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Research Skills for Health: Search Strategies and using PICO

Search Strategies and Frameworks

Once you have your question in mind, you can start to build your search strategy.  This involves:

  • Applying a framework like PICO / PICo to your question to organise your keywords
  • Finding the controlled vocabulary (such as MeSH) for these keywords from the individual databases you will be searching
  • Incorporating Boolean operators (AND OR NOT) and other search functions such as:
    • truncation
    • wildcards
    • phrase searching
    • field tags

PICO Searching

PICO searching is commonly used in health sciences to format an effective search strategy.  It helps you to focus and develop your clinical research question before you tackle the research itself.  It will typically stem from a scenario that requires further investigation. Depending on your topic or whether you are doing quantitative or qualitative research, you will need to determine the search framework that best suits your purposes, two commonly used ones are the PICO or PICo.  Links to others such as SPICE or SPIDER are also listed below.

  Quantitative   Qualitative
P Population, Patient or Problem P Population
I Intervention I Phenomenon of Interest
Comparison Co Context
O Outcome    

Population:  For this you will think about the patient, group of people, or problem you are concerned with.  The population of your research may be grouped by age, and/or gender, and/or ethnicity and/or condition/disease.

Intervention: The intervention looks at the intervention or treatment being considered.  If you are doing a qualitative study this would be your phenomenon of interest.

Comparison: Looks at whether there is an alternative treatment to compare again.  There may not be, it could mean comparing with not going through with a suggested intervention and/or comparing to a standard procedure.  If the comparison aspect does not fit with your research topic, you could relabel it as context to describe the location or area of health you are researching.

Outcomes: What are the expected outcomes?  What are you intending to achieve or improve?  What will it mean for your patient(s)? 

For example, if you were wanting to find out whether playing music could help ease pre operative anxiety in children, your PICO might look like this:

 

Population Intervention Comparison Outcome
Children about to receive surgery Music  usual care Reduced anxiety

You would then build this search further by adding additional keywords, controlled vocabulary, truncation  etc.

 

  Population Intervention Comparison Outcome
Keywords

Children, child*, pediatric, paediatric, infant, toddler, preschool

Preoperative, perioperative, peri-operative, pre-surgery, 

Music, "music therapy", "music intervention"  usual care anxiety, distress, "reduced anxiety", calm*, relax*, "anxiety reduction"

Controlled vocabulary 

(MeSH)

Child, pediatrics, "child, preschool", infant

"preoperative period", "preoperative care"

music, "music therapy"   anxiety

 

Applying your PICO question to a search strategy

The next step of your search strategy is to apply Boolean operators (AND OR NOT) and field tags (where in a document you want to search for your terms, title, abstract, keywords, main headings etc.).

If you write your strategy out like this, it will be easy to add into your protocol and also you can then use copy and paste it into the database search boxes.

When doing systematic reviews, it is advisable to write out and search the controlled vocabulary terms separately as these can differ across databases and can affect your search results (see the free text vs controlled vocabulary box on the right).

Concept 1: Child

[Title / abstract]  

Children OR child* OR pediatric OR paediatric OR infant OR toddler OR preschool

[Controlled vocab: Main Heading / MeSH]

Child OR preschool

Concept 2: Preoperative

[Title / abstract]  

Preoperative OR perioperative OR peri-operative OR pre-surgery OR "preoperative period" OR "preoperative care"

[Controlled vocab: Main Heading / MeSH]

"Preoperative period" OR "preoperative care"

Concept 3

[Title / abstract]  

Music OR "music therapy" OR "music intervention" 

[Controlled vocab: Main Heading / MeSH]

Music OR "music therapy"

Concept 4

[Title / abstract]  

Anxiety OR distress OR "reduced anxiety" OR calm* OR relax* OR "anxiety reduction"

[Controlled vocab: Main Heading / MeSH]

Anxiety

Turning it into a search string

If you are doing a general search for information, you can just use the controlled vocabulary terms as part of your search string, so your search might look like:

(Children OR child* OR pediatric OR paediatric OR infant OR toddler OR preschool) AND (Preoperative OR perioperative OR peri-operative OR pre-surgery OR "preoperative period" OR "preoperative care" AND (Music OR "music therapy" OR "music intervention" AND (Anxiety OR distress OR "reduced anxiety" OR calm* OR relax* OR "anxiety reduction")

 

If you are doing a systematic search, you will need to separate them out as different databases use different thesauri/subject headings so you'll need to adapt the terms for each one.  A systematic search string might look like this. (Note:  In PubMed I've found that you need to put  [MeSH Terms] after each MeSH term rather than just using the drop down menu, otherwise it only searches one term as MeSH and the rest as All Fields - also, when you add the field tag in brackets afterwards, it is easier to copy and paste in rather than use the drop down menu each time.)

Database: PubMed.

Search # Field Tag Key words Results
1 Title / Abstract Children OR child* OR pediatric OR paediatric OR infant OR toddler OR preschool  
2 MeSH Child [MeSH Terms] OR "Child, Preschool" [MeSH Terms]  
3   S1 OR S2  
4 Title / Abstract Preoperative OR perioperative OR peri-operative OR pre-surgery OR "preoperative period" OR "preoperative care"  
5 MeSH "Preoperative Period" [MeSH Terms] OR "Preoperative Care" [MeSH Terms]  
6   S4 OR S5  
7 Title / Abstract Music OR "music therapy" OR "music intervention"  
8 MeSH Music [MeSH Terms] OR "music therapy" [MeSH Terms]  
9   S7 OR S8  
10 Title / Abstract Anxiety OR distress OR "reduced anxiety" OR calm* OR relax* OR "anxiety reduction"  
11 MeSH Anxiety  [MeSH Terms]  
12   S10 OR S11  
13   S3 AND S6 AND S9 AND S12  
14   Add filters such as date range, language, etc.  

 

Other Frameworks - Links

Methley, A. M., Campbell, S., Chew-Graham, C., McNally, R., & Cheraghi-Sohi, S. (2014). PICO, PICOS, and SPIDER: A comparison study of specificity and sensitivity in three search tools for qualitative systematic reviews. BMC Health Services Research, 14(1), 579–596. https://doi.org/10.1186/s12913-            014-0579-0

Boolean Operators

 

AND - Narrows your search to find documents that have both 'this' term AND 'that' term.

ORExpands your search to include a variety of similar terms e.g. teenager OR adolescent OR youth

NOT - narrows your search to remove documents that may be related to your search but not relevant to what your research is looking for e.g. surgery NOT veterinary 

Some databases require these terms to be in uppercase, so it good to get into the habit of always using upper case for these terms.  (You don't need to in OneSearch)

Search tips and tricks

Truncationuse an asterisk (*) after a stem term to expand your search e.g. behav* should search for behaviour, behavior, behaviors, behavioral etc.

Phrase searchingput quotation marks around a group of words that you would like to search as one term.  It helps to narrow your search, e.g. instead of music therapy (which will search for music and therapy as separate terms) try "music therapy".

Brackets - it can be useful to group your search terms into brackets, particularly when using engines with only one search bar e.g. (child* OR preschooler or infant) AND (preoperative or surgery) AND (music OR "music therapy) AND (anxiety OR distress)

Free text vs Controlled Vocabulary

Why is it useful to search both free text and controlled vocabulary?

Controlled vocabulary (also known as subject headings or thesaurus) refers to the terms that have been attached to a document in a database.  Indexers read the documents and select the best terms from a predetermined list of words that best describes the topics of an article.  So for example if you are searching PubMed, which uses the Medical Subject Headings (MeSH), if an article has been written about heart attacks, it will always have the term myocardial infarction attached to it.

Using controlled vocabulary can ensure that you are using the best term that will find all articles associated with your topic.

However, it is still useful to also search free text keywords (such as "heart attack") as:

  • Different databases used different controlled vocabulary.
    • When searching systematically it is useful to demonstrate these differences and helps you to adjust your 
  • New articles may not have been indexed yet, so if you were to only use the MeSH terms, you may miss new research.
  • There may not be a subject heading for the concept you are researching.
  • Some newer words (e.g. augmented reality) may have only been added to the thesaurus recently and won't search articles on the topic that were indexed prior to this.
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