Levels of Evidence

Select an evidence rating scale to display detailed information.

Key to interpretation of practice guidelines

Agency for Healthcare Research and Quality:

A: There is good research-based evidence to support the recommendation.
B: There is fair research-based evidence to support the recommendation.
C: The recommendation is based on expert opinion and panel consensus.
X: There is evidence of harm from this intervention.

USPSTF Guide to Clinical Preventive Services:

A: There is good evidence to support the recommendation that the condition be specifically considered in a periodic health examination.
B: There is fair evidence to support the recommendation that the condition be specifically considered in a periodic health examination.
C:There is insufficient evidence to recommend for or against the inclusion of the condition in a periodic health examination, but recommendations may be made on other grounds.
D: There is fair evidence to support the recommendation that the condition be excluded from consideration in a periodic health examination.
E:There is good evidence to support the recommendation that the condition be excluded from consideration in a periodic health examination.

University of Michigan Practice Guideline:

A: Randomized controlled trials.
B: Controlled trials, no randomization.
C: Observational trials.
D: Opinion of the expert panel.

Other guidelines:

A: There is good research-based evidence to support the recommendation.
B: There is fair research-based evidence to support the recommendation.
C: The recommendation is based on expert opinion and panel consensus.
X: There is evidence that the intervention is harmful.