Table 1 Characteristics of included studies

Hosseinpanah 2014 [6]

Iran

136 (109/27)

33.6 (18 ~ 45)

2003 Rotterdam criteria

Cross-sectional

^b, d, f

Kim 2014 [7]

Korea

700 (432/268)

27.9 (15 ~ 40)

2003 Rotterdam criteria

Cross-sectional

^a

Lerchbaum 2014 [8]

Austria

706 (352/354)

27^h (16 ~ 45)

2003 Rotterdam criteria

Cross-sectional

^a, b

Livadas 2014 [9]

Greece

1218 (716/502)

23^h

2003 Rotterdam criteria

Cross-sectional

–

Sung 2014 [10]

Korea

1062 (645/417)

24

2003 Rotterdam criteria

Cross-sectional

^{a, c, d, e, f}

Tehrani 2014 [11]

Iran

85 (72/13)

29.07 (18 ~ 45)

2003 Rotterdam criteria

Cross-sectional

^{a, c, d, e, f, g}

Ates 2013 [12]

Turkey

410 (334/76)

24.55

2003 Rotterdam criteria

Cross-sectional

^{a, c, e, f, g}

Di Sarra 2013 [13]

Italy

89 (65/24)

23.6 (18 ~ 40)

2003 Rotterdam criteria

Cross-sectional

^{d, e, f, g}

Zhu 2013 [14]

Shanghai, China

53 (28/25)

22.82

2003 Rotterdam criteria

Cross-sectional

^{d, e, f, g}

Gluszak 2012 [15]

Poland

93 (88/5)

23.95

2003 Rotterdam criteria

Cross-sectional

^{c, d, e, f, g}

Jones 2012 [16]

United Kingdom

29 (19/10)

28

2003 Rotterdam criteria

Cross-sectional

–

Li 2012 [17]

Guangdong, China

131 (62/69)

29.57

2003 Rotterdam criteria

Cross-sectional

^{c, d, e, f, g}

Ozkaya 2012 [18]

Turkey

132 (100/32)

24.21

2003 Rotterdam criteria

Cross-sectional

^{c, d, e, f, g}

Cupisti 2011ⁱ [19]

Germany

309 (293/16)

27.16

2006AES criteriaⁱ

Cross-sectional

^{c, d, e, f, g}

Mehrabian 2011 [20]

Iran

539 (287/252)

29.3 (18 ~ 42)

2003 Rotterdam criteria

Cross-sectional

^{a, b, c, f}

Melo 2011 [21]

Brazil

226 (175/51)

26.45

2003 Rotterdam criteria

Cross-sectional

^{a, c, d, e, f, g}

Wijeyaratne 2011 [22]

Sri Lanka

469 (374/95)

25

2003 Rotterdam criteria

Cross-sectional

^a

Yilmaz 2011 [23]

Turkey

127 (103/24)

25.36 (18 ~ 35)

2003 Rotterdam criteria

Cross-sectional

^{a, c, d, e, f, g}

Castelo-Branco 2010 [24]

Spain

197 (152/45)

28.4

2003 Rotterdam criteria

Cross-sectional

^e, f, g

Guo 2010 [25]

Shandong, China

615 (571/44)

28.3 (20 ~ 41)

2003 Rotterdam criteria

Cross-sectional

^{a, c, d, e, f, g}

Goverde 2009 [26]

Netherlands

157 (101/56)

29 (17 ~ 43)

2003 Rotterdam criteria

Cross-sectional

^{a, b, c, f}

Barber 2007 [27]

United Kingdom

309 (267/42)

33.26

2003 Rotterdam criteria

Cross-sectional

^a

Shroff 2007 [28]

United States

258 (224/34)

27.86 (18 ~ 45)

2003 Rotterdam criteria

Cross-sectional

^{a, c, d, e, f, g}

Chen H 2014 [29]

Shanghai, China

126 (34/92)

27

2003 Rotterdam criteria

Cross-sectional

^{c, d, e, f, g}

Li YC 2014 [30]

Guangxi, China

68 (42/26)

25.51 (18 ~ 37)

2003 Rotterdam criteria

Cross-sectional

^{d, e, f, g}

Ha LX 2013 [31]

Ningxia, China

267 (127/140)

25.21

2003 Rotterdam criteria

Cross-sectional

^{c, d, e, f, g}

Tao T 2013 [32]

Shanghai, China

305 (248/57)

26.44 (18 ~ 45)

2003 Rotterdam criteria

Cross-sectional

^a

Li J 2011 [33]

Shanghai, China

95 (84/11)

Unknown

2003 Rotterdam criteria

Cross-sectional

^{c, d, e, f, g}

Liu L 2011 [34]

Zhejiang, China

48 (34/14)

27.15 (23 ~ 33)

2003 Rotterdam criteria

Cross-sectional

^{d, e, f, g}

Qu ZY 2011 [35]

Shandong, China

306 (177/129)

Unknown

2003 Rotterdam criteria

Cross-sectional

^b

Xu LS 2010 [36]

Tianjin, China

256 (152/104)

23.8 (14 ~ 39)

2003 Rotterdam criteria

Cross-sectional

^b, c

Zhang L 2010 [37]

Jiangsu, China

35 (15/20)

29.43 (21 ~ 35)

2003 Rotterdam criteria

Cross-sectional

^b