| Study | Random sequence generation | Allocation concealment | Blinding | Incomplete outcome data | Selective reporting | Other sources of bias |
| KÜPELI 2000 [16] | Unclear | Unclear | Double-blind | Yes | Unclear | Unclear |
| ZENG 2002 [10] | Unclear | Unclear | Double-blind | No | Unclear | Unclear |
| Islam 2012 [11] | Unclear | Unclear | Double-blind | No | Unclear | Unclear |
| WANG Guang 2009 [12] | Unclear | Unclear | Double-blind | No | Unclear | Unclear |
| DING Yan 2010 [17] | Unclear | Unclear | Double-blind | Yes | Unclear | Unclear |
| DONG Xueyi 2006 [18] | Unclear | Unclear | Double-blind | Yes | Unclear | Unclear |
| JIN Yuming 2004 [19] | Unclear | Unclear | Double-blind | Yes | Unclear | Unclear |
| XIE Lei 2006 [20] | Unclear | Unclear | Double-blind | No | Unclear | Unclear |
| Unclear | Unclear | Double-blind | Yes | Unclear | Unclear | |
| ZHANG jing 2009 [22] | Unclear | Unclear | Double-blind | No | Unclear | Unclear |
| ZHANG weixing 2012 [23] | Unclear | Unclear | Double-blind | Yes | Unclear | Unclear |
| LI liyu 2005 [24] | Unclear | Unclear | Double-blind | No | Unclear | Unclear |
| WU yingqiu 2011 [25] | Unclear | Unclear | Double-blind | No | Unclear | Unclear |