Table 2.

MINORS appraisal scores for the included retrospective studies

Study	Methodologic itemsa												Total
	1	2	3	4	5	6	7	8	9	10	11	12
Yang et al. 2006 [11]	2	0	0	2	0	2	2	0	2	2	2	2	16
Janssen et al. 2007 [13]	2	1	0	2	0	2	2	0	2	2	2	2	17
Zhang 2007 [16]	2	1	0	2	0	2	2	0	2	2	2	1	16
Vallier et al. 2008 [9]	2	2	0	2	0	2	2	0	2	2	2	2	18
Chen et al. 2008 [17]	2	1	0	2	0	2	2	0	2	2	2	2	17
Huang 2008 [18]	2	1	0	2	0	2	2	0	2	2	2	2	17
Ni 2010 [19]	2	1	0	2	0	2	2	0	2	2	2	2	17
Feng 2011 [32]	2	1	0	2	0	2	2	0	2	2	2	2	17
Wu 2011 [20]	2	1	0	2	0	2	2	0	2	2	2	1	16
Huang 2012 [21]	2	1	0	2	0	2	2	0	2	2	2	2	17
Jin 2012 [22]	2	0	0	2	0	2	2	0	2	2	2	2	16
Li 2012 [14]	2	1	0	2	0	2	2	0	2	2	2	2	17
Ren 2012 [23]	2	1	0	2	0	2	2	0	2	2	2	1	16
Seyhan et al. 2012 [12]	2	0	0	2	0	2	2	0	2	2	2	2	16
Tan 2012 [24]	2	1	0	2	0	2	2	0	2	2	2	2	17
Yang 2012 [25]	2	1	0	2	0	2	2	0	2	2	2	2	17
Ke 20113 [26]	2	1	0	2	0	2	2	0	2	2	2	2	17
Wang 2013 [27]	2	0	0	2	0	2	2	0	2	2	2	2	16
Yao 2013 [28]	2	1	0	2	0	2	2	0	2	2	2	2	17
Zhu 2013 [29]	2	1	0	2	0	2	2	0	2	2	2	2	17
Dong 2014 [30]	2	1	0	2	0	2	2	0	2	2	2	2	17
Guo 2014 [31]	2	1	0	2	0	2	2	0	2	2	2	2	17
Yavuz 2014 [15]	2	1	0	2	0	2	2	0	2	2	2	2	17

^aMethodologic items: (1) a clearly stated aim; (2) inclusion of consecutive patients; (3) prospective collection of data; (4) endpoints appropriate to the aim of the study; (5) unbiased assessment of the study endpoint; (6) follow-up period appropriate to the aim of the study; (7) loss to follow up, which is less than 5 %; (8) prospective calculation of the study size; (9) an adequate control group; (10) contemporary groups; (11) baseline equivalence of groups; and (12) adequate statistical analyses. The items are scored as “0” (not reported), “1” (reported but inadequate), or “2” (reported and adequate). The global ideal score for comparative studies is 24 [41]