Students: please read
This guide explains the full systematic review process. If you are a student working on a systematic review assignment you may have been given particular instructions (perhaps assigned a topic) or limits (perhaps given guidance on the sorts, or number, of studies you should review). If you are in any doubt about the specific terms of your assignment please seek clarification from your marker.
What is a systematic review?
A systematic review "attempts to identify, appraise and synthesise all the empirical evidence that meets pre-specified eligibility criteria to answer a given research question. Researchers conducting systematic reviews use explicit methods aimed at minimising bias, in order to produce more reliable findings that can be used to inform decision making” (Cochrane Collaboration 2011 section 1.2.).
In basic terms:
- A systematic review is conducted to find the answer to a pre-determined research question.
- It may concern an area of doubt - for example, studies may have produced contradictory results as to the most effective treatment or drug for a disease or the benefits or lack thereof of a therapy.
- The reviewer (or review team) decides the review question and any inclusion or exclusion criteria (perhaps only studies within a particular time frame are to be included, or only randomised controlled trials (RCTs) etc.).
- The review process is clearly set out before work begins (usually in a protocol) so that it can be easily repeated, is transparent and reduces the risk of bias in the search for, selection and interpretation of relevant studies.
- A rigorous search is conducted to identify all relevant studies whether published or unpublished.
- Studies are screened to see if they should be included or excluded from the review based on the terms of the review and inclusion or exclusion criteria.
- Studies which are to be included are assessed for quality.
- They are then synthesised, analysed, interpreted and reported in a written review.
(adapted from Hemingway and Brereton 2009)
Systematic reviews and evidence-based practice
Evidence based practice in health and social care combines:
- the systematic search for, and application of, the best evidence available on a particular area of practice
- the expertise and experience of the practitioner in the relevant field (whether that practitioner is a nurse, pharmacist, physiotherapist, occupational therapist, nutritionist, radiographer, social worker, psychologist or doctor)
- the patient or service user's values and preferences
with the aim of providing the best possible care or service for the patient or service user.
Literature in this area may examine the "hierarchy of evidence". Systematic reviews, which require a rigorous search for, synthesis and analysis of studies on the same topic, sit at the top of the hierarchy. They represent the best evidence available in relation to a particular research question.
(figure adapted from Glover et al. cited by University Of Pittsburgh. Health Sciences Library Systems 2016)
What is a meta-analysis?
Some versions of the "hierarchy of evidence" place meta-analyses at the top. A meta-analysis is a statistical method for combining the numerical results of studies. A meta-analysis may follow a systematic review and comprise statistical analyses of the combined research data from the various studies included in that systematic review (see Crombie and Davies (2009) for an in-depth discussion).