As a clinician, you perform diagnostic tests, provide information on prognosis, and implement interventions on a daily basis. You may want to find out if the diagnostic test (or combination of tests) you are using is the best available considering your facilities and resources. You may want to discover the course of recovery for a condition you don’t see very often. You may also like to know if you are offering intervention that is supported by the results of high-quality research. To do these you need to pose a clinical question.

In order to answer your clinical question, it is helpful to break it down into 4 essential components, using the ‘PICO’ framework. In this memory aid, P stands for patient, problem or population, I stands for intervention, C stands for comparison or control intervention, and O stands for outcome. Taking the time to clearly define the question will help you work out the best search terms to use, which in turn will make finding the best research to answer your question less daunting or time-consuming.

For questions about the effects of interventions, your PICO question should include all 4 elements:
P (patient, problem or population): what is the condition or population group of interest, are you interested in a particular subgroup (eg, acute stroke) or sociodemographic group (eg, workers)? Are you working with older people, children, athletes, people that have had a traumatic brain injury or stroke?
I (the intervention): what treatment are you interested in.
C (the comparison or control intervention): are you interested in comparing your intervention to placebo, usual care, or another intervention (eg, aquatic versus land-based exercise).
O (the outcome): what measurable outcome(s) are you interested in improving? Is the outcome important to patients? Outcomes could be events (eg, falls), symptoms (eg, pain), functional measures (eg, walking speed) and quality of life. Harmful effects and the cost of treatment are also important outcomes to consider.

An example of a PICO question about the effects of intervention is: ‘In older people with knee osteoarthritis, is hydrotherapy more effective than land-based exercise in relieving pain?’

PICO can also be used to frame diagnostic questions, but here “I” takes on a new meaning:
P (patient, problem or population)
I (the “issue”): this could be a diagnostic test, a combination of physical tests, or a clinical prediction rule.
C (the comparison): what do you want to compare your diagnostic test to? This could be a reference test or the gold standard test.
O (for outcome): this is usually a measure of the test utility like specificity or sensitivity. This gives you an idea of both the rate of false positives (diagnosing the condition in those that do not have it) and false negatives (missing the diagnosis in those that do).

An example of PICO question about a diagnostic test is: ‘In female soccer players with knee injuries, what is the accuracy of the anterior draw test compared to medical resonance imaging for detecting an anterior cruciate ligament injury?’

Elements of PICO can help you ask questions about the prognosis of a condition. With prognostic questions “I” takes on a new meaning and the “C” is dropped:
P (patient, problem or population): when specifying this element it is useful to include the duration or severity
I (for “time”): over what time span are you interested in, the short- or long-term?
O (for outcome): these should be both quantifiable and important to patient’s goals and priorities. Examples include the rate of disease progression or a positive outcome (eg, return to work or sport).

An example of a PIO question about prognosis is: ‘For people with an episode of back pain resulting in 4 weeks off work, what is the likelihood that they return to work in their previous role at 6 months?’

PEDro has a great video tutorial on posing clinical questions about interventions. This ‘How to ask a clinical question in PICO format’ video is available in English, French, Portuguese, Spanish, Italian, German, Japanese, Tamil, and Chinese simplified characters.