Table 3.

Qualitative risk of bias assessment summary

Study	Sequence generation	Allocation concealment	Blinding of personnel and participants	Blinding of outcomes	Incomplete outcome data addressed	Free of selective reporting	Free of other bias
Askar 2011 [19]	Yes	Yes	Yes	Yes	Unclear	Yes	Yes
Cannizzaro 2014 [12]	Yes	Yes	Yes	Yes	Yes	No	Yes
Di Renzo 2010 [18]	Unclear	Unclear	Yes	Yes	Yes	Unclear	Yes
Docimo 2012 [16]	Unclear	Unclear	Yes	Yes	Yes	Unclear	Yes
Duan 2013 [14]	Unclear	Unclear	Yes	Yes	Unclear	Unclear	Yes
Ferri 2011 [20]	Yes	Unclear	Yes	Yes	Yes	Unclear	Yes
Gentileschi 2011 [21]	Yes	Unclear	Yes	Yes	Unclear	Unclear	Yes
Konturek 2012 [9]	Yes	Yes	Yes	Yes	Yes	Unclear	Yes
Materazzi 2013 [17]	Yes	Yes	Yes	Yes	Yes	Unclear	Yes
Miccoli 2010 [10]	Yes	Yes	Yes	Yes	Unclear	Unclear	Yes
Mourad 2011 [22]	Yes	Yes	Yes	Yes	Yes	Yes	Yes
Pons 2009 [8]	Yes	Unclear	Yes	Yes	Yes	No	Yes
Sista 2012 [13]	Unclear	Unclear	Yes	Yes	Unclear	No	Yes
Soroush 2013 [15]	Unclear	Unclear	Yes	Yes	Unclear	Unclear	Yes

Yes low risk of bias, No high risk of bias