Evidence-based models use a process for framing a question, locating, assessing, evaluating, and repeating as needed. PICO (T) elements include: Problem/Patient/Population, Intervention/Indicator, Comparison, Outcome, and (optional) Time element or Type of Study.
1. Frame the question: write out your information need in the form of a question, for example:
The question above includes the PICO elements:
|P (Problem or Patient or Population)||hospital acquired infection|
|I (intervention/indicator)||hand washing|
|C (comparison)||no hand washing; other solution; masks|
|O (outcome of interest)||reduced infection|
2. Plan a search strategy by identifying the major elements of your question, and translate natural language terms to subject descriptors, MeSH terms, or descriptors.
TIP: As you conduct an initial scoping search, start with the P and the I only and keep initial search results broad:
|natural language||term mapped to database vocabulary|
=hospital acquired infection
cross infection [MeSH]
cross infection [CINAHL]
|I (intervention/indicator)=hand washing||
hand disinfection [MeSH]
A simple database search strategy should begin with the P AND I:
cross infection AND (Handwashing OR Hand disinfection)
Start with both CINAHL and Medline/PubMed as initial article databases for a scoping search for most health sciences questions. If your topic has a behavioral/mental health component, also try PsycINFO.
3. After viewing the initial search results you may decide to narrow your search with terms for the Comparison, Outcome, Time factors or Type of study. Or you may view results, abstracts, and full text of articles to view the comparison and outcome elements. Use database filters, explained in Filtering the Evidence.
Need more help? Link to:
Retrieving too few articles? Below are ways to expand (broaden) your search:
health care reform bill OR health care bill OR (Patient Protection and Affordable Care Act) OR Affordable Care Act OR PPACA OR Health Care Reform/legislation & jurisprudence [MeSH] OR Obamacare
o In CINAHL, use the CINAHL Headings link to explore the tree structure of terms; EXPLODE to include narrower terms
o In PubMed, do a search using the MESH dropdown option; explore the tree structure of terms; using a broader term automatically EXPLODES to include narrower terms
o In PsycINFO, click on Search Tools, Thesaurus; explore the tree structure of terms; EXPLODE to include narrower terms
o Truncation symbols in a database, such as * or ? allow you to search on a root word and include plurals
- Diab* (to retrieve diabetes, diabetic, diabetogenic)
- Autis* (to retrieve autism, autistic)
- Nurs* (to retrieve nurse, nurses, nursing, etc.).
o Warning! Truncation may also retrieve false hits. A search on nurs* retrieves “nursery school”
Retrieving too many articles? Below are ways to narrow a search:
Narrow with subheadings (restrict your search to a subtopic of interest)
e.g., in PubMed: Hand hygiene/standards
- LIMIT by article type/publication type, by level of evidence (link to screenshots on limiting)
- Are you looking for an overview of a topic? "Review" articles synthesize a review of the literature that an author conducts at a certain point in time. A good quality review article may provide a useful overview and starting point.
- LIMIT by Age group if appropriate.
- LIMIT results by year of publication, language, etc.
o PubMed Clinical Queries http://www.ncbi.nlm.nih.gov/sites/pubmedutils/clinical (PubMed research methodology filters are explained here)
o CINAHL Clinical Queries (click on “Show More, Search Options, to locate limits for clinical queries filters)