Step 3. Free-Text Terms

Determine any alternative terms for the identified key concepts and add them to the Concept Table. It is important to enter as many potential terms as possible. Some authors may refer to the same concept using a different term. Important articles may be missed if not all relevant alternative terms are included in the search.

These free-text terms will be searched as textwords (words in title, abstract, author's keywords).

Search Strategy Template

Ideas For Brainstorming Free-Text Terms

• Conduct a simple search on the topic – look at words in titles, abstracts and author's keywords
  • Scan for synonyms, alternative spelling variants, acronyms, abbreviations, medical terms, laymen's terms, drug brand names, and alternative ways of ordering phrase words
• Initial literature scanning of core articles and/or similar systematic reviews – look at titles and abstracts and author's keywords
• Speak to an expert in the field / supervisor
• Subject headings need to be repeated as free-text terms
• Look at Entry terms, Used for terms, Related terms mentioned in the subject heading databases (e.g. MeSH, Emtree, CINAHL Heading databases) (see Step 4). Often one or a combination of a few words is enough to capture many entry terms.
• For an 'exploded' subject heading, include narrower subject headings found in the hierarchy as free-text terms
• Google or a dictionary may identify additional terms
• Check for existing search strategies, e.g. subject search filters (see Subject Search Filters)

Use Automation Tools

Text mining tools do a frequency analysis; they identify commonly appearing words in pre-identified relevant studies and may inform search term selection:

• WordFreq from Systematic Review Accelerator - single words and phrases (upload EndNote library with key studies saved as XML file)
• PubMed PubReMiner - good for single words (run PubMed search)
• TerMine - good for phrases

Example

This Concept Table lists alternative terms for the four concepts in our example. These terms were identified by scanning the titles and abstracts of retrieved articles of an initial basic search.

Study designs to be included: RCTs only (see Step 8)

See source of example

Subject Search Filters

There are various web sites listing search filters for subject searches. You may not want to fully rely on these search strategies, but rather use them as a starting point to gather ideas.

• Search blocks, BMI from Dutch Biomedische Informatie
• PubMed search strategies: a blog that shares PubMed search strategies. They are posted in the hope that others will benefit from the work already put into their creation and/or will offer suggestions for improvements.
• CareSearch, palliative care knowledge network, PubMed searches
• Flinders Filters, developed by Flinders University
• The Lowitija Institute: provides easy access to Aboriginal and Torres Strait Islander health literature on PubMed
• InterTASC Information Specialists' Sub-Group's Search Filter Resource
• Hedges Project from Mc Master University, Health Information Reserach Unit
• Health Sciences Search Filters, University of Alberta Libraries

If you use somebody else's search strategy, you should acknowledge this. For example, you could cite it in the methods section, where you broadly describe how you conducted the search. Then add it to the reference list like any other type of reference.