Ranking Evidence according to Evidence-Based Medicine

JH1Whether a new treatment gets marketing approval depends on whether the evidence supporting the effectiveness of this intervention is considered to be justified. The EBM movement developed a series of justifications that are often referred to as ‘hierarchies’ of evidence. My research underpinning the rational (epistemological justification for) these evidence-ranking schemes led to a book on the philosophy of EBM and a revision of the Oxford Centre for Evidence-Based Medicine Levels (OCEBM) of Evidence. The OCEBM Levels is among the most widely used systems for ranking evidence in the world for ranking evidence and thus determining whether treatments are effective. My book has led to the establishment of an interdisciplinary research program where philosophers of medicine, historians of medicine collaborate to help promote good evidence. The research programme includes a series of conferences and a course offered as part of the Oxford Master’s in Evidence-Based Healthcare. The book also provided the justification for the modifications to the OCEBM Levels of Evidence (see below), which had a more direct policy impact.

The Levels are widely used by medical researchers and policy makers (the Levels Table was cited 10 693 times in Google Scholar as of 18 January 2013, and 205 citations in Pubmed as of 18 January 2013). Guideline developers in the UK and around the world use the Levels Table and documents to assess the quality of evidence used to generate recommendations.