Evidence-Based Medicine: Clinical Questions

• Take an identified concern or problem that arises from the care of the patient (the patient's case)
• Construct a question that is relevant to the case and is phrased in such a way as to facilitate finding an answer.
• Define the type of question and the type of study needed to answer that type of question.

• P = Patient, Problem or Population: Characteristics / condition of the patient.
• I = Intervention: What intervention, prognostic factor, or exposure is being considered?
• C = Comparison: What alternative benchmark or gold standard is being considered, if any (examples: placebo, different drug, surgery, no action)?
• O = Outcome: What is the desired accomplishment, improvement, measure?

Image from SlideShare: Evidence Based Medicine Presenter : Dr. Suhasini K. Dept. Community Medicine J.N.M.C., Belagavi 23 January 2015. Slide No. 53 of 79.

More information:

Therapy Question - A question concerning the effectiveness of a treatment or preventative measure

Prognosis Question - A question concerning outcome of a patient with a particular condition

Diagnosis Question - A question concerning the ability of a test to predict the likelihood of a disease

Harm Question - question concerning the likelihood of an intervention to cause harm 

Closer to the top of the pyramid, the study designs are more rigorous and allow for less bias or systematic error. Image courtesy of Duke University Medical Center Library and the Health Sciences Library at the University of North Carolina at Chapel Hill's Introduction to Evidence-based Medicine Tutorial.

These are a few of the publication types associated with evidence-based practice taken from the Glossary of EBM Terms from the Centre for Evidence-Based Medicine Toronto. A more detailed list can be found in the Study Designs document from the National Library of Medicine.

• Meta-analysis: A systematic review that uses quantitative methods to synthesize and summarize results of studies.
• Systematic Review: A summary of the medical literature that uses explicit methods to perform a comprehensive literature search and critical appraisal of individual studies and that uses appropriate statistical techniques fo combine these valid studies.
• Randomized Controlled Trial: A study in which participants are randomly allocated into an experimental group or control group and followed over time for the variables/outcomes of interest.
• Cohort Study: Involves identification of two groups (cohorts) of patients, one which received the exposure and one which did not, and following these cohorts forward for the outcome of interest.
• Case Control Study: A study which involves identifying patients who have the outcome of interest (cases) and patients without the same outcome (controls), and looking back to see if they had the exposure of interest.
• Case Series: A report on a series of patients with an outcome of interest. No control group is involved.