-->PONE-D-26-10437-->-->Assessing the appropriateness of helicopter emergency medical services for non-traumatic emergencies in a medically underserved rural area, Japan-->-->PLOS One

Dear Dr. Sada,

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.

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

Thank you for submitting your manuscript examining overtriage and undertriage of helicopter emergency medical services (HEMS) for nontraumatic emergencies. The reviewers found the topic to be clinically important and appreciated the inclusion of both HEMS and GEMS missions in the analysis. While one reviewer considered the manuscript acceptable in its current form, another reviewer raised several important concerns regarding clarity of the EMS system description, terminology, and particularly the methodology used to define and compare transport times and relative necessity. After consideration of the reviews, I believe the manuscript would benefit from revision to improve methodological transparency and interpretation of the findings. Please address the reviewer comments carefully and provide detailed responses to each point raised.

Comments from reviewer 1:

Thank you for the opportunity to review this important work. Overall, this is a well-designed study with rigorous methods and a great first step. Under-triage remains an issue. I don't necessarily see over-triage as a problem, but physiological indicators could go a long way to address both. This is named as a limitation.

Comments from reviewer 2:

This manuscript presents an interesting study examining overtriage and undertriage of HEMS for non-traumatic missions in a Japanese region.

I would like to commend the study for addressing this important topic, as this study differs from other studies by analysing both GEMS and HEMS missions to investigate the subject.

I have reviewed the manuscript carefully and to the best of my ability. If I have misunderstood any aspects, I apologize; however, if such misunderstandings arise, this may also point to areas where the manuscript could be clarified for readers.

Abstract

The abstract summarises the study satisfactorily.

Minor remarks:

Line 46: Methods. The line reads: ‘HEMS necessity was classified as “absolute” (treatment

unavailable at the locally) or…’ What is meant by locally? Is it local hospital. Please elaborate.

Introduction

The introduction is satisfactory and adequately written, establishing the context and rationale for the study. It provides a clear framework for the research questions and objectives.

Minor remarks: Line 78: ‘ …and others nothing delays in treatment for non-trauma cases transported by HEMS…’ What is meant by ‘nothing’? Should this be ‘noting’?

Methods:

Settings needs to describe in clearer terms, which level the hospitals in the region are. ‘Main local core hospital’ is not a term familiar to me. Please be more specific on which competencies are available. Are all hospitals stroke-centers with acute thrombolytic capabilities? Are cat labs available? Or have these functions been centralized.

Next, please describe which ambulance levels are available. It is written, that a physician is in the HEMS. Is there physician staffed vehicles as well? Or are ambulances always EMT/paramedic?

Regarding variables, please describe in further detail which variables are available in the dispatch data on GEMS transport.

The definition of transport-time as time from call to arrival to hospital is somewhat controversial. Usually, prehospital time is divided into response-time (call to arrival), on-scene-time (from arrival to departure) and Transport-time (time from departure to arrival to hospital). Consider using the more traditional transport-time or argue why the entire prehospital time is used.

In the definition of Relative necessity, part of the definition is ‘The patient was considered clinically unstable upon arrival’. Which arrival are we discussing here? Is it EMS arrival to scene, or patient arrival to hospital? If arrival to hospital, this definition is flawed by the prehospital treatment, depending on level of care delivered by EMS-personnel. Please elaborate on this.

It is not absolutely clear how groups are compared. It is described, how ‘To evaluate relative necessity, we compared observed transport times to estimated GEMS only travel times using historical trauma data from each region. Estimations were stratified by departure area and receiving facility.’. How is transports with GEMS only simulated? Would this be by the theoretically calculated HEMS time? And would this be by true transport-time, or total prehospital time for HEMS? If the latter, this would skew the estimates, as at least in my EMS, the GEMS prepare the patients, and the HEMS would transport the patient to the specialised facilities. In general, the historic transport times are opaque. Is this an average for all transports from the area, or is it more specific?

Results:

The results section starts with 23,327 participants, but population flowcharts starts with 3,201 participants

Sometimes only percentages are given, and sometimes both absolute numbers and percentages are given. Please always state absolute numbers as well as percentages.

In line 225 it is stated ‘However, only 253 of these patients fulfilled the full criteria for relative necessity, which required both an eligible diagnosis and a shorter estimated transport time via HEMS compared to GEMS from their respective locations.’. Is this transport time to the selected hospital the patient were historically transported to? Please make sure the methods reflects how this is measured.

The more I read on transport times, the more I am worried about the calculation. Do your EMS ever fly rendezvous missions, where the GEMS starts transports and meet the HEMS somewhere and the patient are loaded onto the HEMS for final leg of the transport? Looking at supplementary 3, these times are bizarre. How do you calculate these mission times? It really needs a breakdown of the individual time segments of prehospital times

Discussion

Discussion is adequate.

Conclusion is supported by the presented data. However, as indicated, I am not entirely convinced the data presented are brought to the best use. It appears to dismiss the cooperation of HEMS and GEMS, where HEMS fly time to mission is being used by GEMS to prep the patient for transport.

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

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We look forward to receiving your revised manuscript.

Kind regards,

Pawan Acharya, PhD, MSPH

Academic Editor

PLOS One

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Additional Editor Comments (if provided):

Thank you for submitting your manuscript examining overtriage and undertriage of helicopter emergency medical services (HEMS) for nontraumatic emergencies. The reviewers found the topic to be clinically important and appreciated the inclusion of both HEMS and GEMS missions in the analysis. While one reviewer considered the manuscript acceptable in its current form, another reviewer raised several important concerns regarding clarity of the EMS system description, terminology, and particularly the methodology used to define and compare transport times and relative necessity. After consideration of the reviews, I believe the manuscript would benefit from revision to improve methodological transparency and interpretation of the findings. Please address the reviewer comments carefully and provide detailed responses to each point raised.

[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: Partly

**********

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

Reviewer #1: Yes

Reviewer #2: Yes

**********

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Reviewer #1: Yes

Reviewer #2: No

**********

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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: Thank you for the opportunity to review this important work. Overall, this is a well-designed study with rigorous methods and a great first step. Under-triage remains an issue. I don't necessarily see over-triage as a problem, but physiological indicators could go a long way to address both. This is named as a limitation.

Reviewer #2: Review Hems Japan

This manuscript presents an interesting study examining overtriage and undertriage of HEMS for non-traumatic missions in a Japanese region.

I would like to commend the study for addressing this important topic, as this study differs from other studies by analysing both GEMS and HEMS missions to investigate the subject.

I have reviewed the manuscript carefully and to the best of my ability. If I have misunderstood any aspects, I apologize; however, if such misunderstandings arise, this may also point to areas where the manuscript could be clarified for readers.

Abstract

The abstract summarises the study satisfactorily.

Minor remarks:

Line 46: Methods. The line reads: ‘HEMS necessity was classified as “absolute” (treatment

unavailable at the locally) or…’ What is meant by locally? Is it local hospital. Please elaborate.

Introduction

The introduction is satisfactory and adequately written, establishing the context and rationale for the study. It provides a clear framework for the research questions and objectives.

Minor remarks: Line 78: ‘ …and others nothing delays in treatment for non-trauma cases transported by HEMS…’ What is meant by ‘nothing’? Should this be ‘noting’?

Methods:

Settings needs to describe in clearer terms, which level the hospitals in the region are. ‘Main local core hospital’ is not a term familiar to me. Please be more specific on which competencies are available. Are all hospitals stroke-centres with acute thrombolytic capabilities? Are cat labs available? Or have these functions been centralised.

Next, please describe which ambulance levels are available. It is written, that a physician is in the HEMS. Is there physician staffed vehicles as well? Or are ambulances always EMT/paramedic?

Regarding variables, please describe in further detail which variables are available in the dispatch data on GEMS transport.

The definition of transport-time as time from call to arrival to hospital is somewhat controversial. Usually, prehospital time is divided into response-time (call to arrival), on-scene-time (from arrival to departure) and Transport-time (time from departure to arrival to hospital). Consider using the more traditional transport-time or argue why the entire prehospital time is used.

In the definition of Relative necessity, part of the definition is ‘The patient was considered clinically unstable upon arrival’. Which arrival are we discussing here? Is it EMS arrival to scene, or patient arrival to hospital? If arrival to hospital, this definition is flawed by the prehospital treatment, depending on level of care delivered by EMS-personnel. Please elaborate on this.

It is not absolutely clear how groups are compared. It is described, how ‘To evaluate relative necessity, we compared observed transport times to estimated GEMS only travel times using historical trauma data from each region. Estimations were stratified by departure area and receiving facility.’. How is transports with GEMS only simulated? Would this be by the theoretically calculated HEMS time? And would this be by true transport-time, or total prehospital time for HEMS? If the latter, this would skew the estimates, as at least in my EMS, the GEMS prepare the patients, and the HEMS would transport the patient to the specialised facilities. In general, the historic transport times are opaque. Is this an average for all transports from the area, or is it more specific?

Results:

The results section starts with 23,327 participants, but population flowcharts starts with 3,201 participants

Sometimes only percentages are given, and sometimes both absolute numbers and percentages are given. Please always state absolute numbers as well as percentages.

In line 225 it is stated ‘However, only 253 of these patients fulfilled the full criteria for relative necessity, which required both an eligible diagnosis and a shorter estimated transport time via HEMS compared to GEMS from their respective locations.’. Is this transport time to the selected hospital the patient were historically transported to? Please make sure the methods reflects how this is measured.

The more I read on transporttimes, the more I am worried about the calculation. Do your EMS ever fly rendez vous missions, where the GEMS starts transports and meet the HEMS somewhere and the patient are loaded onto the HEMS for final leg of the transport? Looking at supplementary 3, these times are bizarre. How do you calculate these missiontimes? It really needs a breakdown of the individual timesegments of prehospital times

Discussion

Discussion is adequate.

Conclusion is supported by the presented data. However, as indicated, I am not entirely convinced the data presented are brought to the best use. It appears to dismiss the cooperation of HEMS and GEMS, where HEMS fly time to mission is being used by GEMS to prep the patient for transport.

**********

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Reviewer #1: No

Reviewer #2: No

**********

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Assessing the appropriateness of helicopter emergency medical services for non-traumatic emergencies in a medically underserved rural area, Japan

PONE-D-26-10437R1

Dear Dr. Sada,

We’re pleased to inform you that your manuscript has been judged scientifically suitable for publication and will be formally accepted for publication once it meets all outstanding technical requirements.

Within one week, you’ll receive an e-mail detailing the required amendments. When these have been addressed, you’ll receive a formal acceptance letter and your manuscript will be scheduled for publication.

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Kind regards,

Pawan Acharya, PhD, MSPH

Academic Editor

PLOS One

Additional Editor Comments (optional):

Thank you for your thorough and thoughtful revision and for addressing the reviewers' comments in detail. The revisions have substantially improved the clarity of the manuscript, particularly regarding terminology, regional setting, and the rationale underlying the assessment of HEMS necessity.

Although some methodological limitations remain, particularly regarding the estimation of relative necessity based on historical prehospital times and the inability to account for all operational aspects of GEMS–HEMS interactions, these limitations are now appropriately acknowledged and discussed.

I believe the manuscript provides useful information that will be of interest to readers.

I am pleased to inform you that the manuscript is accepted for publication.

Reviewers' comments: