ADA evidence grading system for clinical practice recommendations
| Level of evidence . | Description . |
|---|---|
| A | Clear evidence from well-conducted, generalizable, randomized controlled trials that are adequately powered including: |
| • Evidence from a well-conducted multicenter trial | |
| • Evidence from a meta-analysis that incorporated quality ratings in the analysis. | |
| • Compelling nonexperimental evidence, i.e., “all or none” rule developed by 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 | |
| B | Supportive evidence from well-conducted cohort studies |
| • Evidence from a well-conducted prospective cohort study or registry | |
| • Evidence from a well-conducted prospective cohort study | |
| • Evidence from a well-conducted meta-analysis of cohort studies | |
| Supportive evidence from well-conducted case-control study | |
| C | Supportive evidence from poorly controlled or uncontrolled studies |
| • Evidence from randomized clinical trials with one or more major or three or more minor methodological flaws that could invalidate the results | |
| • Evidence from observational studies with high potential for bias (such as case series with comparison to historical controls) | |
| • Evidence from case series or case reports | |
| Conflicting evidence with the weight of evidence supporting the recommendation | |
| E | Expert consensus or clinical experience |
| Level of evidence . | Description . |
|---|---|
| A | Clear evidence from well-conducted, generalizable, randomized controlled trials that are adequately powered including: |
| • Evidence from a well-conducted multicenter trial | |
| • Evidence from a meta-analysis that incorporated quality ratings in the analysis. | |
| • Compelling nonexperimental evidence, i.e., “all or none” rule developed by 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 | |
| B | Supportive evidence from well-conducted cohort studies |
| • Evidence from a well-conducted prospective cohort study or registry | |
| • Evidence from a well-conducted prospective cohort study | |
| • Evidence from a well-conducted meta-analysis of cohort studies | |
| Supportive evidence from well-conducted case-control study | |
| C | Supportive evidence from poorly controlled or uncontrolled studies |
| • Evidence from randomized clinical trials with one or more major or three or more minor methodological flaws that could invalidate the results | |
| • Evidence from observational studies with high potential for bias (such as case series with comparison to historical controls) | |
| • Evidence from case series or case reports | |
| Conflicting evidence with the weight of evidence supporting the recommendation | |
| E | Expert consensus or clinical experience |
Either all patients died prior to therapy and at least some survived with therapy, or some patients died without therapy and none died with therapy. Example: use of insulin in the treatment of DKA.