PONE-D-23-42547Guided self-help treatment for children and young people with threshold and subthreshold eating disorders: A pilot study protocolPLOS ONE

Dear Dr. Davey,

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Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

1. Does the manuscript provide a valid rationale for the proposed study, with clearly identified and justified research questions?

The research question outlined is expected to address a valid academic problem or topic and contribute to the base of knowledge in the field.

Reviewer #1: Yes

Reviewer #2: Yes

Reviewer #3: Yes

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2. Is the protocol technically sound and planned in a manner that will lead to a meaningful outcome and allow testing the stated hypotheses?

The manuscript should describe the methods in sufficient detail to prevent undisclosed flexibility in the experimental procedure or analysis pipeline, including sufficient outcome-neutral conditions (e.g. necessary controls, absence of floor or ceiling effects) to test the proposed hypotheses and a statistical power analysis where applicable. As there may be aspects of the methodology and analysis which can only be refined once the work is undertaken, authors should outline potential assumptions and explicitly describe what aspects of the proposed analyses, if any, are exploratory.

Reviewer #1: Partly

Reviewer #2: No

Reviewer #3: Partly

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3. Is the methodology feasible and described in sufficient detail to allow the work to be replicable?

Descriptions of methods and materials in the protocol should be reported in sufficient detail for another researcher to reproduce all experiments and analyses. The protocol should describe the appropriate controls, sample size calculations, and replication needed to ensure that the data are robust and reproducible.

Reviewer #1: Yes

Reviewer #2: Yes

Reviewer #3: Yes

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4. Have the authors described where all data underlying the findings will be made available when the study is complete?

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Reviewer #1: Yes

Reviewer #2: Yes

Reviewer #3: Yes

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5. Is the manuscript presented in an intelligible fashion and written in standard English?

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Reviewer #1: Yes

Reviewer #2: Yes

Reviewer #3: Yes

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6. Review Comments to the Author

Please use the space provided to explain your answers to the questions above and, if applicable, provide comments about issues authors must address before this protocol can be accepted for publication. You may also include additional comments for the author, including concerns about research or publication ethics.

You may also provide optional suggestions and comments to authors that they might find helpful in planning their study.

(Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #1: This is a comprehensive and detailed protocol for a pilot study and process evaluation to assess the initial effectiveness, feasibility and acceptability of a newly developed CBT-based guided self-help intervention for a small group of children and young people (CYP) with a range of eating disorder diagnoses and severity. Recent consensus in programme-led interventions for young people with eating disorders, highlights the need for work in this area.

The manuscript meets the PLOS publication criteria including originality, clearly outlined methodology, presentation, writing style and clearly reported ethical approval, trial registry and reporting checklist.

Rationale and research questions clearly stated?

Excellent and succinct rationale for conducting the pilot study with clearly outlined aims. This could be strengthened further by linking to the recently published consensus statement for programme-led interventions to highlight the need, not only to improve provision of such interventions but also to optimise access and adherence

I the protocol technically sound to enable to test stated hypotheses?

The protocol is technically sound and presented in line with the SPIRIT checklist for clinical trials protocols.

However, I have slight concerns about the sample size of 10 CYP with a range of eating disorder presentations and the known drop-out rate in existing guided self-help interventions (circa 40%). This limits the conclusions the authors are able to make. Findings will be simply indicative as the authors acknowledge.

Is the methodology described in sufficient detail for replication?

The authors present the methods with an excellent level of detail and they are presented in line with SPIRIT checklist for clinical trial protocols, including important information such as strategies to improve adherence/ fidelity, criteria for discontinuation, managing risk.

Eligibility criteria: please state which screening tool you will use to determine whether an individual meets diagnostic criteria for an eating disorder

It would be useful to present details of the intervention using the TIDIER checklist

Outcome: Make clear which your primary outcome will be - EDEQ? And also whether you are interested in global score, cut-off or a particular behavioural feature? It would be useful to state this for each outcome measure in the text.

Have authors stated where data will be made available when complete?

This is a Protocol Paper therefore no data will be generated. The authors provide plans for dissemination in peer reviewed journals and academic conferences on completion of the study.

Is the manuscript written in an intelligible fashion?

The authors write in a clear and concise manner throughout

Additional comments:

In the Methods section of the abstract, please make clear the mode of guidance, as this is important (remotely)

In the abstract consider describing the study design as ‘open pilot trial and process evaluation’ so congruent with Study Design section in main text.

Study Design: Again, outline mode of guidance (remotely)

26a – simplify heading to ‘Informed consent and assent’ rather than a question

11a Intervention – it would be useful to provide details of the process of intervention development. Was it through principles of co-production? If so, how did you go about it?

Reviewer #2: You are planning a small sample size that will be recruiting from a variety of eating disorder types. Will your sample size be able to offer a sufficient evidence for your intervention's efficacy across these different diagnoses?

NICE guidelines recommend a range of treatment options depending on the classification of eating disorder. Do you expect your intervention to be suitable for all eating disorder types?

Reviewer #3: Important note: This review pertains only to ‘statistical aspects’ of the study and so ‘clinical aspects’ [like medical importance, relevance of the study, ‘clinical significance and implication(s)’ of the whole study, etc.] are to be evaluated [should be assessed] separately/independently. Further please note that any ‘statistical review’ is generally done under the assumption that (such) study specific methodological [as well as execution] issues are perfectly taken care of by the investigator(s). This review is not an exception to that and so does not cover clinical aspects {however, seldom comments are made only if those issues are intimately / scientifically related & intermingle with ‘statistical aspects’ of the study}. Agreed that ‘statistical methods’ are used as just tools here, however, they are vital part of methodology [and so should be given due importance]. I look at the manuscript in/with statistical view point, other reviewer(s) look(s) at it with different angle so that in totality the review is very comprehensive. However, there should be efforts from authors side to improve (may be by taking clues from reviewer’s comments). Therefore, please do not limit the revision only (with respect) to comments made here.

COMMENTS: There are very few issues/observations about which I have different opinion [mainly they are suggestions for further larger study (If the intervention is shown to be effective in this pilot study, a fully powered randomised controlled trial will be warranted with the ultimate goal of increasing access to psychological treatment for children and young people threshold and subthreshold eating disorders)]. Such observations/concerns are given below:

This study being ‘pilot’ (feasibility study) in nature, sample size is not a big issue. However, as mentioned in line 264 [This pilot study aims to recruit up to 10 eligible children and young people] the sample size intended to be used for this study is questionably small {as unlikely to get fair idea of attrition rates at each stage as said in line 338 and also unlikely to yield/produce an estimate of effect size which can be used to design a fully powered randomised controlled trial” as said in lines 386-88}. Further, though many things are ignored (loosely looked at / evaluated)] in case of ‘pilot studies’, methodological issues need to be very rigorously followed {in contrast with / despite often quote: “Pilot (Proof of Concept) studies typically involve a small number of subjects, as well as more latitude [i.e., leeway, freedom, liberty] in statistical requirements”}.

I request authors to read following note pasted from one famous standard textbook on ‘Medical Research Methodology’ [though I am sure that these learned authors already know these things] as it is very essential to keep the limitations in mind while interpreting results {note that I am not asking you to change the design of this pilot study}.

For a pilot study it is alright to have ‘single-arm design’, or it is alright when that is the only possibility’, however, it is very essential to keep the limitations in mind while interpreting results. Further, note that a classical/ideal clinical trial/study needs/requires a concurrently {but similarly} handled/treated appropriately selected/chosen control/comparison parallel group/arm.

Mind you further that any “Inferential statistics (i.e., hypothesis testing + estimation of CI) is built on the population model [which means the underlying assumption is that there is/are population(s) and we are dealing with random sample(s) drawn from that/those population(s)]. Although in clinical trial (involving at least two groups) we do not really deal with random samples (generally a non-probabilistic convenience sampling), ‘allocation’ to treatment groups is ‘randomly’ done which enable us to evoke the population model and we can use inferential statistics safely. But when there is only one group (so that there is no question of random allocation), with ‘non-random’ selection, it may be questionable to use inferential statistics even if you have two measurement sets as ‘pre-post’ or many repeated measurements or use ‘internal grouping for comparison.”

While planning larger study you may consider using ‘wait listed’ control group. Though the measures/tools used (in this pilot phase and few may be used in larger study) are appropriate, most of them are likely to yield data that are in ‘ordinal’ level of measurement [and not in ratio level of measurement for sure {as the score two times higher does not indicate presence of that parameter/phenomenon as double (for example, a Visual Analogue Scales VAS score or say ‘depression’ score)}]. Then application of suitable non-parametric (or distribution free) test(s) is/are indicated/advisable [even if distribution may be ‘Gaussian’ (also called ‘normal’)]. Agreed that there is/are no non-parametric test(s)/technique(s) available to be used as alternative in all situation(s), but should be used whenever/wherever they are available.

Therefore, in short use suitable non-parametric test(s)/technique(s) while dealing with data that are in ‘ordinal’ level of measurement even if [despite that] the distribution may be ‘Gaussian’. Testing ‘normality’ in sample [by using any normality test(s)} is not required/desired while dealing with data that are in ‘ordinal’ level of measurement [as most of the normality tests are not valid for ‘ordinal’ data].

On the backdrop of what is stated in ‘Abstract- Methods’ that “A mixed-method open pilot trial design will be used” please note that any regression techniques are not basically/originally developed for any sort of [between or within group(s)] comparison(s). Moreover, a brief note on intervention designed may be expected/desirable/appreciated, by most of the readers, I guess. Except these few points, this manuscript is ‘excellent’ and therefore only ‘Minor revision’ is recommended.

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Reviewer #1: Yes: Dr Gemma D Traviss-Turner

Reviewer #2: Yes: Eleanor May Bowes

Reviewer #3: No

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Guided self-help treatment for children and young people with threshold and subthreshold eating disorders: A pilot study protocol

PONE-D-23-42547R1

Dear Dr. Davey,

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Kind regards,

Simone Varrasi

Academic Editor

PLOS ONE

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