According to the National Institutes of Health, evidence-based medicine uses the scientific method to organize and apply current data to improve health care decisions. It is a method of integrating clinical expertise, the best research evidence, and patient values and preferences to maximize patient outcomes. The information below provides an overview on how to use evidence-based medicine both in medical training and practice.

There are five steps to evidence-based medicine.

1. ASK: Create a clinical question based on your assessment of the patient

2. ACQUIRE: Find the right resource(s) and conduct the search

3. APPRAISE: Critically appraise the evidence

4. APPLY: Apply the results to patient care

5. ASSESS: Evaluate the outcome

Background questions are those that may be best answered by information found in textbooks or narrative review articles in journals. Example: "What are the complications of gastroesophageal reflux?"

Foreground questions ask for specific knowledge to help make informed clinical decisions and usually concern a specific patient or population. They tend to be more specific and complex compared to background questions. These types of questions often investigate comparisons such as two drugs, two treatments, two diagnostic tests etc...

Example: In patients with primary hypertension, are beta-blockers more effective than other antihypertensive drugs for reducing myocardial infarction mortality?

The acronym PICO is the most common concept used as a bridge between a clinical question and a search strategy, and can be used to build a clinical foreground question. PICO stands for:

Intervention, Prognostic Factor, Exposure
Comparison (optional)

A 62-year-old patient's PSA blood test returned with a Level 4 reading. This falls within the normal range for the patient's age; however, the patient heard on the news that a PSA test misses 82% of tumors in men under the age of 60 and is concerned about the accuracy of the test.

P - Male patients over 60
I - PSA test (or prostate specific antigen)
C - None (the question is not looking at a comparison)
O - Accurate tool for diagnosing prostate cancer

Clinical Question: In male patients over 60 years old (P), is the PSA test (I) an accurate tool for diagnosing prostate cancer (O)?

In addition to PICO, there are other acronyms used to develop clinical questions, depending on the study's purpose. For instance, PICOT adds 'Time' to the equation and PICOTT adds Type of Question and Type of Study.

Point of Care vs. Comprehensive Research Resources

Point of care resources are typically secondary/background filtered resources that are used at the bedside to provide quick overviews of a topic and seminal research. More comprehensive searches typically use databases to retrieve unfiltered content.

Resources for Point of Care include ClinicalKey, DynaMed, PubMed Clinical Queries, Trip, UpToDate and VisualDx.

Resources for Research include Cochrane Library, Embase, MEDLINE, PubMed and Web of Science.

Practice Guidelines

Practice guidelines recommend best clinical practice based on the highest level of available evidence. You can search for them in many of the resources listed above. For information about literature searches and search assistance, visit our Research & Publishing page.

Types of Studies and Levels of Evidence in Hierarchical Order

Meta-Analysis: a statistical analysis that combines results from multiple studies.

Systematic Reviews: exhaustive, well-documented, structured searches in multiple databases with reproducible results.

Randomized Controlled Trial (RCT): study participants are randomly selected to receive, or not receive, an intervention, such as a drug or surgical procedure.

Cohort Studies: longitudinal studies that follow groups of people over time.

Case Control Studies: observational studies that compare different groups of people; one group has a particular disease or condition and the other does not.

Case Reports/Studies/Series: studies an individual or group of individuals of interest.

Question Types Matched to Study Types

Some clinical questions are best answered by certain study types. If the best study type is not available, move to the next level of evidence in the hierarchy.

Therapy: RCT
Diagnosis: Prospective, blind controlled RCT compared to a gold standard
Prognosis: Cohort study
Etiology/Harm: RCT


Review the evidence for validity and applicability to your patient. Tools that guide critical appraisal:

AGREE II (Appraisal of Guidelines for Research and Evaluation II) Reporting Checklist
BMJ Best Practice EBM Toolkit
Centre for Evidence-Based Medicine EBM Tools
JAMAevidence Worksheets (requires personal profile sign-in)

Clinical Calculators

ClinicalKey (select the 'Calculators' link on the ClinicalKey landing page)

Step 4 - APPLY: Relate the Evidence to the Patient
Based on the critical appraisal, apply the best evidence to your patient. Remember to ensure that the evidence and recommendations incorporate patient values and preferences.

Step 5 - ASSESS: Evaluate the Outcome

Reflect on the result of incorporating your clinical expertise, the best evidence, and the patient's values and preferences into improving your patient's outcome. Self-evaluate and determine if further evidence is needed or how you could improve your process in the future.

Learn More about Evidence-Based Medicine and Practice

There are many resources focused on evidence medicine and practice. Here are a few ways to learn more.

Evidence-based medicine: what it is and what it isn't Sackett D.
BMJ 1996; 312(7023) 71-72.

The levels of evidence and their role in evidence-based medicine. Burns PB, Rohrich RJ, Chung KC.
Plast Reconstr Surg 2011; 128(1): 305-310.

Obtaining useful information from expert based sources. Slawson DC, Shaughnessy AF.
BMJ 1997; 314: 947.

The well-built clinical question: a key to evidence-based decisions. Richardson WS, Wilson MC, Nishikawa J, Hayward RS.
ACP J Club 1995 Nov-Dec; 123(3): A12-13.

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