Evidence Based Practice
Levels of Evidence
Medical scientists and practitioners rank evidence according to its quality. When these types of evidence are ranked as levels, one on top of the other, the resulting image takes the form of a pyramid. This is because the higher the quality of evidence, the rarer it is, and the lower the quality of evidence, the more ubiquitous it is. The highest quality evidence (level 1 evidence) is the systematic review:
Levels of Evidence (Video, Duration: 8min.) University of Louisville, 2018.
EBP Process
The first stage of any evidence-based practice process is formulating an answerable question. This forms the foundation for quality searching. A well-formulated question will facilitate the search for evidence and will assist you in determining whether the evidence is relevant to your question.
There are a number of frameworks available and the one you use will depend on your discipline area and the focus of your question. Examples include PICO, ECLIPSE, SPIDER and SPICE.
See the “Framing your research question” guide for more information on frameworks.
CQUniversity Library pays for subscription licenses to scholarly publications. Your hospital library in the clinical setting may also provide full-text access to some of these resources.
You can locate CQUniversity’s Evidence-Based Practice databases under the Type of Resource, Evidence-Based Practice section of the library Databases page.
Critical appraisal uses intrinsic (research design, not extrinsic (author, journal, institution)) factors. You'll need to consider the following when appraising an article:
- Quality
- Did the literature you found include randomised and double-blind trials to avoid selection bias and observer bias?
- Did the original trials keep track of most of their subjects right through to the end of the trial?
- Validity
- Did the trials you found mimic clinical practice?
- Could they be used in clinical practice?
- Do the outcomes of the trials make sense?
- Reliability
- Are the trials you found reported in the literature credible and repeatable?
- Were these trials run with large enough cohorts to provide reliable data?
- Relevance
- How does the evidence from this article inform my research?
- How does it inform my practice?
These videos will provide an introduction to the concept of critical appraisal.
Introduction to Critical Appraisal (Video, Duration 9min.)
Developed by Cochrane Common Mental Disorders in collaboration with York University, Northumberland, Tyne and Wear NHS Foundation Trust (NTW), UK and Tees, Esk and Wear Valleys NHS Foundation Trust (TEWV), UK.
Systematic reviews and meta-analysis (Video, Duration: 29min.)
Developed by Cochrane Common Mental Disorders in collaboration with York University, Northumberland, Tyne and Wear NHS Foundation Trust (NTW), UK and Tees, Esk and Wear Valleys NHS Foundation Trust (TEWV), UK.
Resources for EBP
You can use this worksheet to help you with your PICO and search strategy for your assignment question.
- A worked example has been provided for your assistance.
See Framing your question for more information about question frameworks like PICO and it's variants.
There are a number of checklists / tools available on the Internet to assist you in undertaking critical appraisal of evidence. Some examples are listed below.
- Appraisal Tools - Critical Appraisal Skills Programme (UK)
- EBM Practice Guidelines: Appraisal Guide (Canada) This handbook focuses on how to evaluate and use the evidence gathered from a systematic literature review to inform the development of evidence-based clinical guidelines.
- A systematic review of the content of critical appraisal tools (article) This article summarizes the content, intent, construction, and psychometric properties of published, currently available critical appraisal tools to identify common elements and their relevance to allied health research.
- Systematic Reviews & Other Review Types - Tools for Critical Appraisal
- Systematic Reviews & Other Review Types - What is a Systematic Review?
There are several valuable resources available on the Internet. Many are from government departments, educational institutions, or not-for-profit organisations. Below are a couple of examples of the resources available.
Note: Before using any websites, you need to evaluate the content and reliability of each site carefully.
- CareSearch - information and resources about palliative care
- McMaster Health Forum - Find Evidence This is a repository of syntheses of research evidence about governance, financial and delivery arrangements within health systems, and about implementation strategies that can support change in health systems. The types of syntheses include evidence briefs for policy, overviews of systematic reviews, systematic reviews, systematic reviews in progress (i.e. protocols for systematic reviews), and systematic reviews being planned (i.e. registered titles for systematic reviews).
You can improve your chances of finding relevant information by limiting your search results. To do this you can use the advanced search option and limit to education, government, or organisation domains. The following search strategies could be used in Google:
- educational institutions in the United Kingdom:
"evidence-based practice" site.ac.uk - organisations
"evidence-based practice" site:.org - organisations in Australia
"evidence based practice" site:.org.au
