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Evidence-Based Medicine: Forming a Question

This guide is designed to point medical students toward literature appropriate for evidence-based medicine.

Identify Your Question/Problem

The EBM process begins when a clinician (You) is presented with a scenario that has some uncertain end or unanswered question. You will find that while many of the cases that you face as a clinician are routine and have a known trajectory, some cases have an air of ambiguity to them. In these situations it is critical that you are able to define the major and defining characteristics of the case and organize them in a uniform and meaningful way. This separating the wheat from the chaff, as it were, is the first step of the EBM process.

This process involves examining your cases and asking several important questions:

  • Who is the subject of this case?
  • What relevant information do I have about my case subject?
  • What is the ultimate desired end in this case?
  • What kind of question is being asked here (harm, diagnosis, prognosis, therapy)? 

These, as well as other, questions will help you key in on the most salient points within your case. With this done you can then move on to the first steps in assessment and elucidate answers to your question.

Searching for Background Questions

What are background questions? These are question that assist the clinician in filling in the gaps that they may have on a given subject.  These are generally reference-based questions that give either quick or definitional knowledge. Examples include:

  • What is the proper pediatric dosage of armodafinil?
  • When is the most prevalent onset of narcolepsy in females?
  • What is Anaphylactic shock?
  • What is the gold standard for treatment of Epistaxis?

Answering these questions will not only give the clinician a fuller view of the case, but also lead them to new understandings and pathways to answering their case question.

Types of Clinical Questions

Clinical questions typically fall into one of four main categories:

Etiology (or harm/risk factors): What causes the problem?

Diagnosis: Does this patient have this problem?

Therapy: What is the best treatment for this problem?

Prognosis: What will the outcome of the problem be?


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

P = Patient/Population or Problem
Describe the patient, population or problem succinctly.  Include the type of patient or population and the setting.  Consider attributes such as age, gender, and/or symptoms.

I = Intervention
The intervention can be a treatment; a clinical, education or administrative intervention; a process of care; nursing treatments; strategies for education; or assessment approaches.

C = Comparison
Determine if a comparison group exists.  Will this intervention be compared to another?  Not all questions have comparisons.  A statement of current practice may be used as a comparison.

O = Outcome
Identify the outcomes of interest.  Outcomes may include quality of life, improved treatment results, decreased rate of adverse events, improved patient safety, decreased cost, or improved patient satisfaction.  The outcomes always include a metric for measuring results and the frequency for measuring and reporting results.

MeSH Database