Comprehensive search
Learning Objectives
This sub-chapter will help you:
- translate your search to run it on different databases.
- find grey literature.
- track citations of your included articles.
“…all identified keywords and index terms should then be undertaken across all included databases.” (Peters et al., 2020, 11.2.5)
Now you have created your search strategy, it is time to run it in each database you chose in the protocol. It should be identical in each database apart from subject headings and operators. This can be a lengthy process and needs to be documented to be reported. You will also search for grey literature if you are including it. The results retrieved will be the ones you screen for inclusion in your review.
Search translation
Each database has unique operators and subject headings. It is not possible to use an identical search in different databases without translating the strategy. You will need to alter:
- subject headings: These need to be from the thesaurus of the database being searched. Some such as Scopus and Web of Science do not use subject headings, so they need to be turned into keywords.
- field codes: These codes tell the database where to look for your terms and are different in each database.
- operators: Advanced search features such as wildcards are often different in each database.
To translate your search, use the document you have recorded your search in. Copy and paste the full search strategy, and then manually edit the parts that need changing to fit each different database.
Alternatively, you can make use of a tool to automatically translate your search.
- Polyglot: A tool by the Evidence Review Accelerator (TERA). Enter your search strategy for PubMed or Ovid MEDLINE, and it will be translated for several different databases. It will not change the subject headings, so you need to find the appropriate subject headings for each database yourself.
Grey literature
Grey literature is not commercially published and is often by governments, organisations, or businesses. It is increasingly included in searches for reviews, as it minimises publication bias and applies research to practice and policies. It can be challenging to find because there is no one place to find it all. With care and planning, you can search and report on grey literature systematically.
Depending on your discipline or question, you may need to search for:
- clinical trial registrations or data
- conferences
- theses and dissertations
- association reports
- government reports
- stakeholders, for example, non-government organisations, corporations, etc
- statistics or data
- technical reports, standards, patents
- clinical guidelines
- pre-prints
- repositories
- blogs and social media posts
You can search for grey literature in different ways:
- grey literature databases: ProQuest Dissertations and Theses, Web of Science Proceedings Citation Index, Analysis & Policy Observatory, preprint servers, etc.
- hand search grey literature from primary sources: Look in the reference lists of relevant peer reviewed articles.
- websites of key organisations or government departments: The search features are usually basic.
- web search: Conduct an advanced Google search, or search Google Scholar as it includes material in repositories that is not found in regular databases.
Google and Google Scholar tips:
- “double quote marks” finds phrases in the exact order required, e.g., “mental health”
- a pipe mark works like OR as it finds any of the terms, e.g., anxiety | stress | worry
- a dash mark works like NOT as it will exclude a term, e.g., depression -anxiety
- #..# two dots between years will give a date range, e.g., 2019..2024
- site: limits results to a site, e.g., depression site:gov.au
- filetype: limits to a particular file type, e.g., “mental health” filetype:pdf
While this search may not be as systematic as your database search, you can still report your strategy. Record the source, the date searched, the terms used, and how many results were found, with any adjustments or alterations described. For example, if you did an advanced Google search, record how you decided when to stop screening results, such as after three pages with no relevant results.
Activity 10
Have a go at searching for grey literature on the research question:
- Is a whole language or phonics-based approach more effective for remedial literacy development in primary school children?
Try the following sources:
Think about:
- Did you find anything relevant?
- How challenging or easy was it to find?
- Is there anywhere that may have also been suitable to search?
Citation tracking and hand searching
This stage is done after screening with only the included articles to double check you have not missed anything.
The tables of contents of relevant journals can be searched to see if there are additional articles that meet the criteria, discipline experts can be asked if they know of any additional articles, or citation tracking tools can be used.
Regardless of the manner of hand searching, any additional articles found need to be reported.
When hand searching, often only the reference lists are examined to see if there are any more potentially relevant articles that can be included. However, it is advisable to also track citations forward to see if there are newer articles that have cited the included articles.
Several useful tools assist in tracking citations forward and backward:
- SpiderCite: finds articles in the reference lists of included articles as well as newer, citing articles.
- Research Rabbit: set up collections of articles and see the connections between related articles and authors.
- Citationchaser: see references and citations of an article set, as well as analyse and view them as a visual network.
Activity 11
Go to Citationchaser. Go to Article Input in the top menu and copy and paste the following PubMed IDs for articles about parental stress during COVID-19 into the correct field.
- 32859394, 33182661, 33930664, 36480384
Now click on Load my input articles. You can now click on References and Citations in the top menu, then Search for all articles. Look at some of the references and the articles citing the input articles to see if they could be relevant to the question.
Example
Click on the button below to see an example of the CINAHL (EBSCOhost) search strategy for the following systematic review.
Sullivan, O., Curtin, M., Flynn, R., Cronin, C., Mahony, J. O., & Trujillo, J. (2024). Telehealth interventions for transition to self-management in adolescents with allergic conditions: A systematic review. Allergy, 79, 861-883. https://doi.org/10.1111/all.15963
Further reading
Paez, A. (2017). Gray literature: An important resource in systematic reviews. Journal of Evidence-Based Medicine, 10(3), 233-240. https://doi.org/10.1111/jebm.12266
References
Peters, M. D. J., Godfrey, C., McInerney, P., Munn, Z., Tricco, A. C., & Khalil, H. (2020). Scoping reviews. In E. Aromataris, & Z. Munn (Eds.), JBI manual for evidence synthesis. https://jbi-global-wiki.refined.site/space/MANUAL/355862497/10.+Scoping+reviews
A systematically organised collection of information, such as journal articles.
A word or phrase that describes all material in a database on that subject.
A character or string of characters used in a database to narrow the focus of the search.
Material that is not published in a peer reviewed journal or a chapter in a book. It includes internal reports, committee minutes, conference papers, fact sheets, newsletters.
The process of checking the eligibility of studies found in the search
A presentation of all the sources used in a piece of writing.
A reference to a source that gives enough information so the reader can find the source.
