ADA guidelines classification scheme

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Aarti Narayan, M.B.B.S [2]

Overview

The American Diabetes Association (ADA) developed a classification system to grade the quality of scientific evidence to support the ADA recommendations for all position statements. However, ADA encourages physicians to individualize treatment depending on the clinical presentation and characteristics of a particular patient scenario in context.

Levels of Evidence

Level of Evidence A

• Clear evidence from a well-conducted, generalizable, randomized controlled trials that are adequately powered, including:
  • Evidence from a well-conducted multi-center trial.
  • Evidence from a meta-analysis that incorporated quality ratings in the analysis.

• Compelling non-experimental evidence i.e., the 'all or none' rule developed by the Center for Evidence-Based Medicine at Oxford

• Supportive evidence from well-conducted randomized controlled trials that are adequately powered, including:
  • Evidence from a well-conducted trial at one or more institutions.
  • Evidence from a meta-analysis that incorporated quality ratings in the analysis.

Level of Evidence B

• Supportive evidence from well-conducted cohort studies, including:
  • Evidence from a well-conducted prospective cohort study or registry.
  • Evidence from a well-conducted meta-analysis of cohort studies.

• Supportive evidence from well-conducted case-control study.

Level of Evidence C

• Supportive evidence from poorly controlled or uncontrolled studies, including:
  • Evidence from randomized clinical trials with ≥ 1 major or ≥ 3 minor methodological flaws that could invalidate the results.
  • Evidence from observational studies with high potential for bias (such as case seried with comparison to historical controls).
  • Evidence from case series or case reports.

• Conflicting evidence with the weight of evidence supporting the recommendation.

Level of Evidence E

• Expert consensus or clinical experience.