Searching for Evidence


In addition to the Five "A"s in evidence based healthcare, there are five steps to carrying out a search for evidence. Developing a search strategy will help you find what you're looking for. Defining the question is an important first step that feeds all other steps. When looking for research evidence you could think about the way research articles are constructed - this will help you construct your question:

  • the Sample or Group
  • the Setting
  • the Problem
  • what was done - Method or Intervention
  • the results or Outcomes

Step one: Asking the Right Question

Sometimes called the PICOT formula (see below), it is a useful way to construct focused questions, makes searching more structured, and increases the chance of finding an answer.


PICOT formula

Think about:

P: the patient's or populaton condition you're interested in

I: the intervention you're interested in (for example, test, drug, treatment)

C: a comparison if relevant (for example, placebo, standard care)

O: a patient-centred outcome.

T: Time

So the clinical question based on the first assumption would be:

In a patient with a suspected deep vein thrombosis (patient), can clinical examination (intervention) compared with a venogram (comparison) diagnose a deep vein thrombosis (outcome)?


Step two: What to Search

Step three: Carrying out your Search

Develop your Search Terms

Your search terms should be based on each component of your research question (PICOT)

Search termElderlyOral supplement Nutritional status 
Search termAgedFood supplement BMI 
Search termgeriatric  Nutritional assessment 
Search termOlder person  weight 
Search termResidential care    
Search termNursing home    


Refining your Search
The terms generated in step one are then used to build up a search strategy with the use of the Boolean operators (OR AND)
E.g. [(elderly OR aged OR geriatric OR older person) AND (residential care or nursing home)] AND [oral supplement OR food supplement] AND [nutritional status OR BMI OR nutritional assessment OR weight]

Different field are uses in the search engines such as keyword search advanced search and thesaurus or MeSH search; electronic search engines have tutorials which will bring you through the searching process. 

You can limit your search by language age bracket journal type, publication year etc, be careful that you do not exclude useful literature by the over use of limits


Step Four: Acquiring documents


Step Five: Follow up, Appraisal