Enormous efforts have been made to establish evidence based medicine, to protect patients from ineffective or harmful treatments and unjustified claims while ensuring that appropriate treatments are offered. A simplistic view presupposes that after treatments are rigorously evaluated, results are incorporated into clinical guidelines within best practice criteria, which, in turn, inform policies. However, the process that leads to effective sustainable solutions to health problems is in fact non-linear, with different forms of evidence needed at different stages by different parties.

Even the concept of scientific evidence is fairly new. Randomised controlled trials only came to the fore after the discovery of antibiotics in the 1940s.1 For some people, the rightful dominance of such trials in evidence hierarchies2 has meant that they form the only acceptable evidence of treatment efficacy and safety in health research. Although it is agreed that treatments based on anecdotal evidence should be rejected, some vital evidence from non-randomised controlled trials has previously been devalued or dismissed. Such research suffers from lack of funding and a lower priority for publication.3 4

Diseases such as cancer, diabetes, and heart disease are seldom cured but may be modified, even prevented, …