Key Topic 2: Standards of Evidence

You may be aware of the ‘hierarchy of evidence’ shown below. Generally data from systematic reviews and controlled clinical trials are considered to provide stronger evidence than case studies or anecdotal evidence. ‘Real World’ studies are somewhere in between.

The standard of evidence required to support a particular claim will depend on the nature of the claim and the therapy area. In an area that has been well studied, systematic reviews may be easy to find. However in some therapy areas such as very rare conditions the totality of evidence may be from layers lower down in the evidence hierarchy.