Table 2.
Risk of bias in included studies
| Study | Random Sequence Generation | Allocation concealment | Blinding of participants | Blinding of outcome assessment | Incomplete Outcome data | Selective reporting | Other bias |
|---|---|---|---|---|---|---|---|
| Kim 2007 | Yes (Randomization table) | Unclear | Unclear | Yes | Yes | Unclear | Unclear |
| Shen 2007 | Yes (Not reported) | Unclear | Unclear | Unclear | Yes | Unclear | Unclear |
| Karpman 2009 | Yes (Computer) | Unclear | Yes | Yes | Yes | Unclear | Unclear |
| Lin 2009 | Yes (Computer) | Yes (Sealed envelope) | Yes | Yes | Yes | Unclear | Unclear |
| Matsumoto 2011 | Yes (Not reported) | Unclear | Yes | Unclear | Yes | Unclear | Unclear |
| Chiang 2012 | Yes (computer) | Unclear | Yes | Yes | Yes | Yes | Unclear |
| Lin 2013 | Yes (Randomization table) | Yes (Sealed envelope) | Unclear | Yes | Yes | Unclear | Unclear |
| Tasker 2013 | Yes (Randomization table) | Yes (Sealed envelope) | Yes | Yes | Yes | Unclear | Unclear |
| Xu 2013 | Yes (Randomization table) | Yes (Sealed envelope) | Unclear | Unclear | Yes | Unclear | Unclear |
| Roysam 2001 | Yes (Random number table) | Yes (Sealed envelope) | Yes | Yes | Yes | Unclear | Unclear |
| Weinhardt 2004 | Yes (Not reported) | Unclear | Unclear | Unclear | Yes | Unclear | Unclear |
| Bridgman 2009 | Yes (Computer) | Yes (Telephone) | Yes | Yes | Yes | YES | Unclear |
| Sastre 2009 | Yes (Random number table) | Yes (Sealed envelope) | Yes | Yes | No | Unclear | Unclear |
| Pan 2010 | Yes (Computer) | Yes (Sealed envelope) | Yes | No | Yes | Unclear | Unclear |
| Varela-Egocheaga 2010 | Yes (Random number table) | Unclear | Unclear | Unclear | Yes | Unclear | Unclear |
| Van Hemert 2010 | Yes (Not reported) | Unclear | Yes | Yes | Yes | Unclear | Unclear |
| Bourke 2012 | Yes (Computer) | Yes (Sealed envelope) | Yes | Yes | No | Unclear | Unclear |
| Wegrzyn 2013 | Yes (Computer) | Unclear | Yes | Yes | Yes | Unclear | Unclear |
| Jain 2013 | Yes (Computer) | Yes (Block schedule) | Yes | Unclear | Yes | Unclear | Unclear |