Q: How do we conduct a thorough literature search for a systematic review?
How to ensure that we have all available studies on the subject we are writing our systematic review on? How do we collect all relevant studies for the purpose of a thorough literature/systematic review?
An exhaustive literature search is the key to a high quality review article. There can be thousands of published articles on a particular topic and choosing the ones that are relevant for your study is not an easy task. In the case of a systematic review, searching for literature is part of the research methodology. The search will usually try to capture as much literature as possible, while inclusion and exclusion criteria will be used to reduce the amount of it. Documentation of the search will make the review work replicable for other researchers.
The literature search needs to be organized and systematic, and you should aim to balance the sensitivity of the search with the specificity. The sensitivity of a search refers to the number of potentially relevant articles that you find while specificity refers to how many articles are actually relevant. In a systematic review, you would not want to miss any potentially relevant article. Hence, the search needs to be very sensitive.
Go through your research question carefully and identify main elements which will help you choose your keywords effectively. Choose as many relevant databases as you can for your search. Your librarian may be able to help you with this. Use advanced search options such as Boolean operators, truncation symbols, etc. for each database. In addition to databases of published literature, look up databases of registered clinical trials for unpublished results. Your librarian will be able to help you access unpublished and grey literature on your topic. Make an exhaustive list of search terms. Use as many variations and synonyms of search terms as possible.
Here are a couple of articles that will give you more detailed guidance about this:
- Systematic review searching
- How to carry out a literature search for a systematic review: a practical guide