Comparison of devices used to measure blood pressure, grip strength and lung function: A randomised cross-over study

Carli Lessof; Rachel Cooper; Andrew Wong; Rebecca Bendayan; Rishi Caleyachetty; Hayley Cheshire; Theodore Cosco; Ahmed Elhakeem; Anna L. Hansell; Aradhna Kaushal; Diana Kuh; David Martin; Cosetta Minelli; Stella Muthuri; Maria Popham; Seif O. Shaheen; Patrick Sturgis; Rebecca Hardy

doi:10.1371/journal.pone.0289052

Peer Review History

Original SubmissionNovember 21, 2022
2 Feb 2023 Decision Letter - Masaki Mogi, Editor PONE-D-22-31125Comparison of devices used to measure blood pressure, grip strength and lung function: a randomised cross-over studyPLOS ONE Dear Dr. Hardy, 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 manuscript is well assessed by the two reviewers; however, several major critiques are raised in the present form. Read the suggestions carefully and respond to them appripriately. Please submit your revised manuscript by Mar 19 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. 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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: Yes 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: Carli Lessof et al. used a randomized cross-over study to compare different devices for their measurement of blood pressure, grip strength and lung function. All the measurements and analyses were performed to a good technical standard. Measurement differences between devices are bound to exist, however, the article does not provide information for us to choose a better device. I recommend comparing these devices to standard devices such as mercury sphygmomanometer. Reviewer #2: Review of PONE-D-22-31125 Thank you for the invitation to review the manuscript “Comparison of devices used to measure blood pressure, grip strength and lung function: a randomised cross-over study”. The manuscript is well-written, and the research question is clearly defined. The study is scientifically sound, and I have no significant concerns. I therefore provide only minor comments and suggestions which I hope the authors will find useful in improving the presentation of their work. Abstract It would be useful to state that multiple measurements were taken for each device. L58: consider providing quantitative estimates with the statement that “differences were small”, for example the range of mean differences. Key implications of the findings for statistical analyses could be more specific, addressing how these findings should be considered when “modelling intra-individual changes in function and when carrying out cross-study analyses.” Introduction A brief paragraph discussing the test-retest reliability of these devices would be useful to contextualise the findings regarding difference between devices. How do measurements taken with the same device vary in magnitude compared to differences between devices? L89-91: could these differences instead be accounted for in the analyses? It would be useful if the authors would be more specific about what they mean by “in some instances”. L94: although the authors cite multiple studies, they state that the “evidence is limited”. L98 (and elsewhere): I suggest avoiding unnecessary acronyms such as “BP” for blood pressure. Methods L104: consider providing the name of the guidelines (CONSORT) here. L109: “and the South East” of England. L119: “anonymised” -> “pseudo anonymised”. Please provide the justification/rationale for using a randomised cross-over study design. This might seem obvious, but it is useful to state this explicitly in the text. As noted above, it would be useful to state earlier that multiple measurements were taken with each device. Data on other standard metrics for lung function (e.g., peak expiratory flow or the ratio of FEV1/FVC) were not considered here and might be worth adding, if available. More details on quality control should be provided for the lung function data. L210-211: additional guidance should be provided for readers regarding the interpretation of 95% limits of agreement. Results Table 3: “V good” and “V poor” should be spelled out. Table 4: “Some/lot difficulting gripping” needs revision. The data on reliability provided in Table S2 are of interest. Could the authors provide information about what these reliability estimates translate to in terms of variation in units of measurement? This would likely help readers better interpret the results regarding between-device differences. L275: “… the analyses”. The large differences between digital dynamometers and manual ones are of interest. Did these discrepancies vary by experimenter? Discussion L340: please explain why the age of the sample would be a relevant consideration here. L345: “55 participants aged …” would make for easier reading. L364: given the strong non-linear associations between age and several of these measures (e.g., Mutz et al. 2021, Aging, doi: 10.18632/aging.203275 in a large UK sample), it is perhaps difficult to talk about the equivalent of a 5-year age difference, especially for measures like diastolic blood pressure. L405: although this suggestion is appropriate within studies, I am not sure about the feasibility of conducting such experiments when making comparison between studies (which are typically secondary data analyses / meta-analyses). L426: “irrepsctive” -> “irrespective”. Could the authors comment on how statistically significant differences, for example, between groups should be interpreted if such differences are smaller in magnitude than some of the differences observed here between devices for the same device across multiple measurements? ****** 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. Attachments Attachment Submitted filename: Review_PONE-D-22-31125.docx https://doi.org/10.1371/journal.pone.0289052.r001
Revision 1
28 Apr 2023 Author Response We are grateful to the reviewers for the time taken to review this paper and the helpful comments provided. Reviewer #1 Carli Lessof et al. used a randomized cross-over study to compare different devices for their measurement of blood pressure, grip strength and lung function. All the measurements and analyses were performed to a good technical standard. Measurement differences between devices are bound to exist, however, the article does not provide information for us to choose a better device. I recommend comparing these devices to standard devices such as mercury sphygmomanometer. Response: We thank the reviewer for acknowledging that our study was performed to a good technical standard. The intention of the study was not to aid selection of a “better device” nor to compare new devices with a standard machine, but rather to aid within- and between-study comparison of devices already commonly used in longitudinal studies. We therefore selected devices which had commonly been used in key UK longitudinal population studies for which there was a lack of previous comparison information. There have been multiple previous studies comparing the manual sphygmomanometers, including mercury ones, with automated devices (see references 16-20), but few comparing different automated devices. We have made edits to the introduction to make clearer the rationale for the choice of machines compared in our study (lines 81-104). Reviewer #2: The manuscript is well-written, and the research question is clearly defined. The study is scientifically sound, and I have no significant concerns. I therefore provide only minor comments and suggestions which I hope the authors will find useful in improving the presentation of their work. Response: We thank the reviewer for their positive comments and for the very helpful suggestions which we feel have improved the manuscript. Abstract It would be useful to state that multiple measurements were taken for each device. Response: This information has been added to the abstract (line 49). L58: consider providing quantitative estimates with the statement that “differences were small”, for example the range of mean differences. Response: The estimates and 95% confidence intervals have been added (lines 59 and 60). Key implications of the findings for statistical analyses could be more specific, addressing how these findings should be considered when “modelling intra-individual changes in function and when carrying out cross-study analyses.” Response: The implications have been edited to make this clearer and highlight that we might expect sensitivity analyses to be carried out (lines 66-67). Introduction A brief paragraph discussing the test-retest reliability of these devices would be useful to contextualise the findings regarding difference between devices. How do measurements taken with the same device vary in magnitude compared to differences between devices? Response: On review of the literature, there was little good quality information on test-retest reliability across the devices used in this study. We therefore decided not to include a paragraph in the introduction, but we acknowledge that this is an important point to consider. Therefore, in response to this point, and others below, we have added the within-person standard deviations to Table S2 (and discuss in lines 254-260) and further discussion of reliability in interpretation of the findings (lines 391-394, 406-407, 413-416, 430-435). L89-91: could these differences instead be accounted for in the analyses? It would be useful if the authors would be more specific about what they mean by “in some instances”. Response: We have clarified this sentence in that it relates to specific recommendations regarding the use of spirometers in UK studies (line 94). L94: although the authors cite multiple studies, they state that the “evidence is limited”. Response: We have edited the final paragraph of the introduction to make clearer our choice of machines to compare (lines 97-104). L98 (and elsewhere): I suggest avoiding unnecessary acronyms such as “BP” for blood pressure. Response: We have used blood pressure instead of BP and also replace LOA with limits of agreement and BMI with body mass index. We welcome editorial guidance on any other acronyms that should be replaced. Methods L104: consider providing the name of the guidelines (CONSORT) here. Response: “CONSORT” has been added (line 110). L109: “and the South East” of England. Response: This has been corrected (line 115). L119: “anonymised” -> “pseudo anonymised”. Response: This had been corrected (line 125). Please provide the justification/rationale for using a randomised cross-over study design. This might seem obvious, but it is useful to state this explicitly in the text. Response: We thank the reviewer for highlighting the need for clarification. The rationale for using a randomised cross-over study design has now been added. “…so as to make within-person measurement comparisons” (lines 109). As noted above, it would be useful to state earlier that multiple measurements were taken with each device. Response: This has now been stated in the “Study Design and Sample” section (lines 135-136). Data on other standard metrics for lung function (e.g., peak expiratory flow or the ratio of FEV1/FVC) were not considered here and might be worth adding, if available. Response: FEV1 and FVC are the gold standard measures for lung function and therefore are the ones that are derived from spirometers in longitudinal population studies and used in analyses. PEFR is seen as an approximation of FEV1, and is therefore no longer used where FEV1 measures are available. FEV1 and FVC were thus chosen a priori as primary outcomes measures. Given these measures were defined in our protocol, we feel that it would not be good practice to add PEFR as an outcome at this stage and, although available, our protocol was not set up to standardise PEFR measurement. We do acknowledge the interest in the FEV1/FVC particularly in detecting COPD, and we have thus added a sentence to the discussion on the likely impact of our findings on FEV1/FVC (lines 418-419). Given that this outcome is a ratio of two measurements, a comparison between devices would not be informative as differences would be a combination of the variation in the individual components. If adjustment for a change in device was to be made, it would be to the component measures (FEV1 or FVC) rather than the ratio. More details on quality control should be provided for the lung function data. Response: We have added details on the quality control (lines 201-203). In relation to this, we also clarified that participants had five attempts to produce three valid measures (lines 179-180). L210-211: additional guidance should be provided for readers regarding the interpretation of 95% limits of agreement. Response: This has been added (lines 220-221), as has a clearer description of the Bland-Altman plot which also aids interpretation (lines 217-218). Results Table 3: “V good” and “V poor” should be spelled out. Response: These have been spelled out. Table 4: “Some/lot difficulting gripping” needs revision. Response: This has been edited. The data on reliability provided in Table S2 are of interest. Could the authors provide information about what these reliability estimates translate to in terms of variation in units of measurement? This would likely help readers better interpret the results regarding between-device differences. Response: We have added the within-person standard deviation, which are in the original units, for each device and measurement to Table S2. We have added additional text describing the content of this table, including highlighting the repeatability is part of the spirometry quality control (lines 254-260). L275: “… the analyses”. Response: This has been corrected. The large differences between digital dynamometers and manual ones are of interest. Did these discrepancies vary by experimenter? Response: Given that this is a within-person comparison study, and the same experimenter (assessor) tested the same person on all machines, while the individual measurements may have varied according to experimenter (due, for example, to different levels of encouragement), we did not anticipate that they would have had a great impact on the differences. However, we did consider the potential impact of assessor variation in preliminary multilevel model analyses. These models showed that the variation by assessor, as anticipated, was small (and was statistically non-significant), and inclusion of this source of variation did not change the main findings. Therefore, we chose not include assessor in our final analyses and can conclude therefore that assessor does not explain the wide variation in differences in grip strength. We do now acknowledge that assessor is an additional source of variation which we have not accounted for in the study and have added this to the discussion (lines 448-449). Discussion L340: please explain why the age of the sample would be a relevant consideration here. Response: This has been explained. “However, the study population was younger, with an average age of 32 years, comprising a convenience sample of 40 men and women and may have better function than our older sample which could influence comparability across machines” (lines 361-362) L345: “55 participants aged …” would make for easier reading. Response: This has been changed (line 366) L364: given the strong non-linear associations between age and several of these measures (e.g., Mutz et al. 2021, Aging, doi: 10.18632/aging.203275 in a large UK sample), it is perhaps difficult to talk about the equivalent of a 5-year age difference, especially for measures like diastolic blood pressure. Response: we have added a caveat to this interpretation for diastolic blood pressure and acknowledge the limitation of this comparison (line 404-406). L405: although this suggestion is appropriate within studies, I am not sure about the feasibility of conducting such experiments when making comparison between studies (which are typically secondary data analyses / meta-analyses). Response: This point been edited for clarity. “Conducting external comparison studies, such as ours, would also help interpretation for both within-study and between-study comparisons.” (lines 429-430) L426: “irrepsctive” -> “irrespective”. Response: This has been corrected. Could the authors comment on how statistically significant differences, for example, between groups should be interpreted if such differences are smaller in magnitude than some of the differences observed here between devices for the same device across multiple measurements? Response: As indicated above we have added the within-person standard deviations in Table S2. We have also edited the discussion to add further comment on the interpretation (lines 391-394, 406-407, 413-416, 430-435). Attachments Attachment Submitted filename: Response to reviewers.docx https://doi.org/10.1371/journal.pone.0289052.r002
23 May 2023 Decision Letter - Masaki Mogi, Editor PONE-D-22-31125R1Comparison of devices used to measure blood pressure, grip strength and lung function: a randomised cross-over studyPLOS ONE Dear Dr. Wong, 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 manusript still needs a minor revision.See the suggetions from the reviewer and respond them appropriately. ============================== Please submit your revised manuscript by Jul 07 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, Masaki Mogi 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. [Note: HTML markup is below. Please do not edit.] 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 ******** 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: The study showed measurement differences between devices commonly used to assess BP, grip strength and lung function, the results may help within and between-study comparison of devices used in longitudinal studies. I only provide minor suggestions which I hope the authors will find useful in improving the presentation of their work 1. I suggest presenting the order of assessment (Table 2) in the form of a flowchart. 2. Please add the limitations of this study in the Discussion. Reviewer #2: Review of PONE-D-22-31125_R1 Thank you for the invitation to review the revised version of this manuscript. I thank the authors for addressing each of my previous comments and suggestions. I have no further concerns. ****** 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 ******** [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.0289052.r003
Revision 2
3 Jul 2023 Author Response Response to additional reviewers comments from 23/05/2023 Reviewer #1: The study showed measurement differences between devices commonly used to assess BP, grip strength and lung function, the results may help within and between-study comparison of devices used in longitudinal studies. I only provide minor suggestions which I hope the authors will find useful in improving the presentation of their work 1. I suggest presenting the order of assessment (Table 2) in the form of a flowchart. Response: Thank you for this suggestion. We have provided a flowchart. 2. Please add the limitations of this study in the Discussion. Response: We have made the limitations of this study more explicit and expanded the discussion. Response to original reviewers comments Reviewer #1 Carli Lessof et al. used a randomized cross-over study to compare different devices for their measurement of blood pressure, grip strength and lung function. All the measurements and analyses were performed to a good technical standard. Measurement differences between devices are bound to exist, however, the article does not provide information for us to choose a better device. I recommend comparing these devices to standard devices such as mercury sphygmomanometer. Response: We thank the reviewer for acknowledging that our study was performed to a good technical standard. The intention of the study was not to aid selection of a “better device” nor to compare new devices with a standard machine, but rather to aid within- and between-study comparison of devices already commonly used in longitudinal studies. We therefore selected devices which had commonly been used in key UK longitudinal population studies for which there was a lack of previous comparison information. There have been multiple previous studies comparing the manual sphygmomanometers, including mercury ones, with automated devices (see references 16-20), but few comparing different automated devices. We have made edits to the introduction to make clearer the rationale for the choice of machines compared in our study (lines 81-104). Reviewer #2: The manuscript is well-written, and the research question is clearly defined. The study is scientifically sound, and I have no significant concerns. I therefore provide only minor comments and suggestions which I hope the authors will find useful in improving the presentation of their work. Response: We thank the reviewer for their positive comments and for the very helpful suggestions which we feel have improved the manuscript. Abstract It would be useful to state that multiple measurements were taken for each device. Response: This information has been added to the abstract (line 49). L58: consider providing quantitative estimates with the statement that “differences were small”, for example the range of mean differences. Response: The estimates and 95% confidence intervals have been added (lines 59 and 60). Key implications of the findings for statistical analyses could be more specific, addressing how these findings should be considered when “modelling intra-individual changes in function and when carrying out cross-study analyses.” Response: The implications have been edited to make this clearer and highlight that we might expect sensitivity analyses to be carried out (lines 66-67). Introduction A brief paragraph discussing the test-retest reliability of these devices would be useful to contextualise the findings regarding difference between devices. How do measurements taken with the same device vary in magnitude compared to differences between devices? Response: On review of the literature, there was little good quality information on test-retest reliability across the devices used in this study. We therefore decided not to include a paragraph in the introduction, but we acknowledge that this is an important point to consider. Therefore, in response to this point, and others below, we have added the within-person standard deviations to Table S2 (and discuss in lines 254-260) and further discussion of reliability in interpretation of the findings (lines 391-394, 406-407, 413-416, 430-435). L89-91: could these differences instead be accounted for in the analyses? It would be useful if the authors would be more specific about what they mean by “in some instances”. Response: We have clarified this sentence in that it relates to specific recommendations regarding the use of spirometers in UK studies (line 94). L94: although the authors cite multiple studies, they state that the “evidence is limited”. Response: We have edited the final paragraph of the introduction to make clearer our choice of machines to compare (lines 97-104). L98 (and elsewhere): I suggest avoiding unnecessary acronyms such as “BP” for blood pressure. Response: We have used blood pressure instead of BP and also replace LOA with limits of agreement and BMI with body mass index. We welcome editorial guidance on any other acronyms that should be replaced. Methods L104: consider providing the name of the guidelines (CONSORT) here. Response: “CONSORT” has been added (line 110). L109: “and the South East” of England. Response: This has been corrected (line 115). L119: “anonymised” -> “pseudo anonymised”. Response: This had been corrected (line 125). Please provide the justification/rationale for using a randomised cross-over study design. This might seem obvious, but it is useful to state this explicitly in the text. Response: We thank the reviewer for highlighting the need for clarification. The rationale for using a randomised cross-over study design has now been added. “…so as to make within-person measurement comparisons” (lines 109). As noted above, it would be useful to state earlier that multiple measurements were taken with each device. Response: This has now been stated in the “Study Design and Sample” section (lines 135-136). Data on other standard metrics for lung function (e.g., peak expiratory flow or the ratio of FEV1/FVC) were not considered here and might be worth adding, if available. Response: FEV1 and FVC are the gold standard measures for lung function and therefore are the ones that are derived from spirometers in longitudinal population studies and used in analyses. PEFR is seen as an approximation of FEV1, and is therefore no longer used where FEV1 measures are available. FEV1 and FVC were thus chosen a priori as primary outcomes measures. Given these measures were defined in our protocol, we feel that it would not be good practice to add PEFR as an outcome at this stage and, although available, our protocol was not set up to standardise PEFR measurement. We do acknowledge the interest in the FEV1/FVC particularly in detecting COPD, and we have thus added a sentence to the discussion on the likely impact of our findings on FEV1/FVC (lines 418-419). Given that this outcome is a ratio of two measurements, a comparison between devices would not be informative as differences would be a combination of the variation in the individual components. If adjustment for a change in device was to be made, it would be to the component measures (FEV1 or FVC) rather than the ratio. More details on quality control should be provided for the lung function data. Response: We have added details on the quality control (lines 201-203). In relation to this, we also clarified that participants had five attempts to produce three valid measures (lines 179-180). L210-211: additional guidance should be provided for readers regarding the interpretation of 95% limits of agreement. Response: This has been added (lines 220-221), as has a clearer description of the Bland-Altman plot which also aids interpretation (lines 217-218). Results Table 3: “V good” and “V poor” should be spelled out. Response: These have been spelled out. Table 4: “Some/lot difficulting gripping” needs revision. Response: This has been edited. The data on reliability provided in Table S2 are of interest. Could the authors provide information about what these reliability estimates translate to in terms of variation in units of measurement? This would likely help readers better interpret the results regarding between-device differences. Response: We have added the within-person standard deviation, which are in the original units, for each device and measurement to Table S2. We have added additional text describing the content of this table, including highlighting the repeatability is part of the spirometry quality control (lines 254-260). L275: “… the analyses”. Response: This has been corrected. The large differences between digital dynamometers and manual ones are of interest. Did these discrepancies vary by experimenter? Response: Given that this is a within-person comparison study, and the same experimenter (assessor) tested the same person on all machines, while the individual measurements may have varied according to experimenter (due, for example, to different levels of encouragement), we did not anticipate that they would have had a great impact on the differences. However, we did consider the potential impact of assessor variation in preliminary multilevel model analyses. These models showed that the variation by assessor, as anticipated, was small (and was statistically non-significant), and inclusion of this source of variation did not change the main findings. Therefore, we chose not include assessor in our final analyses and can conclude therefore that assessor does not explain the wide variation in differences in grip strength. We do now acknowledge that assessor is an additional source of variation which we have not accounted for in the study and have added this to the discussion (lines 448-449). Discussion L340: please explain why the age of the sample would be a relevant consideration here. Response: This has been explained. “However, the study population was younger, with an average age of 32 years, comprising a convenience sample of 40 men and women and may have better function than our older sample which could influence comparability across machines” (lines 361-362) L345: “55 participants aged …” would make for easier reading. Response: This has been changed (line 366) L364: given the strong non-linear associations between age and several of these measures (e.g., Mutz et al. 2021, Aging, doi: 10.18632/aging.203275 in a large UK sample), it is perhaps difficult to talk about the equivalent of a 5-year age difference, especially for measures like diastolic blood pressure. Response: we have added a caveat to this interpretation for diastolic blood pressure and acknowledge the limitation of this comparison (line 404-406). L405: although this suggestion is appropriate within studies, I am not sure about the feasibility of conducting such experiments when making comparison between studies (which are typically secondary data analyses / meta-analyses). Response: This point been edited for clarity. “Conducting external comparison studies, such as ours, would also help interpretation for both within-study and between-study comparisons.” (lines 429-430) L426: “irrepsctive” -> “irrespective”. Response: This has been corrected. Could the authors comment on how statistically significant differences, for example, between groups should be interpreted if such differences are smaller in magnitude than some of the differences observed here between devices for the same device across multiple measurements? Response: As indicated above we have added the within-person standard deviations in Table S2. We have also edited the discussion to add further comment on the interpretation (lines 391-394, 406-407, 413-416, 430-435). Attachments Attachment Submitted filename: Response to reviewers2.docx https://doi.org/10.1371/journal.pone.0289052.r004
11 Jul 2023 Decision Letter - Masaki Mogi, Editor Comparison of devices used to measure blood pressure, grip strength and lung function: a randomised cross-over study PONE-D-22-31125R2 Dear Dr. Wong, 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, Masaki Mogi Academic Editor PLOS ONE Additional Editor Comments (optional): Reviewers' comments: https://doi.org/10.1371/journal.pone.0289052.r005
Formally Accepted
3 Aug 2023 Acceptance Letter - Masaki Mogi, Editor PONE-D-22-31125R2 Comparison of devices used to measure blood pressure, grip strength and lung function: a randomised cross-over study Dear Dr. Wong: 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. Masaki Mogi Academic Editor PLOS ONE https://doi.org/10.1371/journal.pone.0289052.r006

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