Skip to main content

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:

  1. To verify that your question hasn't already been answered
  2. To verify that there are no other review protocols registered with researchers already looking at the same question
  3. 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

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review, key questions broken into PICO components, inclusion/exclusion criteria, literature searches for published/unpublished literature, data abstraction/data management, assessment of methodological quality of individual studies, data synthesis, and grading the evidence for each key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.

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.