According to the Centre for Evidence Based Medicine (CEBM), well-formed clinical questions are essential in practicing EBM. "To benefit patients and clinicians, such questions need to be both directly relevant to patients' problems and phrased in ways that direct your search to relevant and precise answers." - CEBM, University of Toronto, Asking Focused Questions
The PICO model is a tool that can help you formulate a good clinical question. Sometimes it's referred to as PICO-T, containing an optional 5th factor.
|P - Patient, Population, or Problem||What are the most important characteristics of the patient? How would you describe a group of patients similar to yours?|
|I - Intervention, Exposure, Prognostic Factor||What main intervention, prognostic factor, or exposure are you considering? What do you want to do for the patient (prescribe a drug, order a test, etc.)?|
|C - Comparison||What is the main alternative to compare with the intervention?|
|O - Outcome||What do you hope to accomplish, measure, improve, or affect?|
|T - Time Factor, Type of Study (optional)||How would you categorize this question? What would be the best study design to answer this question?|
Foreground questions can be further classified into four groups: therapy, diagnosis, prognosis, and etiology/harm. Certain study designs are better suited for answering particular question types.
|Question Type||Definition||Appropriate Study Type(s)|
|Therapy||Questions about the effectiveness of treatment in order to achieve an outcome (drugs, surgical intervention, exercise, counseling, etc.)||Randomized Controlled Trial (RCT)|
|Diagnosis||Questions about identification of a disorder in a patient presenting with specific symptoms||RCT > Cohort Study|
|Prognosis||Questions about the progression of a disease or outcome of a patient with a particular condition||Cohort Study > Case Control Studies > Case Series|
|Etiology/Harm||Questions about the negative impact from an intervention or other procedure||Cohort Study > Case Control Studies > Case Series