Gradation scale and others levels

Gradation scale

• A

  Established scientific evidence based on studies with a high level of evidence (evidence level 1): high-power randomised controlled trials without major bias, or meta-analyses of randomised controlled trials, decision analyses based on well-conducted studies.

• B

  Scientific presumption based on a scientific presumption provided by studies with an intermediate level of evidence (evidence level 2), such as low-power, randomised controlled trials, well-conducted non-randomised controlled studies or cohort studies.

• C

  Low level of evidence based on studies with low levels of evidence, such as case-control studies (evidence level 3), retrospective studies, case series, comparative studies with significant biases (evidence level 4).

• AE

  Expert agreement: where no studies exist, recommendations are based on agreement between work group experts, after consultation with the reading group. A recommendation which has not been graded may nevertheless remain relevant and useful. The absence of grading should, however, encourage authors to conduct complementary studies.

Other levels

• Expert commentary
  Comments from several experts in the pathology in question, solicited by the work group on recommendations.
  These experts do not participate in the work group meetings.

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