Category

Definition

Strength of evidence

A

Evidence bolstering the use of recommendation is strong

B

Evidence bolstering the use of recommendation is fair

C

Evidence is of low quality therefore no support given for or against use

D

Evidence in opposition to use of recommendation is fair

E

Evidence in opposition to use of recommendation is strong

Quality of evidence

I

Evidence from one or more well-designed randomized controlled trial

II

Evidence from one or more well-designed non-randomized clinical trial, from cohort or case controlled analytic studies, or striking results from uncontrolled experiments

III

 Evidence based on judgments of well-regarded authorities, expert clinical experience, or reports of comments by acknowledged authorities.