ADA evidence grading system for clinical practice recommendations*
| Level of evidence | Description |
|---|---|
| *Diabetes Care 2003;26(suppl 1):S1. | |
| †Either all patients died before 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 diabetes ketoacidosis. | |
| A | Clear evidence from well conducted, generalisable, randomised controlled trials that are adequately powered, including: |
| • Multicentre trial | |
| • Meta-analysis incorporating quality ratings | |
| • Compelling non-experimental evidence (i.e. “all or none” rule) developed by the Centre for Evidence Based Medicine at Oxford† | |
| Supportive evidence from well conducted randomised controlled trials that are adequately powered, including: | |
| • Well conducted trials at one or more institutions | |
| B | Supportive evidence from well conducted cohort studies, including: |
| • Prospective cohort studies or registry | |
| • Meta-analysis of cohort studies | |
| Supportive evidence from a well conducted case-control study | |
| C | Supportive evidence from poorly controlled or uncontrolled studies including: |
| • Randomised clinical trials with one or more major or three or more minor methodological flaws that could invalidate the results | |
| • Observational studies with high potential for bias | |
| • Case series or case reports | |
| Conflicting evidence with the weight of evidence supporting the recommendation | |
| E | Expert consensus or clinical experience |