- Introduction to Evidence-Based Nursing
- Structure of Literature
- Research Design
- Searching the Literature
- Evaluating the Quality of Research
- Tutorial Evaluation
Levels of evidence
Submitted by nursingadmin on Tue, 2006-09-26 16:04
The ability to incorporate Evidence-Based Nursing into clinical care requires a basic understanding of the main research designs underlying the published evidence. Some research designs provide a stronger level of evidence than others based on their inherent characteristics. This hierarchy is often shown graphically as a pyramid:
The pyramid is an appropriate shape for this graphic, as it represents the quality of research designs by level, as well as the quantity of each study design in the body of published literature. Systematic reviews (higher quality), for instance, are the most time-intensive articles to write and are therefore rarer (lower quantity) than other types of studies.
More detailed levels of evidence have been developed by the Oxford Centre for Evidence-Based Medicine. They use a numbering scheme ranging from 1a, homogenous systematic reviews of randomized controlled trials, to 5, expert opinion . This system can be especially useful when comparing articles with similar study designs. Equivalent research designs do not always produce results of equal quality.
Though finding research studies high on the pyramid is preferred, Evidence-Based Nursing may need to draw on research designs lower in the evidence hierarchy than case series. Occasionally nothing but case reports or even bench research may exist on a topic. When making evidence-based decisions for patient care, it is essential to select the highest level research design available for the specific question of interest.
Let's look at the most commonly encountered research designs in Evidence-Based Nursing...Next page >>