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Research Guides@Tufts

PBL Research Guide

Evidence-Based Medicine

• The conscientious, explicit and judicious use of current best evidence in making decisions about the care of individual patients
• Integrating individual clinical expertise with the best available external clinical evidence from systematic research

DL Sackett, WMC Rosenberg, JAM Gray and WS Richardson, Evidence based medicine: What it is and what it isn't, Br Med J 312 (1996), pp. 71–72.

What's a Foreground Question?

Foreground questions:

  • Ask for specific knowledge to inform clinical decisions for patient care
  • Are formatted using the PICO structure where the foreground question is parsed into specific elements.

For example:

"In smokers with a cough, does a chest x-ray or chest CT have a better positive or negative predictive value for lung cancer?"


Breaking a foreground question in the PICO format helps frame the question, and makes it easier to develop search terms to use in databases such as PubMed to find the best evidence.

If we use the foreground question from the example above, our PICO might look like this:

  • P = Smokers with cough
  • I = Chest x-ray
  • C = Chest CT
  • O = Predicting lung cancer

NOTE! Not all PICOs will have comparisons.

Finding the Best Evidence

Resources at the top of the evidence pyramid:

  • Have the most evidence to support their conclusions.
  • Are the best for answering foreground questions.
  • Are less abundant in the literature.
  • Are the most clinically relevant for decision making.

See the sections below on point-of-care tools and article databases to find answers to foreground questions.

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