Prevalence of mental, behavioural or neurodevelopmental disorders according to the International Classification of Diseases 11: a scoping review protocol

The purpose of this review is represented by its rationales

• Rationale 1: the rationale of this review is to outline how prevalence rates of MBND of ICD-11 have been assessed so far and thereby summarise the approaches of currently available primary studies.

  • Associated review questions are:

    • What are the sample characteristics of primary studies?

    • Where were the primary studies based?

    • What was the timeframe for data collection within primary studies?

      • Study period.

      • Year of data collection.

    • What are the study designs of primary studies?

    • What were research aims of the primary studies?

    • Which MBND are most frequently assessed?

    • How were diagnoses assessed?

    • What prevalence was estimated for the diagnoses?

  • Additionally, research gaps will be identified:

• Rationale 2: identify mental, behavioural or neurodevelopmental disorders most suitable for subsequent systematic reviews and meta-analyses: here we are interested in:

  • Disorders, where multiple (≥2) primary studies exist which assess the prevalence of the disorders listed below (table 1) according to ICD-11 criteria and ICD-10 criteria within one cohort.

  • Newly introduced disorders, where multiple (≥2) primary studies exist which assess the prevalence of the disorders listed below (table 1) according to ICD-11 criteria.

As is reflected within these rationales, the main outcome of our project is a summary of the study characteristics of a body of work. A scoping review lends itself to the most appropriate method of evidence synthesis.

A preliminary search of MEDLINE, Embase and PsycINFO for existing scoping and systematic reviews on the topic was performed on 6 October 2023. We did not identify reviews pertaining to a similar topic.

Eligibility criteria

We will include

1. Cross-sectional and longitudinal studies

2. assessing the prevalence of MBND listed (table 1)

3. as per ICD-11 criteria

In sight of the feasibility of our project, provision of insufficient data on full-text level of primary studies constitutes an exclusion criterion: we will exclude primary studies which fail to provide

1. Case numbers and sample size

2. Study period and period of data collection

3. Details of diagnostic procedures

Information sources

We will conduct a search for the peer-reviewed literature from 2011 to present in the following databases: MEDLINE, Embase, PsycINFO and Web of Science. No language restriction will be applied. Sources identified in other languages which require translation for the full-text screening will be translated by state-certified translators.

Search strategy

Our search strategy for the peer-reviewed databases will consist of a search string of the general pattern:

1. String element for retrieving articles on each of the specific diagnoses as listed in table 1

2. String element for retrieving diagnoses according to ICD-11 criteria

3. Search filter identifying cross-sectional and longitudinal studies

The MBND listed in table 1 will be searched for.

The reference list of all included studies will be searched for additional sources. Sources of grey literature will also be identified and searched.

The search strategy was developed in consultation with an information specialist. The search string will be modified for the grey literature sources. We will repeat the search before the final analysis. The exact search strategy for MEDLINE via Ovid can be found in the online supplemental material. The planned start and end dates for this study are May 2024 and May 2026, respectively.

Data management and study selection process

After performing searches across the databases, the title and abstract of each article will be exported to EndNote. Any duplicates will be removed at this stage. The titles and abstracts of all articles will be reviewed by two reviewers (KN and SG) according to the inclusion/exclusion criteria. Disagreements at this screening stage will be resolved by consensus of a third reviewer (SF) and studies will be retrieved for full-text review, if not excluded at this stage. Similarly, the full-text review will be conducted by two reviewers and disagreements will be resolved by consulting a third reviewer.

Data extraction

Following the review of titles and abstracts, an Excel spreadsheet will be created for the full-text review where the reviewers will have to document (a) whether the article is to be included or excluded, (b) record the reason for exclusion for excluded sources and (c) extract key information from each included paper. Data will be extracted by two reviewers, and discrepancies will be solved by a third reviewer.

The data extraction form will be piloted on a sample of the included studies and possibly modified.

Inclusion of a primary source provided; we intend to contact authors for further information when necessary.

Concerning the data extraction—in alignment with the aims of this project—our current data extraction form contains the following items:

1. Bibliographic information

   1. Last name of the first author

   2. Year of publication

   3. Peer-review status (peer reviewed: eg, yes, no as in preprint)

   4. Journal/source

2. Study location

3. Study period/year of data collection

4. Study design

5. Scope of the investigation/research aims

   1. Investigating the prevalence

   2. Investigating predictors

   3. Investigating consequences

   4. Investigating psychosocial correlates

6. Study sample

   1. Study sample (as in sampling process)

   2. Sample size

   3. Age range of the study population

   4. Sex/gender ratio

7. Psychiatric disorders assessed

8. Diagnostic tool

   1. Measurement tools used

   2. Method(s) of data collection

9. Prevalence of psychiatric disorders

10. Analysis performed

As these data points provide the basis for an appropriate description of the methodology of this body of work, we cannot distinguish between main and additional outcomes.

Due to the aim of our work (ie, to give an overview of prevalence data available and methodological approaches used to obtain these estimates), we will use the JBI prevalence critical appraisal tool (possibly with minor modifications) to assess the methodological limitations or risk of bias of the evidence of primary studies included.

Data synthesis

For all studies meeting the inclusion criteria of the scoping review, we will use a descriptive synthesis approach. Our summary will focus on the extracted data. The results will be presented as charts, maps or tables. We will choose those visualisation and summary approaches that best fit the extracted content.

Patient and public involvement

This project aims to analyse an existing body of research studies, and we include an expert of experience (peer-to-peer trainer) and a representative of relatives in our research group. The expert of experience (AJ) was involved in the development of this protocol and will be consulted during the process of data synthesis and the discussion of our results. The representatives of relatives will be consulted during the process of data synthesis and the discussion of our results.

Dissemination and ethics

Regarding the dissemination of our work, the scoping review will be provided to scientific journals for consideration for publication, and its results may be presented as conference posters and presentations. No ethics approval is required as the analysed data originates from publicly available material.