De Testimonio: on the evidence for decisions about the use of therapeutic interventions.

Decisions about the use of therapeutic interventions, whether for individuals or entire healthcare systems, should be based on the totality of the available evidence. The notion that evidence can be reliably or usefully placed in 'hierarchies' is illusory. Rather, decision makers need to exercise judgement about whether (and when) evidence gathered from experimental or observational sources is fit for purpose.