Table 2. Levels and Grade of Evidence for Recommendations280,281
Level
|
Type of Evidence
|
| I |
Evidence is obtained from meta-analysis of multiple, well-designed, controlled studies. Randomized trials have with low false-positive and low false-negative errors (high power). |
| II |
Evidence is obtained from at least one well-designed experimental study. Randomized trials have high false-positive and/or -negative errors (low power). |
| III |
Evidence is obtained from well-designed, quasi-experimental studies such as nonrandomized, controlled, single-group, pre-post, cohort, time, or matched case-control series. |
| IV |
Evidence is from well-designed, nonexperimental studies, such as comparative and correlational descriptive and case studies. |
V
|
Evidence is from case reports and clinical examples.
|
Grade
|
Grade for Recommendation
|
| A |
There is evidence of type I or consistent findings from multiple studies of types II, III, and IV. |
| B |
There is evidence of types II, III, and IV, and findings are generally consistent. |
| C |
There is evidence of types II, III, and IV, but findings are inconsistent. |
| D |
There is little or no systematic empirical evidence. |
|
|
