Classification used to determine the strength of the recommendations and the quality of the evidence on which the recommendations are based

Category	Definition
A	Good evidence to support a recommendation for use
B	Moderate evidence to support a recommendation for use
C	Insufficient evidence to support a recommendation for or against use
D	Moderate evidence to support a recommendation against use
E	Good evidence to support a recommendation against use
Grade
1	Evidence from at least one properly randomized, controlled trial
2	Evidence from at least one well-designed clinical trial without randomization, from cohort or case-controlled analytic studies, preferably from more than one centre, from multiple time series, or from dramatic results in uncontrolled experiments
3	Evidence from opinions or respected authorities on the basis of clinical experience, descriptive studies or reports of expert committees