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London Metropolitan University

Physiotherapy

Systematic review and systematic searching

A systematic review is a type of literature review that is thorough and reproduceable.

Make use of the indexes of literature with the widest coverage available through London Met or for free, use as many keywords to describe your research topic as possible, and use subject headings where available.

Record your searches and results at each stage of the process and build your search up in steps. 

A systematic-type review that you will do as a student is done on a smaller scale than a published systematic review, so no need to include Google Scholar or grey literature sources.

Steps involved in writing a systematic review:

  1. Definition of the review question

  2. Writing, and approval, of the protocol

  3. Operation of the search strategy

  4. Study assessment

  5. Creation of meta-analyses

  6. Putting results of review into context

Please read The need for systematic reviews on nutrition and dietetics for details.


There is a practical guide to performing systematic reviews in a healthcare context provides a step-by-step approach for students and health professionals. Using free, open-source software to extract data and perform the necessary meta-analyses, this guide navigates the process of reviews, from study design and randomised controlled trials to interpreting results and reporting your findings.

Each chapter includes an overview, learning outcomes, and practice questions. Aimed particularly at those who do not have an extensive statistical background, it will help enable you to confidently perform high-quality systematic reviews.

Free download: https://bit.ly/438vzyU

What is the difference between a systematic review and a literature review?

Getting started - choosing databases:

You may want to include the following databases in your search. Most use three or more databases. See the A-Z of Library E-Resources for a description of each and to link through and start searching:

  • PubMed (includes MeSH - Medical Subject Headings)
  • The Cochrane Library (for RCTs and existing systematic reviews only, includes MeSH)
  • CINAHL Complete (includes CINAHL Subject Headings)
  • Web of Science
  • Trip Medical Database
  • SPORTDiscus
  • APA PsycINFO

Getting started - scoping searches:

Your first searches will NOT be systematic, but WILL help you to refine your research question, identify gaps in the research, and identify extra terminology for later searches. You may choose to scope only in one database rather than trying many.

The systematic searching and screening process (see the search recordings tab):

  • Scoping searches - see above.
  • Keyword searches - using synonyms or alternative keywords and building the search in stages, making sure you do Boolean AND and OR searches correctly until you've combined everything and got one set of search results.
  • MeSH/Subject Heading searches (where available) - carefully exploring and selecting appropriate subject headings and putting them together appropriately using Boolean techniques (as above), until you have one set of subject heading search results.
  • Combining final keyword results with final subject heading results using Boolean OR operator - this removes duplicates.
  • Applying filters that help you to find articles that meet your criteria - different filters available in different databases.
  • Exporting results from each database into a file or a reference management programme where you can see and remove any duplicates.
  • Screening by title and abstract and excluding items that clearly do not meet your criteria.
  • Identifying how to get access to the full articles - exclude any that you can't get at all (including through London Met, at the British Library, through the Sconul Access Scheme or via interlibrary loan requests).
  • Read full articles and exclude any that do not meet your criteria.

Recording your methods and results:

Record your methods and results at every stage of the process in preparation for writing up your methodology and record reasons for excluding studies. There are tools that can help you do this, such as saving searches with personal accounts in databases, or doing screenshots of your search history, or simply keeping a record in a Word document. Doing a simple Internet search for systematic review tools will show you the range of other tools available.

See the other resources section of this guide to find links to PRISMA for the PRISMA flow diagram.

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  1. Too few results?
    • Choose broader terms
    • Use more synonyms combined with OR
    • Use fewer keywords combined with AND
    • Use a large interdisciplinary database
    • Use specialist sources
    • Use a 'citation pearl' as a starting point
      • Cited reference searching is also called snowballing, citation pearl searching, and forward- or backward-searching.
      • The process builds on an article or other document you already know is relevant to your study – a “citation pearl”.
      • You can look through the list of cited references to go backward in time and follow up on the sources the authors used.
      • Use the “citation pearl” to go forward in time using a citation index. 
  2. Too many results?
    • Ask more specific questions
    • Choose more specific terms
    • Use fewer synonyms combined with OR
    • Use a subject database
    • Use subject headings if available
    • Set limits
    • Sort results