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Evidence Based Practice

Information to help find and appraise evidence-based resources.


Evidence-based practice uses the PICO model for formulating a searchable question:

P = Population/Problem

How would I describe the problem or a group of patients similar to mine?

I = Intervention

What main intervention, prognostic factor or exposure am I considering?

C = Comparison

Is there an alternative to compare with the intervention?

O = Outlook

What do I hope to accomplish, measure, improve or affect?


PICO helps you to break a clinical problem into important concepts and formulate a searchable question that can be answered with research.

1. Begin with a clinical problem:

  • Your patient is a young, active female athlete with a partial ACL tear in her right knee.  She would like to avoid surgery. 

2. Express the problem using PICO:


Athlete with partial ACL tear


Physical therapy




stable functioning knee


3. Formulate the problem as a research question:

  • In a young female athlete with a partial ACL tear, is physical therapy as effective as surgery?

Clarifying PICO

Question Type Patient Problem or Population   Intervention or Exposure Comparison or Control Example Outcome Measures
Therapy (Treatment) Patient's disease or condition. A therapeutic measure, eg., medication, surgical intervention, or life style change. Standard care, another intervention, or a placebo. Mortality rate, number of  days off work, pain, disability.
Prevention Patient's risk factors and general health condition. A preventive measure, e.g., A lifestyle change or medication. Another preventative measure OR maybe not applicable. Mortality rate, number of days off work, disease incidence.
Diagnosis Specific disease or condition. A diagnostic test or procedure. Current "reference standard" or "gold standard" test for that disease or condition. Measures of the test utility, i.e. sensitivity, specificity, odds ratio.

Prognosis (Forecast)

Duration and severity of main prognostic factor or clinical problem. Usually time or "watchful waiting". Usually not applicable. Survival rates, mortality rates, rates of disease progression.
Etiology (Causation) Patient's risk factors, current health disorders, or general health condition. The intervention or exposure of interest.  Includes an indication of the strength/dose of the risk factor and the duration of the exposure. Usually not applicable. Survival rates, mortality rates, rates of disease progression.


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.

Question Type   Patient Problem or Population Intervention or Exposure   Comparison or Control Outcome Measure
Therapy In patients with osteoarthritis of the knee is hydrotherapy more effective than traditional physiotherapy in relieving pain?
Prevention For obese children does the use of community recreation activities compared to educational programs on lifestyle changes

reduce the risk of diabetes mellitus?

Diagnosis For deep vein thrombosis is D-dimer testing or ultrasound more accurate for diagnosis?
Prognosis In healthy older women that suffer hip fractures within the year after injury   what is the relative risk of death?
Etiology Do adults    who binge drink compared to those who do not binge drink have higher mortality rates?


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

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.