Table 3.
Risk of bias assessment*
| Sun (2011)[24] | Zheng (2010)[25] | He (2010)[36] | Wei (2010)[37] | Ni (2010)[26] | Tang (2010)[38] | Luo (2009)[27] | Zhou (2008)[28] | He (2006)[29] | Zhao (2005)[30] | Wang (2005)[39] | Li (2002)[31] | Ge (2000)[32] | Yu (1999)[33] | Yu (1999)[34] | Yu (1996)[35] | Ruan (1995)[40] | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 1. Was the method of randomization adequate? |
Y |
U |
Y |
U |
U |
U |
U |
U |
U |
U |
U |
Y |
U |
U |
U |
U |
U |
| 2. Was the treatment allocation concealed? |
Y |
U |
U |
U |
U |
N |
N |
U |
U |
N |
U |
U |
U |
U |
U |
U |
U |
| 3. Was the patient blinded to the intervention? |
N |
N |
N |
N |
N |
N |
N |
N |
N |
N |
N |
N |
N |
N |
N |
N |
N |
| 4. Was the outcome assessor blinded to the intervention? |
U |
U |
N |
U |
U |
U |
N |
U |
U |
N |
U |
U |
U |
U |
U |
U |
U |
| 5. Were incomplete outcome data adequately addressed? |
N |
Y |
Y |
Y |
Y |
Y |
Y |
Y |
Y |
Y |
Y |
Y |
Y |
Y |
Y |
Y |
Y |
| 6. Are reports of the study free of suggestion of selective outcome reporting? | N | N | Y | N | N | N | Y | Y | N | Y | Y | Y | Y | Y | Y | Y | Y |
*, Based on the risk of bias assessment tool from the Cochrane Handbook for Systematic Reviews of Interventions [16]; ‘Y’ indicates “Yes (low risk of bias)”; ‘U’, “Unclear”; ‘N’, “No (high risk of bias)”; A study with a low risk of bias was defined as a study receiving ‘Y’ for randomization and/or allocation concealment.