Table 2.
Risk of bias of the included studies
| Author | Year | Study type | Selection bias (homogeneity and confounders) | Performance bias (fidelity to protocol) | Attrition bias (loss of participants) | Detection bias (reliable measures) | Reporting bias (selective reporting or conflict interests) | Summary assessment risk of bias |
|---|---|---|---|---|---|---|---|---|
| Alsaadi | 2007 | Retrospective | H | U | U | L | L | L |
| Aguilar-Salvatierra | 2015 | Prospective | H | L | L | L | L | L |
| Anner | 2010 | Retrospective | H | U | U | L | L | M |
| Busenlechner | 2014 | Retrospective | H | L | U | L | L | L |
| Daubert | 2015 | Cross-sectional | H | L | U | L | L | L |
| Dowell | 2007 | Prospective | H | L | L | L | M | M |
| Erdogan | 2014 | Prospective | H | L | L | L | M | M |
| Ferreira | 2006 | Cross-sectional | H | L | L | L | L | L |
| Fiorellini | 2000 | Retrospective | H | M | U | M | L | M |
| Ghiraldini | 2015 | Prospective | H | L | L | L | L | L |
| Gomez-Moreno | 2014 | Prospective | H | L | L | L | L | L |
| Khandelwal | 2011 | Prospective | L | L | L | M | L | L |
| Morris | 2005 | Prospective | H | L | L | M | L | M |
| Moy | 2005 | Retrospective | H | L | U | M | L | M |
| Oates | 2009 | Prospective | H | L | L | L | L | L |
| Oates | 2014 | Prospective | H | L | M | L | L | L |
| Olson | 2000 | Prospective, multicenter | H | L | U | L | L | L |
| Peled | 2003 | Retrospective | H | L | U | M | L | M |
| Tawil | 2008 | Prospective | H | L | L | M | L | M |
| Tatarakis | 2013 | Prospective | H | L | L | L | L | L |
| Turkyilmaz | 2010 | Retrospective | H | L | U | L | L | L |
| Zupnik | 2011 | Retrospective | H | L | U | M | L | M |
L low, M medium, H high, U unknown risk of bias