Nursing 360: EBP & the Evidence Pyramid

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 such as the Evidence Pyramid described below. Systematic reviews, meta-analyses, randomized clinical trials and controlled trials (levels 1-3) are considered to be stronger forms of evidence than levels 4-7.  

EVIDENCE PYRAMID

• Level I:  Systematic review of Randomized Controlled Trials (RCTs) - assessment of evidence by some systematic method, where all the components of the approach and the assessment are made explicit and documented.  Some systematic reviews include meta-analysis. 
  Meta-analysis - A statistical analysis of data from multiple RCTs, in order to help determine the effectiveness of a given health care intervention.
  Evidence-based clinical practice guidelines
• Level II:  Randomized controlled trial - Experimental study in which users are randomly allocated to one of two or more options, where some get the intervention of interest and others get a standard intervention, placebo, or no intervention
• Level III:  Clinical trial or Controlled trial without randomization (quasi-experimental)
• Level IV:  Single nonexperimental study (case-control, correlational, cross-sectional, longitudinal, or cohort studies)
• Level V:  Systematic review of descriptive or qualitative studies 
• Level VI:  Single descriptive or qualitative study
• Level VII: Expert opinion, Reports of expert committees, Quality improvement reports, Evidence-based practice projects ​

Search Tips

For levels 1, 2, and 3 evidence in CINAHL, you may limit your search by Publication Type.  
In PubMed, limit your search by Article Type.

CINAHL Publication Types, Levels 1-3

Clinical Trial
Evidence-Based Care Sheet
Meta Analysis
Nursing Interventions
Practice Guidelines
Protocol
Randomized Controlled Trial
Systematic Review

For Level 4 evidence in CINAHL, clear previous limiters, and copy/paste the following line into the CINAHL advanced search:  
case-control OR correlational OR cross-sectional OR longitudinal OR cohort