Table 2: Quality of Evidence of Included Studies*.
| Study Design | Level of Evidence |
Number of Eligible Studies |
|---|---|---|
| Large RCT, systematic review of RCTs | 1 | 59 |
| Large RCT unpublished but reported to an international scientific meeting | 1(g) | 0 |
| Small RCT | 2 | 1 |
| Small RCT unpublished but reported to an international scientific meeting | 2(g) | 0 |
| Non-RCT with contemporaneous controls | 3a | 0 |
| Non-RCT with historical controls | 3b | 0 |
| Non-RCT presented at international conference | 3(g) | 0 |
| Surveillance (database or register) | 4a | 0 |
| Case series (multisite) | 4b | 0 |
| Case series (single site) | 4c | 0 |
| Retrospective review, modeling | 4d | 0 |
| Case series presented at international conference | 4(g) | 0 |
†
For each included study, levels of evidence were assigned according to a ranking system based on a hierarchy proposed by Goodman. (45) An additional designation “g” was added for preliminary reports of studies that have been presented at international scientific meetings. Non-RCT, clinical trial that is not randomized, e.g., a cohort study; RCT, randomized controlled trial.
Adapted from the Oxford Centre for Evidence (45)