Table 2—

Levels of evidence

Level of evidence AData derived from multiple randomised clinical trials# or meta-analyses.
Level of evidence BData derived from a single randomised clinical trial# or large nonrandomised studies.
Level of evidence CConsensus of opinion of the experts and/or small studies, retrospective studies, registries.
  • #: or large accuracy or outcome trial(s) in the case of diagnostic tests or strategies.