Table 2 Study bias by Newcastle - Ottawa quality assessment scale
Study | Selection | Comparability | Exposure |
|---|---|---|---|
Kang 2011 [13] | ★★★ | ★ | ★★★★ |
Tsai 2019 [19] | ★★★ | ★ | ★★★★ |
Krane 1999 [20] | ★★★ | ★ | ★★★★ |
Chang 2013 [21] | ★★★ | ★ | ★★★★ |
Weng 2009 [22] | ★★★ | ★ | ★★★★ |
Wu 2014 [23] | ★★★ | ★ | ★★★★ |
Contreras 2014 [24] | ★★★ | ★★ | ★★★★ |
Stock 1993 [31] | ★★★ | ★ | ★★★★ |
Zhu 2009 [32] | ★★★ | ★ | ★★★★ |
Ntatsaki 2018 [16] | ★★ | ★ | ★★★★ |
Zhang 2016 [33] | ★★★ | ★ | ★★★★ |
Levy 2015 [34] | ★★★ | ★ | ★★★★ |
Mustapic 2013 [35] | ★★★ | ★★ | ★★★★ |
Kang 2010 [36] | ★★★ | ★ | ★★★★ |
Oliveira 2012 [37] | ★★ | ★ | ★★★★ |
Lee 2003 [38] | ★★★ | ★ | ★★★★ |