A good literature review requires a comprehensive literature search, identifying all relevant research articles that best addresses your research question. It is important to structure your literature search systematically; clearly identify the scope before you begin and keep in mind the quality and relevance of the literature as you proceed.
Begin your search strategy by using the PICO framework below:
Structuring your question will clarify the search and identify keywords or search terms that will assist with your search.When conducting a search within a large database your search terms should be closely related to the components of your PICO question. For more information see the Tutorial on the right.
You want to conduct a literature review that asks the question:
For an adult with lower back pain, is exercise or resting a more effective treatment?
P - Adult with lower back pain
I - Exercise
C - Rest
O - Relief of lower back pain
When conducting a systematic search for a literature review it is best to find all the synonyms you can on your keywords, such as lower back pain, lower backache
Join the synonyms together using OR eg. lower back pain OR lower backache
Joining Concepts Together for the Database Searching
Use AND to join the main concepts together
lower back pain OR lower backache
exercise OR physical activity
Using the Limits or Filters within the databases helps define the scope of the literature review - for example is the focus on children or all recent literature that has been published in the last 5 years.
For the above example a limit to "All Adults" can be used.
Build a Search using MeSH
MeSH is the National Library of Medicine's controlled vocabulary thesaurus. Headings within the thesaurus are arranged in a hierarchical structure known as a "tree" that enables searches to be conducted at various levels of specificity. MeSH thesaurus can help find words used by indexers for medical concepts. This thesaurus works in the background of Medline by linking synonym.
Conducting a thorough search to identify relevant studies is a key factor in minimizing bias in the review process. The search process should be as transparent as possible and documented in a way that enables it to be evaluated and reproduced. It is best to search multiple databases when looking for research and to also document how you conduct your search in the Methods section of your literature review.
What articles you include and exclude is determined by the goals, coverage and context of the research question. This inclusion / exclusion criteria must be made explicit in the Literature Review. For example, you might include or exclude according to:
1. The right Type of study for your review question? e.g. Randomized Control Trials; case studies,cohort studies
2. Publication timeframe e.g. 2006-2016
3. Population or patient group
4. Significant sample size
5. Published in English
The PRISMA (Preferred Reporting Items for Systematic Review and Meta-analysis) flow diagram has been developed specifically for Systematic Reviews. It allows the author to visually depict what articles have been identified and how articles have been screened for eligibility. You can adapt this flow chart to help you depict and articulate how you have arrived at the final set of articles to review.
The PRISMA Statement is the gold standard for conducting and reporting a systematic reviews. Along with the flow chart, the site also provides a helpful checklist for developing a Protocol which sets out what databases have been searched, the inclusion and exclusion criteria, search terms defined, method to analyze the data etc. It is a tool to provide transparency to your literature review and may be required when submitting your article for publication. Again, it has been designed for Systematic reviews, but you can adapt the checklist to your own literature review.
Moher, D., Shamseer, L., Clarke, M., Ghersi, D., Liberati, A., Petticrew, M., & ... Stewart, L. A. (2015). Preferred reporting items for systematic review and meta-analysis protocols (PRISMA-P) 2015 statement. Systematic Reviews, 41. doi:10.1186/2046-4053-4-1
To generate a PRISMA flow diagram from a csv file use this handy tool created by Neal R Haddaway and Luke A McGuinness
Flow charts can be referenced using the following citation:
Neal R Haddaway, Luke A McGuinness. (2020). PRISMA2020: R package and ShinyApp for producing PRISMA 2020 compliant flow diagrams (Version 0.0.1). Zenodo. http://doi.org/10.5281/zenodo.4287835