Table 2.
Description of scientific levels of evidence and corresponding studies 5.
| Level of Evidence | Description |
|---|---|
| Level 1 | Randomized controlled trials with adequate follow-up Meta analysis of multiple randomized control trials |
| Level 2 | Non-randomized, controlled prospective trial Prospective cohort studies |
| Level 3 | Well designed observational studies (e.g. comparative studies, correlation study, case control study) |
| Level 4 | Retrospective observational studies without controls Case-series |
| Level 5 | Expert opinions or committee recommendations |