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Systematic Reviews in Health

Define your question with the PICO Framework

PICO Framework

The first step in performing a Systematic Review is to formulate the research question.   Without a well-focused question, it can be very difficult and time consuming to identify appropriate resources and search for relevant evidence. Practitioners of Evidence-Based Practice (EBP) often use a specialised framework, called PICO, to form the question and facilitate the literature search.1 PICO stands for:

  • Patient Problem, (or Population)
  • Intervention,
  • Comparison or Control, and
  • Outcome

PICO Framework










For Systematic Reviews an additional item, T is sometimes added to the framework.  The T can stand for :

  • Type of study (e.g. Randomised Controlled Trials), 
  • Type of question, (i.e. Therapy, Prevention, Diagnosis, Prognosis, Etiology), 
  • Type of study participants
  • Type of intervention
  • Type of outcome measure, or 
  • Timeframe.

When forming your question using PICO, keep the following points in mind:

  • Your Patient is a member of a population as well as a person with (or at risk of) a health problem. So, in addition to age and gender, you may also need to consider ethnicity, socioeconomic status or other demographic variables.
  • A Comparison is not always present in a PICO analysis.
  • Outcomes should be measurable as the best evidence comes from rigorous studies with statistically significant findings.
  • An Outcome ideally measures clinical wellbeing or quality of life, and not alternates such as laboratory test results.

PICO Elements Change According to Question Type (Domain)

When forming your question using the PICO framework it is useful to think about what type of question it is you are asking, (therapy, prevention, diagnosis, prognosis, etiology). The table below illustrates ways in which Problems, Interventions, Comparisons and Outcomes vary according to the type (domain) of your question.2

Writing Your Question Statement

Once you have clearly identified the main elements of your question using the PICO framework, it is easy to write your question statement.  The following table provides some examples.

Examples of PICO questions


1. Schardt, C., Adams, M. B., Owens, T., Keitz, S., & Fontelo, P. (2007). Utilization of the PICO framework to improve searching PubMed for clinical questions. BMC Medical Informatics and Decision Making, 7, 16. doi:

2. Fineout-Overholt, E., & Johnston, L. (2005). Teaching EBP: asking searchable, answerable clinical questions. Worldviews On Evidence-Based Nursing, 2, 157-160.