Table 2 Risk of bias and literature quality
Trials | Random sequence generation | Allocation concealment | Blinding | Incomplete outcome data treatment | Selective outcome reporting | Other bias | Jadad score |
|---|---|---|---|---|---|---|---|
High Quality | Â | Â | Â | Â | Â | Â | Â |
Van der Linden, 2005 [23] | Low | Unclear | High | Low | Low | Low | 4 |
Mahmood, 2007 [24] | Low | Low | High | Low | Low | Low | 5 |
Godet, 2008 [25] | Low | Low | High | Low | Low | High | 4 |
Mukhtar, 2009 [26] | Unclear | Low | Unclear | Low | Low | Unclear | 4 |
Schramko, 2009 [28] | Unclear | Low | Unclear | Low | Low | Low | 4 |
Gondos, 2010 [38] | Unclear | Low | Unclear | Low | Low | Low | 4 |
Schramko, 2010 [30] | Unclear | Low | High | Low | Low | Low | 4 |
Du, 2011 [41] | Low | Unclear | Unclear | High | High | Low | 4 |
James, 2011 [42] | Low | Low | Low | High | Low | Low | 6 |
Myburgh, 2012 [6] | Low | Low | Low | Low | Low | Low | 7 |
Alavi, 2012 [33] | Unclear | Low | Low | Low | Low | Low | 4 |
Nagpal, 2012 [34] | Low | Low | Low | Unclear | Low | Low | 5 |
Kimenai, 2013 [35] | Low | Unclear | High | Low | Low | Low | 4 |
Low Quality | Â | Â | Â | Â | Â | Â | Â |
Ley, 1990 [22] | Unclear | Unclear | Unclear | Low | Low | Unclear | 2 |
Berard, 1994 [36] | Unclear | Unclear | Unclear | Low | Low | Low | 2 |
Chen, 2006 [37] | Low | Unclear | High | Low | Low | Unclear | 3 |
Ooi, 2009 [27] | Unclear | Unclear | High | Low | Unclear | Low | 2 |
Choi, 2010 [29] | Low | Unclear | Unclear | Low | Low | Low | 3 |
Heradstveit, 2010 [39] | Unclear | Unclear | High | Low | Low | High | 2 |
Inal, 2010 [40] | Unclear | Unclear | Unclear | Low | Unclear | Low | 2 |
Lee, 2011 [31] | Unclear | Unclear | High | Low | Low | Low | 2 |
Yang, 2011 [32] | Low | Unclear | Unclear | High | Low | Low | 3 |