Table 4.
Evidence-quality grading based on the GRADE system
| Evidence level | Study design | Study execution | Consistency | Evidence directness |
|---|---|---|---|---|
| A | Pairwise meta-analysis of comparative RCTs (interventions) | No important flaws | Consistent | Direct or strong indirect |
| RCTs (interventions) | ||||
| Non-randomized studies (diagnosis and prognosis) | ||||
|
| ||||
| B | Meta-analysis of RCTs or RCTs (interventions) | Important flaw OR inconsistent OR weak indirect | ||
| Non-randomized studies (diagnosis and prognosis) | ||||
| Non-randomized controlled studies (interventions) | No important flaws | Consistent direct OR strong indirect | ||
|
| ||||
| C | Non-randomized controlled studies (interventions) | Important flaw OR inconsistent OR weak indirect | ||
|
| ||||
| D | Meta-analyses or RCTs with a combination of important flaws AND inconsistency AND/OR indirect evidence Other evidence (not expert opinion) |
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|
| ||||
| E | Expert opinion | |||
Abbreviation: RCTs, randomized controlled trials.