Requirements for a Systematic Review

Begin with a focused question that will guide the methods of the review. The framework used to structure the question should be appropriate for the type of review.

For intervention questions, PICO (Population, Intervention, Comparison, Outcome) is commonly used. Other question frameworks may be more appropriate for questions involving diagnosis, prognosis, etiology, qualitative evidence, or other types of evidence.

The research question should inform the review's eligibility criteria, including which populations, interventions or exposures, comparators, outcomes, study designs, settings, and other characteristics will be included.

Systematic reviews are team projects. The team should include the expertise necessary to address both the subject matter and the methods of the review.

Depending on the review, team expertise may include:

• subject or clinical expertise;
• systematic review methodology;
• literature searching and information retrieval;
• study design and critical appraisal;
• statistics or other methods of evidence synthesis; and
• project and data management.

Critical review processes such as study selection and data collection should include appropriate procedures for independent assessment and resolution of disagreements. Team composition and procedures should be planned before screening begins.

Systematic reviews require a substantial commitment of time. The amount of time needed varies considerably depending on the scope of the question, size of the literature, number and availability of team members, complexity of the included studies, and methods used for synthesis.

Before beginning, consider the time required for protocol development, searching, deduplication, screening, full-text retrieval, data extraction, risk-of-bias assessment, synthesis, manuscript preparation, and updating the search before publication.

Teams should also consider access to databases, full-text articles, citation-management software, review-management tools, statistical expertise, and other resources that may be required.

Develop the review protocol before conducting the review. Prespecifying the methods increases transparency and helps reduce the risk that decisions will be influenced by the findings encountered during the review.

A protocol typically describes:

• the rationale and objectives of the review;
• the research question;
• eligibility criteria;
• planned information sources and search methods;
• study-selection procedures;
• data-management and data-extraction procedures;
• methods for assessing risk of bias;
• outcomes and other data to be collected; and
• planned methods for synthesis and analysis.

PRISMA-P: Guidance for Systematic Review Protocols

PRISMA-P provides a checklist of recommended items to address when developing and reporting a systematic review protocol.

Registering a systematic review prospectively promotes transparency, helps reduce unintended duplication of reviews, and creates a public record of the planned methods.

PROSPERO is an international prospective register for eligible systematic reviews. Registration is free.

PROSPERO has specific eligibility requirements, and not every type of evidence synthesis can be registered. Review the current PROSPERO guidance before beginning an application. For example, scoping reviews and general literature reviews are not currently eligible for PROSPERO registration.

Registration should be completed prospectively, as early as appropriate in the review process. If PROSPERO is not appropriate for the review, other options for making a protocol publicly available may be considered.

The search should be designed to identify the evidence needed to answer the review question while minimizing bias. This generally requires searching multiple appropriate databases and may also require trial registries, citation searching, grey literature, or other sources depending on the question.

Search strategies should be developed carefully and documented in enough detail to allow them to be reproduced. Record the databases and platforms searched, complete search strategies, limits or filters used, and the date each search was run.

Involving a librarian or information specialist early in the project can help identify appropriate information sources and develop, translate, document, and update the search strategies.

Systematic reviews can generate hundreds or thousands of records. Before searching begins, decide how citations will be imported, deduplicated, screened, and tracked throughout the review.

Citation-management software such as EndNote can help manage references and remove duplicate records. Systematic-review management platforms such as Covidence can support screening, full-text review, data extraction, and other stages of the review workflow.

Learn more about Covidence at MUSM »

Before beginning the review, determine how the methodological quality or risk of bias of included studies will be assessed and which appraisal tool is appropriate for the study designs being included.

The protocol should also specify how findings will be synthesized. Depending on the review question and available evidence, this may involve meta-analysis, other quantitative synthesis methods, narrative or structured synthesis, or another appropriate approach.

See Risk of Bias »

Consider reporting requirements at the beginning of the project rather than waiting until the manuscript is written. Keeping complete records throughout the review makes accurate reporting much easier.

PRISMA 2020 provides the primary reporting guidance for systematic reviews. Appropriate PRISMA extensions may provide additional reporting guidance for particular review types or aspects of the review.

PRISMA-S provides additional guidance for reporting literature searches in systematic reviews.