Table 1.
Modified from the Oxford Center for Evidence-Based Medicine for Ratings of Individual Studies15
| Quality rating scheme for studies and other evidence | |
|---|---|
| 1 | Properly powered and conducted randomized clinical trial; systematic review with meta-analysis |
| 2 | Well-designed controlled trial without randomization; prospective comparative cohort trial |
| 3 | Case–control studies; retrospective cohort study |
| 4 | Case series with or without intervention; cross-sectional study |
| 5 | Opinion of respected authorities; case reports |