Study | Patient selection | Comparability | Exposure | Total stars |
---|
Belmont 1997 [32] | 4* | 1* | 2* | 7* |
Kuhn 1998 [22] | 3* | 1* | 1* | 5* |
Gong 2002 [33] | 4* | 1* | 1* | 6* |
Xu 2003 [34] | 3* | 1* | 2* | 6* |
Zheng 2006 [35] | 4* | 1* | 1* | 6* |
Bollain 2009 [36] | 4* | 1* | 2* | 7* |
- * indicates item achieves 1piont in Newcastle-Ottawa Scale