The information below details the section headings that you should include in your manuscript and what information should be within each section.
Please note that your manuscript must include a 'Declarations' section including all of the subheadings (please see below for more information).
This should list the title of the article. The title should include the review question, for example: What is the effectiveness of intervention A in producing change in subject B? What is the impact of factor X on subject Y?
The title should also indicate that it is a systematic review, for example:
- What is the effectiveness of intervention A in producing change in subject B? A systematic review.
- What is the impact of factor X on subject Y? A systematic review.
The full names, institutional addresses, and email addresses for all authors must be included on the title page. The corresponding author should also be indicated.
The Abstract of the manuscript should not exceed 500 words and must be structured into the following separate sections:
Background, the context and purpose of the review, including the review question;
Methods, how the review was performed including brief overview of all methodological steps and statistical tests used;
Review findings, the main findings, including results of search and assessment of evidence base;
Conclusions, brief summary and potential implications for policy/management and research.
Three to ten keywords representing the main content of the article should be given. Please avoid repeating words that are already in the title.
The Background section should be written in a way that is accessible to researchers without specialist knowledge in that area and must clearly state - and, if helpful, illustrate - the background to the review and its aims. Reports should indicate why this study was necessary and what it aimed to contribute to the field. A theory of change and/or conceptual model should be presented that links the intervention or exposure to the outcome. The role of stakeholders in the formulation of the question should be described and explained. The section should end with a brief statement of what is being reported in the article. A clear reference should be made to the protocol and any differences between what was planned and what was conducted.
Objective of the Review
This section should describe the primary question and secondary questions when applicable. The primary question is the main question of the review. The secondary questions are usually linked to possible subgroup analyses. This section may also present definitions of the primary question components (e.g. the subject, intervention and outcome measure) but see ‘study eligibility criteria’ below.
This section should describe the design and conduct of the review. Although the methods may be somewhat repetitive of the protocol they should be given in full. Direct citation of the protocol should be made here. A clear description of all review stages should typically follow the format below;
Deviations from the protocol
Here describe any differences in methods to the ones proposed in the protocol including changes to searching, eligibility criteria and screening process, critical appraisal, data extraction and synthesis. Please justify these changes.
Search for articles
Here all searches should be described in sufficient detail so as to be replicable. The following bullet points are a guide to the subsections and detail required in describing the search strategy, the sources searched and how the search was conducted, including limitations.
- Search terms and strings: How were decisions made and justified on the search terms and languages in which search was conducted? All search strings used for each of the searches conducted (including searches via search engines, publication databases and specialist websites) should be provided in a supplementary file. Search strings should be provided exactly as they were used, including combinations of terms using Boolean operators (AND, OR, NOT, etc.), wildcards (to include alternative forms of words, plurals, etc.) or any other special characters. Where searches could not be conducted using search strings, but individual search terms were used, those terms should also be listed. Trial development of search strings (if not included in the protocol) may also be included as an Additional File.
- Search limitations: State date ranges imposed on the search with justification. State all languages in which searches were conducted and any limitations this may impose on the review.
- Search sources: List all publication databases, citation indexes and other services that were searched, including details of institutional subscriptions used to access these services (or date ranges subscribed for each database searched), search options (e.g. ‘topic words’ or ‘full text’ search facility) and dates of searches.
- Search sources: List all search engines used, including a description of search options (e.g. title search) and dates of searches. Justify any strategy to limit the number of search results considered. Describe how you coped with limitations to using search strings if any.
- Search sources: Searches of organisational websites should be described, including a list of websites searches, dates of searches, any filtering or limitations applied.
- Supplementary searches: Supplementary searches should also be described so as to be replicable. These include Bibliographical searches, ‘snowballing’ or obtaining literature from experts or stakeholders (via open calls and similar).
- Estimating the comprehensiveness of the search: If not reported at the protocol stage, please state how you tested the comprehensiveness of your search. For example, did you compile a benchmark list of relevant studies to test the sensitivity of your searches?
- Search results: You may also describe how you assembled a library of search results i.e. how you combined and deduplicated search results and which reference (or review) management software you used to do this.
Article screening and study eligibility criteria
Describe the article screening process and decisions regarding eligibility, at title, abstract, full-text level. Describe how the consistency of eligibility decisions was measured and reported, and how disagreements between reviewers were resolved so as to inform subsequent decisions.
Confirm the exclusion of the review team members (who have also authored articles considered within the review) from decisions regarding inclusion or study validity assessment of their own work.
Eligibility criteria should be precisely defined (e.g. reliance on broad and potentially ambiguous terms should be avoided) and expressly related to each key element of the question. Here describe criteria and definitions followed to include eligible articles so that this stage is transparent and replicable. You may add examples of both eligible and ineligible articles to clarify the criteria. Organise this section according to following subsections (or equivalent for other question types):
- Eligible population(s) or subject(s)
- Eligible intervention(s) or exposure(s)
- Eligible comparator(s) (if appropriate)
- Eligible outcomes
- Eligible types of study design
- Any additional criteria
Study validity assessment
Describe here the methods you used to critically appraise and assess the validity of included studies. An explanation should be given of how both internal validity (risk of bias) and external validity (generalisability of a study’s results to your Systematic Review question). Regarding internal validity, an effort should be made to identify risk of bias relevant to individual included studies. Each type of bias or threat to internal and external validity should be assessed individually for all included studies and reported on a critical appraisal sheet. Provide any checklists used. Describe how the consistency of critical appraisal decisions was tested.
Describe how the results of this assessment were used in synthesis (e.g. subgroup or sensitivity analysis).
Data coding and extraction strategy
State what categories of data and meta-data were intended to be extracted. Describe here the methods by which data and meta-data from each study were extracted so that the process can be replicated. Specifically, state how outcome data and associated meta-data from included studies were recorded. Provide any spreadsheets (codebooks and data extraction forms) used. State how you tested the consistency of data extraction process among reviewers. Describe any process for obtaining and confirming missing or unclear information or data from authors of studies included in this process.
Potential effect modifiers/reasons for heterogeneity
Confirm or update the list of the effect modifiers and reasons for heterogeneity considered in the review. Provide details of how the list was compiled (including consultation of external experts). Justify the choice of modifiers (e.g. in the context of your theory of change and external validity of findings).
Data synthesis and presentation
Describe here the methods you used to synthesise the extracted data and any subsequent manipulation of the data set (e.g. sub-group analyses). Synthesis methodology should be justified and fully explained. Narrative synthesis methodology should be provided, and a description of all included studies confirmed. If all studies were not selected for further data synthesis (e.g. meta-analysis) explain criteria for selection (e.g. incomplete or missing information, heterogenous outcomes).
If data are appropriate for quantitative synthesis (e.g. meta-analysis), sufficient details should be provided for the synthesis to be replicable. Methods for calculating effect sizes or any other statistical methods for combining data from individual studies, and exploration of heterogeneity and publication bias should be described.
Results of each stage of the review (e.g. search statistics, eligibility, study validity assessment, data extraction, reasons for variability in the results found and potential confounding factors, summary statistics) should be clearly reported. A narrative synthesis of all eligible studies should always be provided. Results of any statistical syntheses should be fully reported with appropriate figures, tables and statistical values. Subsections should follow the format:
Review descriptive statistics
Report here the number of articles and the studies therein found in the search. A flow diagram reporting all stages of the inclusion/exclusion process, from search results to full text eligibility, should be presented. Results of consistency checking at all stages must be provided.
Descriptive statistics should be provided on any relevant information on the distribution of the articles found (e.g. geographical, temporal, institutional) in order to assess potential gaps or bias in the evidence. Some systematic mapping of the evidence could be provided here if this was conducted as an intermediate step. For full transparency, additional files are expected here including:
Tables of search results showing where eligible articles were found (i.e. through which database etc) A full reference list of all eligible articles A list of studies excluded at full text together with reasons for exclusion (reasons for exclusion should match your eligibility criteria).
Narrative synthesis including study validity assessment
A narrative synthesis will normally be provided as text and be supported by tables/figures, either in the main body of the paper or as an additional file. Data extracted from each study, including metadata and individual study findings, along with other key information such as study location and reporting of effect modifiers should be presented as a table or additional file. For each and all studies provide a summary of validity assessments as a table and clarify which of the eligible studies were included in/excluded from quantitative (or other types of) synthesis and provide reasons for these decisions.
Report here results of any synthesis of extracted data. If meta-analyses have been conducted present full details (some of the results can be made available as additional files), including effect sizes, Forest plots and related statistics (e.g. tests for heterogeneity) and, if possible, results of tests for potential biases (e.g. funnel plots). Data should have been utilised to their full potential to answer the question, including sensitivity (e.g. based on study validity assessment) and subgroup analysis. It should be clear how the results of study validity assessment have been used in the synthesis.
If a meta-analysis has been conducted please present an evaluation of the level of variation in effect of the intervention/exposure and possible reasons for these variations by evaluating the impact of study validity and other effect modifiers (such as experimental design, etc.).
A detailed and reflective discussion of the limitations of the review is expected here, including limitations due to the search strategy (limitations of the review methods), as well as limitations due to underlying bias within the studies found such as baseline bias and confounding variables (limitations of the evidence base). Gaps in the information provided by the primary studies should also be highlighted. Please do not provide a discussion section that includes speculation or expert opinion concerning the review findings.
This section should be divided into:
Implications for Policy/Management
This section should summarise the state of the evidence base and the extent to which this informs decision making in relation to the review question and any measure of the uncertainty surrounding the outcome. The intention is to inform based on the findings, and any form of advocacy or speculation should be avoided. Keep it short and understandable to those not expert in the subject.
Implications for Research
This section summarises the shortcomings of the current evidence base in terms of knowledge gaps and the need for further primary research. In this section advocacy for research is permissible provided it is clearly justified by the review findings. This should take the form of recommendations for future study questions and designs that would improve the evidence base.