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Literature Search Process
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1. Develop a sensitive search strategy to retrieve all possible relevant studies
- Identify relevant search terms, their synonyms and variants, and related MeSH (PubMed) or Emtree (EMBASE) terms
- Logically combine search terms using Boolean operators (e.g., AND, OR)
- Use applicable search field qualifiers or filters
- Inspect search results and get feedback from team members
- Refine the search strategy
- Inspect search results and make further refinements to the search strategy as needed
2. Translate the search strategy for other databases
3. Document the search process for each database including final search strategy, date of search, and number of retrieved studies. Consult PRISMA for the type of information that should be recorded.
Information Sources
Multiple databases must be searched to ensure comprehensive results and to reduce bias. The most pertinent databases for the health sciences include:
- MEDLINE/PubMed (biomedical)
- Embase (biomedical)
- Cochrane Library (clinical)
- Scopus (life sciences, social sciences, physical sciences, and health sciences)
- Web of Science (multidisciplinary)
- CINAHL Complete (nursing and allied health)
- ERIC (education)
- PsycINFO (psychology)
Grey literature is documents produced by organizations (e.g., governments, academics, businesses, industry) outside of the traditional commercial or academic publishing and distribution channels. Grey literature includes reports, white papers, conference abstracts, presentations, proceedings, dissertations and theses, patents, regulatory information, and policies and procedures.
Other strategies for finding relevant studies:
- Review reference lists of included studies
- Handsearching: manually scan tables of contents of selected journal(s)
- Scan abstracts presented at selected conference(s)
- Search Google or Google Scholar
Identifying MeSH and EMTREE Terms
- MeSH DatabaseNLM controlled vocabulary thesaurus used for indexing articles for PubMed
- Yale MeSH AnalyzerTool for identifying related MeSH terms
- EMTREE termsEmbase controlled vocabulary thesaurus
Example PubMed search strategy
(amputee[tiab] OR amputees[tiab] OR amputees[MeSH] OR amputation[tiab] OR amputation[MeSH] OR “amputation, traumatic”[MeSH] OR “limb loss”[tiab]) AND (leg[tiab] OR legs[tiab] OR “lower extremity”[tiab] OR “lower extremity”[MeSH] OR “lower limb”[tiab] OR transtibial[tiab] OR transfemoral[tiab] OR “below knee”[tiab] OR “above knee”[tiab]) AND (“energy expenditure”[tiab] OR “physical activity”[tiab] OR “physically active”[tiab] OR “activity level”[tiab] OR “activity levels”[tiab] OR “activity monitor”[tiab] OR “activity monitoring”[tiab] OR accelerometry[tiab] OR accelerometer[tiab] OR “physical performance”[tiab] OR “step count”[tiab] OR pedometer[tiab] OR “ambulation monitoring”[tiab] OR “body-worn sensor”[tiabs] OR “community mobility”[tiab])
" " = phrase search
[MeSH] = search for word/phase as a MeSH term
[tiab] = search for word/phase in the title or abstract
Search filters
Using a search filters/hedges (i.e., a pre-tested collections of search terms designed to retrieve specific types of records) may help identify studies on particular topics or employing particular study designs. Search filters can be designed to maximize either search sensitivity or search precision.
Below are sources of filters that have been tested against gold-standard sets of bibliographic records.
- PubMed’s Clinical Queries and Health Services Research Queries
- CINAHL home page with Clinical Queries and Publication Type filters
- McMaster University Search Filters for Medline, Embase, and PsycINFO in OVID syntax
- Cochrane Handbook Section 6.4.11: Search Filters
- The InterTASC Information Specialists' Sub-Group Search Filter Resource
- Methodology Filters by Countway Library of Medicine (Harvard)
- SIGN (Scottish Intercollegiate Guidelines Network) filters page
- Blog: PubMed Search Strategies