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PubMed (English): Step 1 - Research question + PICO

Step 1 - Formulating your research question

Before searching formulate a good and clear clinical question. This is often underestimated. It is tempting to start searching immediately and type some terms in the search bar. Unfortunately the result is mostly unsatisfactory: too many irrelevant hits.
The question should be formulated to be able to find an answer.

Splitting the research question

Do you have a good research question?
Split it into sub-elements.
You can do this by using:

  1. PICO-method
  2. Building block method


By reframing your research question into PICO-elements you are forced to think ahead of the outcome you want.

P = patient / population / problem
I = intervention
C = comparison
O =


It is not necessary to use all the PICO elements. Sometimes only P and I will do. Firstly, search each PICO-element. Search for matching search terms and think of possible synonyms.Then combine the PICO elements. Use the right search terms and the combination will give you an answer to your research question..



I - Only 1 intervention per PICO is allowed. More interventions: more PICO's.
C - Not very common. A lot of researches are already comparative studies. Only use C if you want to compare two different therapies.
O - Is your outcome the effect of an intervention? Then do no use O, choose RCT as publication type.
M -

It may be relevant to add method (RCT, systematic review) or domain (therapy, diagnosis, prognosis) to your PICO. See also tap Step 5 - Filters & Clinical Queries.

Building block method

It is not always possible to make a PICO of your research question. Then use the building block method. The principle is the same as PICO. Use the main elements of your question (building blocks). Search matching search terms per element and add synonyms. In the end you combine the elements. | Disclaimer | Over Zuyd Bibliotheek