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| Author | Year | Country | Study design | RADP n | LDP n | Study quality (score) |
|---|---|---|---|---|---|---|
| Waters[9] | 2010 | USA | Retrospective | 17 | 18 | ****** |
| Kang[10] | 2011 | Korea | Retrospective | 20 | 25 | ****** |
| Daouadi[11] | 2013 | USA | Retrospective | 30 | 94 | ****** |
| Duran[12] | 2014 | Spain | Retrospective | 16 | 18 | ****** |
| Lee[13] | 2014 | USA | Retrospective | 37 | 131 | ****** |
| Chen[14] | 2015 | China | Retrospective | 69 | 50 | ****** |
| Butturini[15] | 2015 | Italy | Prospective | 22 | 21 | ******* |
