Table 3.

Overview Quality Assessment Questionnaire (OQAQ) for the included systematic reviews.

Reference	(1) Were the search methods reported?	(2) Was the search comprehensive?	(3) Were the inclusion criteria reported?	(4) Was selection bias avoided?	(5) Were the validity criteria reported?	(6) Was validity assessed appropriately?	(7) Were the methods used to combine studies reported?	(8) Were the findings combined appropriately?	(9) Were the conclusions supported by the reported data?	(10) Overall score
Li, 2006 [6]	2	2	2	1	0	0	2	1	2	4
Li, 2006 [7]	1	2	2	1	0	0	2	2	2	3
Huang 2009 [8]	1	1	2	1	0	0	2	2	2	2
Hao et al., 2012 [9]	2	2	2	2	0	0	2	2	2	5
Liu et al., 2012 [10]	2	2	2	1	0	0	2	2	2	4
Li, 2006 [11]	1	2	2	1	0	0	2	2	2	3
Li, 2007 [12]	1	2	2	1	0	0	2	2	2	3
Li, 2006 [13]	1	2	2	1	0	0	2	2	2	3
Li, 2007 [14]	1	2	2	1	0	0	2	2	2	3
Shu, 2010 [15]	2	2	2	2	0	0	2	2	2	5
Li, 2011 [16]	1	2	2	2	0	0	2	2	2	4
Liao, 2012 [17]	2	1	2	2	0	0	2	2	2	4
Li et al., 2012 [18]	2	2	2	2	0	0	2	2	2	5

Note: 2: yes; 1: partly or cannot tell; 0: no.