Table 3. Quality assessment .
| First author, year | Selection bias | Performance bias | Detection bias | |
|---|---|---|---|---|
| Randomization | Allocation concealment | Blinding of participants and study investigator |
Blinding of outcome assessment |
|
| Choi, 2011 | Unclear | Unclear | Unclear | Unclear |
| Kim, 2010 | Unclear | Unclear | Unclear | Unclear |
| Byeon, 2010 | Unclear | Unclear | Unclear | Unclear |
| Kim, 2009 | Unclear | Unclear | Unclear | Unclear |
| Byeon, 2009 | Unclear | Unclear | Unclear | Unclear |
| Park, 2008 | Low Risk | Unclear | Unclear | Unclear |
| Park, 2004 | Unclear | Unclear | Unclear | Unclear |
| Sung, 2004 | Unclear | Unclear | Unclear | Unclear |
| Kim, 2004 | Unclear | Unclear | Unclear | Unclear |
| Jee, 2003 | Unclear | Unclear | Unclear | Unclear |
| Choi, 2003 | Unclear | Unclear | Unclear | Unclear |
| Cho, 2003 | Unclear | Unclear | Unclear | Unclear |
| Park, 2002 | Unclear | Unclear | Unclear | Unclear |
| Ahn, 2002 | Unclear | Unclear | Unclear | Unclear |
| Kim-1, 1999 | Unclear | Unclear | Unclear | Unclear |
| Kim-2, 1999 | Unclear | Unclear | Unclear | Unclear |
| Jung, 1996 | Unclear | Unclear | Unclear | Unclear |