and competitive risks to outcomes. The reviewer 2 have made important questions about nutritional aspects. [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: No 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: 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: Dear editor and authors, I carefully reviewed the manuscript entitled “Comparison of lean mass indices as predictors of mortality in incident peritoneal dialysis patients”. My comments and concerns are the following: The research question is interesting, and the manuscript well written in a standard technical English. The rationale of the study is well elaborated but I suggest to change the information that DEXA is commonly used because the low access of most centers to this technology. Instead, I’d use DEXA is a reliable tool indicated to … or is commonly used in science to predict … Almost 25% of the study population were excluded because they didn’t have a DEXA measurement. It is important to characterize these individuals in comparison to the population included to facilitate the analysis of any potential selection bias. The authors should include in their limitation the albumin measured with bromocresol green instead of purple. Censoring in dialysis studies is key for interpretation of survival analysis. As performed in current studies there is a risk that competing events may have influenced the final results and interpretation. So, two recommendations: first make available the absolute number of patients who were censored and the reasons for censoring; and perform a competing risk analysis considering as censored only patients active at the end of follow-up and the remaining as a competing event. The study design (retrospective) should be described also in the methods and not only in the paragraph of limitations. Reviewer #2: Review comments to the author The authors performed a retrospective observational analysis to determine clinical variables (using various adjusted indices) as predictors of mortality in incident peritoneal dialysis. There are some recommendations that might be useful to consider: a) In the introduction, the authors discuss in a more emphasized way about the ALM, which is not the main result of this study. The main result of this study is not highlighted. It's important to talk about LTLM. b) In the methods, the authors need to clarify the study design. c) About evaluations: - Were all evaluations performed at the same time or was there a time between them? (DXA, BIS, echocardiography, anthropometry and laboratory evaluation). d) The text contains many abbreviations. eliminate some in order to make reading more comfortable. e) the discussion answers many questions about the study, however, it seems confusing at times. Review is needed. ****** 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. https://doi.org/10.1371/journal.pone.0254942.r001
Revision 1
28 May 2021 Author Response Additional Editor Comments: Both authors have raised important questions, which must be addressed by the authors. According to my point of view, those questions are easy to address, as well as the suggestions were made. The reviewer 1 have emphasized statistical and methodological aspects, in special on censored patients and competitive risks to outcomes. The reviewer 2 have made important questions about nutritional aspects. Answer: Thank you for your comments regarding our manuscript. We have incorporated the reviewers’ suggestions into the revised manuscript and indicated them in red font. We have responded to the reviewers’ comments. We hope that all issues have been adequately addressed and that the manuscript is now acceptable for publication. Reviewer #1: Dear editor and authors, I carefully reviewed the manuscript entitled “Comparison of lean mass indices as predictors of mortality in incident peritoneal dialysis patients”. My comments and concerns are the following: The research question is interesting, and the manuscript well written in a standard technical English. The rationale of the study is well elaborated but I suggest to change the information that DEXA is commonly used because the low access of most centers to this technology. Instead, I’d use DEXA is a reliable tool indicated to … or is commonly used in science to predict … Answer: Thank you for your comments. We have revised the relevant line as follows: Dual X-ray absorptiometry (DXA) is a reliable tool used to predict the muscle mass. Almost 25% of the study population were excluded because they didn’t have a DEXA measurement. It is important to characterize these individuals in comparison to the population included to facilitate the analysis of any potential selection bias. Answer: We agree with the reviewer’s comments. Exclusion of 23.9% of the participants could be associated with a selection bias. We compared the two cohorts (included vs. excluded participants), but there were no significant differences in the baseline characteristics. These results can be helpful in attenuating the selection bias by the exclusion of participants. We have added these comments in the Limitation section and Table S1 for comparison between the included and excluded participants. The authors should include in their limitation the albumin measured with bromocresol green instead of purple. Answer: As the reviewer pointed out, serum albumin measurements using bromocresol green is associated with non-specific binding and a proportional bias among the two colorimetric and immunologic methods has been reported [1]. A previous study showed that the bromocresol green method led to a mean bias of 0.62 g/dL compared to the immunologic method, which resulted in an inappropriate treatment decision for 59% of patients with hypoalbuminemia [2]. Although bromocresol green is a classical method for predicting serum albumin level, the use of bromocresol purple or immunologic method should be preferred to measure the serum albumin level, to avoid overestimation in patients with risk of malnutrition. We have added these comments and references in the Limitation section. Added reference [1] Alcorta MD, Alvarez PC, Cabetas RN, Martín MA, Valero M, Candela CG. The importance of serum albumin determination method to classify patients based on nutritional status. Clin Nutr ESPEN. 2018 Jun;25:110-113. [2] van de Logt AE, Rijpma SR, Vink CH, Prudon-Rosmulder E, Wetzels JF, van Berkel M. The bias between different albumin assays may affect clinical decision-making. Kidney Int. 2019 Jun;95(6):1514-1517. Censoring in dialysis studies is key for interpretation of survival analysis. As performed in current studies there is a risk that competing events may have influenced the final results and interpretation. So, two recommendations: first make available the absolute number of patients who were censored and the reasons for censoring; and perform a competing risk analysis considering as censored only patients active at the end of follow-up and the remaining as a competing event. Answer: Thank you for your comment. In our study, the number of participants who survived, died, or were censored at the end-point of the follow-up were 152, 209, and 167, respectively. Among the censored patients, the cause of censoring was as follows: 91 patients were transferred for hemodialysis (54.5%); 51 for kidney transplantation (30.5%); 22 were transferred to other hospitals (13.2%); and 3 had recovery of their renal function (1.8%). We defined censored cases as competing risk and performed Fine and Gray competing risk model with cohorts without censoring. Results from competing risk model were similar with those from the total cohort. We have added these comments and Table S2 in the Methods and Results sections. The study design (retrospective) should be described also in the methods and not only in the paragraph of limitations. Answer: Thank you for your comment. We have indicated “retrospective observational study” in the Methods section. Reviewer #2: Review comments to the author The authors performed a retrospective observational analysis to determine clinical variables (using various adjusted indices) as predictors of mortality in incident peritoneal dialysis. There are some recommendations that might be useful to consider: a) In the introduction, the authors discuss in a more emphasized way about the ALM, which is not the main result of this study. The main result of this study is not highlighted. It's important to talk about LTLM. Answer: Thank you for your comments. We have added some comments regarding the LTLM ratio in the Introduction section and transferred some comments from the Discussion section to Introduction. The following comments have been added: The limb/trunk lean mass (LTLM) ratio was first reported by Kato et al. as a nutritional and prognostic indicator in hemodialysis patients [1]. Lean mass can be associated with over-hydration when measured using DXA, but the ratio using lean limb mass and trunk lean mass would attenuate the effect of over-hydration. In addition, malnourished individuals, such as PD patients, have increased protein catabolism in the extremities earlier than in the viscera [2]. These may reveal that LTLM ratio can be an option for predicting clinical outcomes in PD patients compared to classic lean mass indices. Reference [1] Kato A, Odamaki M, Yamamoto T, Yonemura K, Maruyama Y, Kumagai H, et al. Influence of body composition on 5 year mortality in patients on regular haemodialysis. Nephrol Dial Transplant 2003;18:333-340. [2] Heymsfield SB, McManus C, Stevens V, Smith J. Muscle mass: reliable indicator of protein-energy malnutrition severity and outcome. Am J Clin Nutr. 1982 May;35(5 Suppl):1192-1199. b) In the methods, the authors need to clarify the study design. Answer: Thank you for your comments. We have indicated “retrospective observational study” in the Methods section. c) About evaluations: - Were all evaluations performed at the same time or was there a time between them? (DXA, BIS, echocardiography, anthropometry and laboratory evaluation). Answer: Thank you for your comment. All laboratory studies, anthropometry, DXA, and bioimpedance analysis measurements, included in this study, were performed on the same day. We have added the comment in the Method section. d) The text contains many abbreviations. eliminate some in order to make reading more comfortable. Answer: Thank you for your comment. We have replaced some abbreviations with their full name throughout the manuscript. e) the discussion answers many questions about the study, however, it seems confusing at times. Review is needed. Answer: Thank you for your comment. We have condensed the Discussion section. Part of the discussion which were repeated or were similar have been merged. We have also deleted redundant or unnecessary portions, such as difference between bioimpedance spectroscopy and bioimpedance analysis. Attachments Attachment Submitted filename: Responses for reviewers comments-final.docx https://doi.org/10.1371/journal.pone.0254942.r002
7 Jul 2021 Decision Letter - Pasqual Barretti, Editor Comparison of lean mass indices as predictors of mortality in incident peritoneal dialysis patients PONE-D-21-09966R1 Dear Dr. Jung Young Do 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. 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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: Dear editor/authors, All my comments, critics and suggestions were properly addressed improving the final quality of the manuscript. I have no further comments Reviewer #2: The authors have adequately addressed all comments raised in the review and it is acceptable for publication. ****** 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:** Thyago Proenca de Moraes Reviewer #2: No https://doi.org/10.1371/journal.pone.0254942.r003
Formally Accepted
13 Jul 2021 Acceptance Letter - Pasqual Barretti, Editor PONE-D-21-09966R1 Comparison of lean mass indices as predictors of mortality in incident peritoneal dialysis patients Dear Dr. Do: 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 Prof. Pasqual Barretti Academic Editor PLOS ONE https://doi.org/10.1371/journal.pone.0254942.r004

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