Hierarchy of evidence: a simple system for orthopaedic research?

To be able to make a sound recommendation for a treatment based on the best available evidence, it is necessary to follow specific steps in acquiring literature, appraising the study design and quality, and assessing the results. Evidence-based medicine is founded on the concepts of using best evidence, levels of evidence, and grades of recommendation, and aims to provide clinicians with standardized rules to help them appraise the validity of published research. A number of systems have been developed to categorize research studies into consistent levels of evidence. These systems are based primarily on consensus expert opinion, and have not been validated to any extent. The use of different systems does not allow for effective communication between users; there is a lack of accord even between users of the same system. The GRADE working group has devised a new rating system that attempts to address deficiencies seen within other systems.