Systematic Review: Preparing for a Systematic Review

This guide presents tools and advice for conducting systematic reviews.

Searching for Existing systematic Reviews

Once you have defined your question you can start the searching process. The first step in searching for studies is to locate previously conducted systematic reviews in your area of interest. This has three main purposes:

To verify that your question hasn't already been answered
To verify that there are no other review protocols registered with researchers already looking at the same question
To identify related systematic reviews that will need to be accessed so that you can review the reference lists for relevant primary studies.

Useful databases for identifying systematic reviews

Cochrane Collaboration
The Cochrane Collaboration is a not-for-profit organisation with collaborators from over 120 countries working together to promote evidence-informed health decision-making by producing high-quality, relevant, accessible systematic reviews and other synthesised research evidence.
Campbell Library
The Campbell Collaboration maintains and disseminates systematic reviews in education, crime and justice, social welfare and international development.
PROSPERO
PROSPERO is an international database of prospectively registered systematic reviews in health and social care. Key features from the review protocol are recorded and maintained as a permanent record. PROSPERO aims to provide a comprehensive listing of systematic reviews registered at inception to help avoid unplanned duplication and enable comparison of reported review methods with what was planned in the protocol.
PubMed Clinical Queries
Clinical Queries offers a user-friendly approach to evidence-based searching on the Medline database.
Database of Abstracts of Reviews of Effects (DARE)
The Database of Abstracts of Reviews of Effects (DARE) contains details of systematic reviews that evaluate the effects of healthcare interventions and the delivery and organisation of health services. DARE also contains reviews of the wider determinants of health such as housing, transport, and social care where these impact directly on health, or have the potential to impact on health.
Epistemonikos
Epistemonikos is a collaborative, multilingual database of health evidence. It is the largest source of systematic reviews relevant for health-decision making, and a large source of other types of scientific evidence.
JBI Evidence Synthesis
JBI Evidence Synthesis seeks to disseminate rigorous, high-quality research that provides the best available evidence to inform policy and practice through the science and conduct of systematic and scoping reviews.

Develop your Protocol

At the outset of the review you need to develop a protocol outlining the study methodology. The protocol should include the rationale for the systematic review, key questions broken into PICO components, inclusion/exclusion criteria, literature searches for published/unpublished literature, data abstraction/data management, assessment of methodological quality of individual studies, data synthesis, and grading the evidence for each key question. You can locate existing protocols using the resources below.

PROSPERO
PROSPERO is an international database of prospectively registered systematic reviews in health and social care. Key features from the review protocol are recorded and maintained as a permanent record. PROSPERO aims to provide a comprehensive listing of systematic reviews registered at inception to help avoid unplanned duplication and enable comparison of reported review methods with what was planned in the protocol.
Cochrane Collaboration
The Cochrane Collaboration is a not-for-profit organisation with collaborators from over 120 countries working together to promote evidence-informed health decision-making by producing high-quality, relevant, accessible systematic reviews and other synthesised research evidence.
Campbell Collaboration
Guidelines for producing a Campbell Systematic Review. The Campbell Collaboration is an international research network that produces systematic reviews of the effects of social interventions.

Inclusion/Exclusion Criteria

Inclusion/Exclusion Criteria

You need to identify the criteria that will be used to determine which research studies will be included. These inclusion and exclusion criteria must be decided before you start the review. This is to ensure that your search targets articles that will provide an answer to your review question, allowing you to exclude any irrelevant ones. Criteria that should be considered include:

Type of studies
It is important to select articles with an appropriate design for the research question.

Type of participants
If focusing on a patient population, it is important to define their age, gender, diagnosis, as well as any other relevant factors.

Types of intervention
Describe the intervention that you are investigating. You may want to consider whether to include interventions carried out all over the world or just in the UK. The Cochrane Collaboration recommends finding all available studies from all over the world. As before, the interventions that are to be excluded may also need to be described here.

Types of outcome measures
Outcome measures usually refer to measurable outcomes or ‘clinical changes in health’. For example, these could include body structures and functions like pain and fatigue, activities as in functional abilities and participation or quality of life questionnaires.

Adapted from Bettany-Saltikov, J. 2010, "Learning how to undertake a systematic review: part 1", Nursing standard, vol. 24, no. 50, pp. 47.