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Evidence Based Practice

Learn how to define and search for the common types of high level evidence used in clinical research

How to use an EBP Pyramid

There are a number of different pyramid models showing levels of evidence for EBP. 

The different levels and different names given to types of evidence in these pyramids can be confusing. Some put systems at the top, others start with systematic reviews, or clinical guidelines.  Don’t worry too much about these variations.  If you are lucky enough to find a clinical guideline and a systematic review on your topic – rejoice, because you have found two very high level sources!

The example shown here is the ‘6S’ model (DiCenso, Bayley, & Haines 2009).  It has five ‘filtered’, or ‘pre-appraised’ levels, and one ‘unfiltered’ level. ‘Filtered’ means that the original studies have been critically evaluated to some degree by experts, and therefore the evidence is considered more reliable than the single studies.

To find the best evidence, start at the top and work down, using the explanations and suggested sources to locate articles.


The 6S hierarchy of pre-appraised evidence

6S heirarchy of evidence

DiCenso, A, Bayley, L, Haynes, RB 2009, 'Accessing pre-appraised evidence: fine-tuning the 5S model into a 6S model', Evidence-Based Nursing, vol. 12, pp. 99-101, <https://ebn-bmj-com.ezproxy.utas.edu.au/content/ebnurs/12/4/99.2.full.pdf>.

Systems

Computerised decision support systems designed to link patient characteristics with evidence based guidelines.  These may be integrated into patient health record systems or hospital clinical information systems.

Where to find systems

Only in some specialised healthcare settings, with very limited access.  For study purposes, you should begin with the Summaries level.

Summaries

Regularly updated, broad-based, expert summaries of evidence on clinical topics. Examples are evidence-based texts and clinical guidelines.

Where to find summaries

TRIP = Turning Research Into Practice.  A search engine finding evidence at all levels:  a good starting point. Use the free registration and sign in to access full results.

Topic Overviews provide expert summaries, and links to other resources, such as practice guidelines from professional organisations.

(this link only works on campus, UTAS students may register to access UpToDate off campus)

Operates in a similar way to Dynamed Plus.  The Topic Outline includes expert summaries and links to guidelines.

New NHMRC portal to clinical practice guidelines produced for Australian health care settings.  Content is currently limited, so also try the Clinical Guidelines link below.

Australian and international professional guidelines.

Synopses of syntheses

Descriptions of systematic reviews (syntheses), plus expert appraisal.  These usually appear as articles in evidence based abstraction journals.

Where to find synopses of syntheses

TRIP = Turning Research Into Practice.  A search engine finding evidence at all levels:  a good starting point. Use the free registration and sign in to access full results.


The BMJ produce three EBP journals that systematically search a wide range of international medical journals applying strict criteria for the validity of research and relevance to best practice. Content is critically appraised then the most relevant articles are summarised into a succinct expert commentary focusing on the papers key findings and implications for clinical practice.  These are:

Syntheses

Integrate evidence across several studies on the same topic. Examples of syntheses are systematic reviews and meta-analyses.

Where to find syntheses

TRIP = Turning Research Into Practice.  A search engine finding evidence at all levels:  a good starting point. Use the free registration and sign in to access full results.

Contains systematic reviews (full text), and other evidence levels, which can be selected from the results.

Australian-based evidence, mainly for nursing.

Synopses of studies

Descriptions of a single study, plus expert appraisal of strengths and possible practice changes.  These are usually articles in evidence based abstraction journals.

Where to find synopses of studies

TRIP = Turning Research Into Practice.  A search engine finding evidence at all levels: a good starting point. Use the free registration and sign in to access full results.


The BMJ produce three EBP journals that systematically search a wide range of international medical journals applying strict criteria for the validity of research and relevance to best practice. Content is critically appraised then the most relevant articles are summarised into a succinct expert commentary focusing on the papers key findings and implications for clinical practice.  These are:

Single Studies

Descriptions of what was done in one study, i.e. journal articles reporting on RCTs, Quasi experimental studies, Cohort studies, Case control studies, Case series, Case reports, qualitative studies, etc. Single studies are original research.  They sit at the bottom of the pyramid because they are ‘non-filtered’ – ie they have not been appraised critically for the level or quality of evidence they contain.

Where to find single studies

Look for studies on your topic in the Library's health and medicine databases.  Note:  You will need more complex search techniques for the large databases.  Look up the How To Database Tutorials (link below), or the help/search tips screen in each database, to use them effectively.