Table 1 Quality of evidence: number and level of evidence of peer-reviewed and published papers
Hierarchy of evidence | ||
|---|---|---|
Level of evidence | Description | No. of studies |
1 a | Systemic review (with homogeneity*) of randomized, controlled clinical trials (RCTs) | 0 |
1 b | Individual randomized controlled clinical trial (RCT) (with narrow Confidence Interval‡) | 0 |
1 c | All or none case series | 0 |
2 a | Systemic review (with homogeneity*) of cohort studies | 0 |
2 b | Individual cohort study (including low quality RCT; e.g., <80% follow-up) | 0 |
2 c | “Outcomes” Research; Ecological studies | 0 |
3 a | Systemic review (with homogeneity*) of case–control studies | 0 |
3 b | Individual Case–control Study | 23 |
4 | Case-series (and poor quality cohort and case–control studies) | 0 |
5 | Expert opinion without explicit critical appraisal, or based on physiology, bench research or “first principles” | 0 |
Others | Letters to editor, Abstract | 0 |