Table 2 Assessment of risk of bias in the included studies using Cochrane criteria
Study | Reference | Sequence generation | Allocation concealment | Blinding of participants and personnel | Blinding of outcome assessment | Incomplete outcome data | Selective outcome reporting | Other potential threats to validity |
|---|---|---|---|---|---|---|---|---|
Eshtehardi et al. 2012 | [21] | H | H | H | H | L | L | L |
Guo et al. 2012 | [22] | U | U | H | H | L | L | L |
Hong et al. 2009 | [23] | U | U | H | H | L | L | L |
Hwang et al. 2013 | [24] | H | H | H | L | L | L | H |
Lee et al. 2012 | [14] | L | L | L | L | L | L | L |
Nasu et al. 2009 | [25] | H | H | H | H | L | L | L |
Nozue et al. 2012 | [26] | L | L | H | L | L | L | L |
Puri et al. 2014 | [27] | U | U | H | H | L | L | L |
Taguchi et al. 2013 | [28] | H | H | H | H | L | L | L |