Table 2

Quality assessment of the cross-sectional studies included in systematic review and meta-analysis
Studies Type of study A B C D Total score
Zhang 2006 [14] CS 1 1 1 1 4
Xi 2011 [20] CS 1 1 0 1 3
He 2009 [21] CS 1 1 0 1 3
Huan 2007 [22] CS 1 1 0 1 3
Wu 2008 [23] CS 1 1 0 1 3
Wang 2007 [34] CS 1 1 1 1 4
Bai 2004 [35] CS 1 1 1 1 4
Liao 2009 [36] CS 1 1 0 1 3
Yang 2010 [37] CS 1 1 0 1 3
Zhou 2009 [38] CS 1 1 0 1 3
Li 2002 [39] CS 1 1 0 1 3
Shi 2006 [40] CS 1 1 0 1 3
Yu 2007 [41] CS 1 1 0 1 3
Zhang 2011 [42] CS 1 1 0 1 3
Cai 2007 [43] CS 1 1 0 1 3
Chai 2008 [44] CS 1 1 0 1 3
Tian 2001 [45] CS 1 1 0 1 3
Yang 2011 [46] CS 1 1 1 1 4
Cao 2002 [47] CS 1 1 0 1 3
Geng 2010 [48] CS 1 1 1 1 4
Shi 2008 [49] CS 1 1 1 1 4
Cheng 2005 [50] CS 1 1 1 1 4
Li 2012 [51] CS 1 1 1 1 4
Hou 2001 [54] CS 1 1 0 1 3
Liu 2000 [55] CS 1 1 0 1 3
Li 2010 [56] CS 1 1 0 1 3
Lian 2003 [57] CS 1 1 0 1 3

CC refers to case-control study; CS refers to cross-sectional study. ※ A. representativeness of study participants, B. proper methods to ascertain exposure, C. comparability of comparing analysis groups and D. lower non-response bias.

Li et al.

Li et al. BMC Medicine 2013 11:156   doi:10.1186/1741-7015-11-156

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