Skip to Main Content
Banner Image
WNHS Internet |   WNHS Hub |  HealthPoint |   WA Health Library Sites
Contact Us!

Research: Finding the Evidence

Focus the Question

The first step in finding the evidence is to ask the right question!

Construct a clinical question to maximise your chances of finding meaningful information.

For example:

Your patient is a thirty year old woman, 14 weeks pregnant with her first child.  On an initial antenatal visit she is found to have a BMI of 32, putting her in the obese range.  You are concerned about the risk of adverse outcomes for the woman and her baby, especially if she gains a lot of weight during her pregnancy.  You wonder whether dietary or lifestyle interventions could help your patient limit her weight gain during the remainder of her pregnancy.


Use the PICOT formula to turn the scenario into a clinical question and identify the key points:

P = Patient or Population or Problem

"thirty year old woman, 14 weeks pregnant with her first child.....BMI of 32"

I = Intervention

"dietary or lifestyle interventions"

C = Comparison

usual care

O = Outcome

"limit her weight gain during pregnancy"

T = Type of study

Question = therapy; study type = RCT or systematic review

The next step is to translate the key points into keywords. 

"thirty year old woman, 14 weeks pregnant with her first child.....BMI of 32"

I "dietary or lifestyle interventions"

C usual care

O "limit her weight gain during pregnancy"

T Question = therapy; study type = RCT or systematic review


When considering keywords, choose terms that will find the information you need, without narrowing the search too much.  For example "BMI of 32" is too specific; "obese" would be a better term. 

Also consider synonyms, or alternative terms, to capture as many relevant articles as possible.  For example, alternative terms for "lifestyle intervention" could include "exercise" or "diet".

Next consider dropping some terms which may be redundant.  For example, if you include the term "pregnant" or "antenatal", the term "woman" isn't needed.  If the comparison is "usual care", you don't need to specify this in the keywords.

Finally, think how to form terms into an effective search strategy.  Combine alternative terms, or synonyms, with OR and terms for different concepts with AND.

The search strategy for this example would be:

obese OR overweight


pregnant OR pregnancy OR antenatal OR prenatal


lifestyle OR diet OR exercise


weight gain OR excessive weight

limit to Systematic Reviews or RCTs.


The table below explains how Boolean Operators (AND, OR, NOT) work

Tutorials on formulating a clinical question

The well-built clinical question: a key to evidence-based decisions. Richardson, WS. et al. ACP Journal Club, v123:A12, Nov-Dec, 1995.

Formulating Answerable Questions  CEBM University of Toronto

Find the Evidence

Where do I find the evidence?

The most efficient place to start searching is at the top of the '6S Hierarchy of Evidence' (see What is EBP?) and work down.  This way you start searching highly filtered resources which may be able to give you a quick answer to your query.  Only after checking these do you work your way down to the unfiltered resources containing single studies which will take time to appraise.  


Clinical decision-making tools, such as JBIBest Practice and Dynamed, offer synthesised and summarised evidence on many topics.  You may also find it useful to look at local and international guidelines, including the WNHS Guidelines and RANZCOG Guidelines as well as those from the Australian Clinical Guidelines Portal, the NICE Guidance and NICE Pathways (UK). Also see the Guidelines & EBP Resources tab.


If you do not find the answer to your query in the guidelines or clinical decision-making tools, you may be able to find a relevant systematic review.  The Cochrane Library provides access to systematic reviews, as does TRIP and the PubMed clinical queries search.


If your query relates to a less common topic, the evidence may not yet have been synthesised.  In this case you will need to use unfiltered resources to look for original studies and then appraise them yourself.  You will also need to find original studies if you are involved in research, or in producing or updating guidelines as filtered resources maynot include the very latest research.  Search the following databases to find quality single studies: MedlinePubMed; Emcare; PsycInfoEmbase.  For a complete list of relevant databases, this table gives examples of clinical questions matched with selected databases.