This guide is intended for students and researchers at the University of Oxford and staff in Oxford University Hospitals Trust seeking up to date information on how to carry out systematic reviews.
Use this guide to find out about this research technique and learn where to go for more help.
If you are planning to carry out a systematic review, it is worth contacting your outreach librarian (medical sciences and NHS staff and students) or subject librarian (other disciplines) at the start. They can help advise you on all aspects of the review process and in some cases work with you on the review directly.
*Coming soon, further information on data extraction, risk of bias and writing up. Please ask your outreach librarian for help in the meantime.
A systematic review is a high-level overview of primary research on a particular research question that tries to identify, select, synthesize and appraise all high quality research evidence relevant to that question in order to answer it.
Systematic reviews are an approach used in health, education and social policy (as part of evidence based policy or practice). It's much more than a literature review - it follows a strict methodology which means it's transparent, rigorous and replicable.
Systematic reviews are a resource intensive research project as they require collaboration between a group of subject and methodological experts and involve a significant time commitment. The Cochrane Handbook recommends that screening of studies for inclusion, data extraction and quality should be conducted independently by at least two individuals.
In recent years, the field of evidence reviews has evolved, and the systematic review is just one type of evidence review within a broader family of reviews that follows a rigorous and transparent methodology. The methods we describe in this guide are applicable to a greater or lesser extent to systematic reviews, scoping reviews, rapid reviews, qualitative evidence syntheses, mapping reviews and realist reviews.
The process includes:
1. Formulating a question
2. Preparing and registering a protocol (research plan)
3. Searching for studies
4. Selecting studies according to predefined inclusion / exclusion criteria
5. Extracting data from included studies
6. Undertaking a quality assessment (Risk of Bias) assessment of included studies
7. Synthesising the evidence from included studies
8. Writing up methods and presenting conclusions / recommendations
As outlined above, a systematic review will address a specific question and use replicable and transparent methods in identifying, selecting, appraising and synthesizing the evidence. Literature reviews are more likely to provide overviews of a topic area and will use iterative methods in the process.
As the purposes of the reviews are different, many would advocate that narrative reviews have a place in providing a critical reflection and promoting greater understanding of developments within a field of research. If you’re new to a field, then a traditional literature review can be a valuable first step. The methods for searching the literature in this guide are still applicable, but there’s no expectation to identify all the research on your question, to have pre-defined inclusion/exclusion criteria, to conduct a quality assessment or to report your search methods in detail.
As discussed above, the type of review chosen can be influenced by the reason for conducting the review. Additional factors can also influence the choice; some examples given below:
Systematic reviews:
Health Care - Cochrane Handbook for systematic reviews of interventions & Cochrane Methods Groups for amongst others, reviews of Diagnostic Test Accuracy, Prognosis & Qualitative Research
Education, Social Care, Social Policy, Crime & Justice and International Development - Campbell Collaboration and EPPI-Centre
Environmental Sciences - Collaboration for Environmental Evidence
Scoping reviews - Joanna Briggs Institute
Rapid Reviews - Cochrane Methods Group: Rapid Reviews
Realist Reviews & Meta-Narrative Evidence Synthesis - RAMESES
Contact our team of Outreach Librarians for help with anything in this guide.