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Evidence-Based Practice (EBP)

In addition to the basics of EBP and PICO, this guide answers questions about primary vs. secondary sources, where to look for evidence, and how to search to get the best results.

Which Study Type Best Answers Your Question?

The type of question you need to answer can help you determine what type of study to look for (presented in order of preference):

 ALL CLINICAL QUESTIONS 
  • Systematic review
  • Meta-analysis
  • Clinical practice guideline

TREATMENT (THERAPY)
  • Randomized controlled trial
  • Cohort study
  • Case-control study
  • Case series

ETIOLOGY OR HARM (CAUSATION)
  • Randomized controlled trial
  • Cohort study
  • Case-control study
  • Case series
 DIAGNOSIS
  • Prospective, blind comparison to a gold standard
    (a type of controlled trial)
  • Cohort study
  • Cross-sectional study

PROGNOSIS (NATURAL HISTORY)
  • Cohort study
  • Case-control study
  • Case series

PREVENTION
  • Randomized controlled trial
  • Cohort study
  • Case-control study
  • Case series

See the Study Definitions box below for more about each study type. See the Where and How to Search page for search techniques to find different types of evidence.

Study Definitions & Recommended Databases

Secondary Sources

Studies of studies; titles may contain the word summary, synopsis, or synthesis

  • Practice Guideline (also known as Clinical Practice Guideline or Evidence-Based Guideline): A statement that includes recommendations intended to optimize patient care. Guidelines are informed by a systematic review of evidence and an assessment of the benefits and harms of alternative care options.
  • Systematic Review: A comprehensive summary of high-quality studies examining a given topic
  • Meta-analysis: A type of systematic review in which results from available high-quality studies are statistically combined to compute a net overall effect

Primary Sources

Original studies

  • Randomized Controlled Trial: A carefully planned type of epidemiologic study in which participants are randomly assigned to receive a given exposure (such as a new drug or therapy) and then followed to examine the effects of the exposure on outcomes
  • Cohort Study: A type of epidemiologic study design where one or more population groups (called cohorts) are classified according to their level of exposure to a given agent/risk factor and followed over time to determine if this exposure is related to the occurrence of a disease or outcome of interest
  • Case–Control Study: A type of epidemiologic study that compares individuals who have a disease or outcome of interest (cases) with those who do not (controls). Researchers look retrospectively to evaluate how frequently exposure to a risk factor/agent is present in each group to identify the relationship between the risk factor and the disease or outcome of interest.
  • Cross-Sectional Study: A type of epidemiologic study that observes the relationship between a characteristic/risk factor (the exposure) and the prevalence of the disease or outcome of interest in a specific population at a single point in time
  • Case Series: A summary of a small group of individuals’ experience with a similar disease or outcome of interest
  • Case Reports: A summary of one individual’s experience with the disease or outcome of interest