Table 2 Risk of bias of included studies
| Â | Adequate sequence generation | Allocation concealment | Blinding of participants and personnel | Blinding of outcome assessment | Incomplete outcome data addressed | Free of selective reporting | Free of other bias | Overall |
|---|---|---|---|---|---|---|---|---|
Baker 2006 [18] | Unclear | High Risk | High Risk | Low Risk | Low Risk | Low Risk | Low risk | High risk |
Baker 2015 [32] | Unclear | Unclear | High Risk | Low Risk | High Risk | Low Risk | Low risk | High |
Chen 2013 [29] | Unclear | Unclear | Unclear | Unclear | Low Risk | Unclear | Low risk | Unclear |
Chengappa 2014 [31] | Unclear | Unclear | Low Risk | Low Risk | Unclear | Low risk | Low risk | Unclear |
Dalak 1999 [11] | Unclear | Unclear | Unclear | Unclear | Unclear | High risk | High risk | Unclear |
Evins 2001 [13] | Unclear | Unclear | Unclear | Unclear | Low Risk | Unclear | Low risk | Unclear |
Evins 2005 [17] | Unclear | Unclear | Unclear | Unclear | Unclear | Unclear | High risk | Unclear |
Evins 2007 [19] | Unclear | Unclear | Unclear | Unclear | Unclear | Unclear | Low risk | Unclear |
Fatemi 2013 [30] | Unclear | Unclear | Unclear | Unclear | Unclear | Unclear | Unclear | Unclear |
Gallagher 2007 [20] | Unclear | Unclear | High Risk | High Risk | High risk | Unclear | Low risk | High |
George 2000 [12] | Unclear | Unclear | High Risk | Unclear | Unclear | Unclear | High risk | High |
George 2002 [14] | Unclear | Unclear | Low Risk | Low Risk | Low risk | Unclear | Low risk | Unclear |
George 2008 [21] | Unclear | Unclear | Unclear | Unclear | High risk | High risk | Low risk | High |
Gilbody 2015 [33] | Low Risk | Low Risk | High Risk | High Risk | Low Risk | High Risk | Low risk | High |
Steinberg 2003 [15] | Unclear | Unclear | High Risk | Low Risk | High Risk | Unclear | Low risk | High |
Tidey 2011 [24] | High Risk | High Risk | Low Risk | Low Risk | High Risk | Unclear | High risk | High |
Weinberger 2008 [22] | Unclear | Unclear | Unclear | Unclear | High Risk | Unclear | High risk | High |
Weiner 2011 [25] | Unclear | Unclear | Unclear | Unclear | Unclear | Unclear | Unclear | Unclear |
Weiner 2012 [26] | Unclear | Unclear | Unclear | Unclear | Low risk | Unclear | Low risk | Unclear |
Williams 2010 [23] | Unclear | Unclear | High Risk | Low Risk | High Risk | Unclear | High risk | High |
Williams 2012 [27] | Unclear | Unclear | Low Risk | Low Risk | Low Risk | Low Risk | Unclear | Unclear |
Wing 2012 [28] | Unclear | Unclear | Unclear | Unclear | Unclear | Unclear | Unclear | Unclear |
Wu 2012 [37] | Â | Unclear | Unclear | Unclear | Unclear | Unclear | Unclear | Unclear |
Steinberg 2016 [36] | Unclear | Unclear | High risk | Low risk | Low risk | Unclear | High risk | High |
Smith 2015 [34] | Low risk | Low risk | Low risk | Low risk | Unclear | Unclear | Low risk | Low risk |
Smith 2016 [35] | Low risk | Low risk | Low risk | Low risk | Low risk | Low risk | Unclear | Low risk |