Nursing 465: EBP & Levels of Evidence

Evidence-based practice (EBP) is "a problem-solving approach to practice that involves the conscientious use of current best evidence in making decisions about patient care."  It involves a systematic search for the most relevant evidence, as well as critical appraisal of the quality (or level) of this evidence to answer a clinical question. 

Sources:  Bennet, C. (2007).  Evidence-based practice. 

Evidence-Based Practice, Step by Step

This series of 12 articles, provided free from the AJN: American Journal of Nursing website, begins with the development of the clinical (PICO) question and carries the reader through the appraisal of evidence, implementation, and dissemination of best practices. 

Research articles in the medical and health sciences can be assigned to a level within a hierarchy. The NURS 360 textbook uses an Evidence Pyramid with seven levels of evidence. The Johns Hopkins model combines levels I - VI and groups them into three categories. Examples, not a complete list, are given below.

• Level I:  
  • Systematic review of randomized controlled trials (RCTs)
  • Meta-analysis of randomized controlled trials
  •  Randomized controlled trial 
• Level II:  Quasi-experimental study or systematic review of a combination of RCTs and quasi-experimental studies 
  • Clinical trials with a control group, but without randomization
• Level III:  Quantitative nonexperimental study or systematic review that includes nonexperimental studies
  • Three categories: Descriptive, correlational, and qualitative univariate 
  • May be retrospective or prospective
  • Examples: case-control, cross-sectional, longitudinal, or cohort studies

Search Tips

In CINAHL, limit your search by Publication Type.
In PubMed, limit your search by Article Type. Here are limiters for Level I studies (listed alphabetically)

• Meta Analysis
• Practice Guideline
• Randomized Controlled Trial
• Systematic Review

For other levels of evidence, clear previous limiters, and use "OR" to string together several keywords that describe the studies you are looking for.  Enter this string on a separate line in your advanced search window.

• For example: clinical trial OR case-control OR correlational OR cross-sectional OR longitudinal OR cohort