Table 2 Cochrane risk of bias summary of included RCTs
Study | Random Sequence Generation | Allocation Concealment | Blinding of participants and personnel | Blinding of outcome assessment | Incomplete outcome data | Selective outcome reporting | Other sources of bias |
|---|---|---|---|---|---|---|---|
Sandfeldt 2001 [10] | Unclear risk | low risk | low risk | low risk | low risk | low risk | low risk |
HäggstrÖm 2002 [13] | Unclear risk | Unclear risk | high risk | high risk | low risk | low risk | low risk |
Donohue 2002 [8] | Unclear risk | Unclear risk | low risk | Unclear risk | low risk | low risk | low risk |
Liu 2003 [5] | Unclear risk | Unclear risk | high risk | high risk | high risk | low risk | low risk |
Li 2004 [6] | Unclear risk | Unclear risk | high risk | high risk | high risk | low risk | low risk |
Özdal 2005 [4] | Unclear risk | Unclear risk | low risk | Unclear risk | low risk | low risk | low risk |
Lund 2005 [19] | low risk | low risk | Unclear risk | Unclear risk | low risk | low risk | low risk |
Boccon 2005 [16] | Unclear risk | low risk | low risk | low risk | low risk | low risk | low risk |
Lekas 2006 [7] | low risk | Unclear risk | high risk | high risk | low risk | low risk | low risk |
Hahn 2007 [20] | Unclear risk | low risk | low risk | low risk | low risk | low risk | low risk |
Memis 2008 [11] | Unclear risk | Unclear risk | high risk | high risk | low risk | low risk | low risk |
Berardinis 2008 [9] | Unclear risk | low risk | low risk | low risk | low risk | low risk | low risk |
Tuncel 2009 [21] | Unclear risk | Unclear risk | high risk | high risk | high risk | low risk | low risk |
Kravchick 2009 [17] | high risk | low risk | high risk | high risk | high risk | low risk | low risk |
He 2012 | Unclear risk | Unclear risk | high risk | high risk | high risk | low risk | low risk |
Pastore 2013 | low risk | Unclear risk | low risk | Unclear risk | low risk | low risk | low risk |
Liu 2013 [14] | Unclear risk | Unclear risk | high risk | high risk | low risk | low risk | low risk |