Table 2.
Newcastle-Ottawa Scale for Assessing Quality of Nonrandomized Studies.
| First author | Type of study | Level of evidence | Selection | Comparability | Outcome |
|---|---|---|---|---|---|
| Leven 5 | Retrospective cohort study | 3 | *** | ** | ** |
| Passias 22 | Retrospective cohort study | 3 | *** | ** | ** |
| Yagi 14 | Retrospective cohort study | 3 | **** | ** | *** |
| Yagi 19 | Retrospective cohort study | 3 | *** | ** | *** |
| Yagi 21 | Retrospective cohort study | 3 | **** | ** | *** |
| Yagi 20 | Case-control study | 3 | **** | ** | *** |
| Miller 6 | Retrospective cohort study | 3 | ** | ** | *** |
| Miller 7 | Retrospective cohort study | 3 | **** | * | *** |
| Miller 23 | Retrospective cohort study | 3 | *** | * | *** |
| Passias 1 | Retrospective cohort study | 3 | *** | ** | *** |
| Reid 25 | Retrospective cohort study | 3 | *** | ** | *** |
| Rothrock 24 | Prospective cohort study | 2 | *** | * | ** |
| Scheer 26 | Retrospective cohort study | 3 | *** | * | *** |
| Scheer 27 | Retrospective cohort study | 3 | *** | * | ** |
| Sciubba 28 | Retrospective cohort study | 3 | **** | ** | *** |
| Somani 8 | Retrospective cohort study | 3 | *** | ** | ** |
| Soroceanu 15 | Retrospective cohort study | 3 | **** | ** | *** |
| Soroceanu 31 | Retrospective cohort study | 3 | *** | * | *** |
| Theologis 29 | Retrospective cohort study | 3 | *** | * | *** |
| Whitmore 30 | Prospective cohort study | 2 | *** | ** | ** |
| Zou 32 | Retrospective cohort study | 3 | ** | * | ** |