Centre for Evidence Based Medicine

Strength of recommendation A based on a meta-analysis or at least one randomized controlled trial. Strength of recommendation B based on at least one well-designed study, including case control and comparative studies. Strength of recommendation C based on expert reports or opinion (levels of evidence and strength of recommendation. Oxford (UK) Centre for Evidence-Based Medicine. Available at http //www.cebm.net/levels of evidence.asp (accessed December 8,2008). 

For more background, teaching and help on the practice of EBM the database at the Centre for Evidence Based Medicine (CEBM 2008) can be of help. 

CEBM (2008) Centre for Evidence Based Medicine. www.cebm.utoronto.ca/resources/cds.htm be. Cited 30 Dec 2008... 

NHS Centre for Evidence-Based Medicine National Institute for Clinical Excellence (UK) Primary Care Clinical Practice Guidelines Scottish Intercollegiate Guidelines Network (SIGN) The NHS Centre for Reviews and Dissemination TRIP Database UK Cochrane Centre Virtual library... 

Evidence ranking level for etiology depends on the design and quality of studies. The highest level is ranked la and decreases downward. Table modified from the Oxford Centre for Evidence-based Medicine Levels of Evidence website (www.cebm.net/index.aspx o=1025), produced since November 1998 by Bob Phillips, Chris Ball, Dave Sacked, Doug Badenoch, Sharon Straus, Brian Haynes, Martin Dawes. Updated by Jeremy Howick in March 2009. 

Guimer, J., Lee, E. Grapper, M. (2004) Processes and Issues for Improving Access to Medicines The Evidence Base for Domestic Production and Greater Access to Medicines, DFID Health Systems Resource Centre, London. 

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