Table 1.
Characteristics of the selected studies
| Study | Year | Geographical location | Sample size (case/control) | Case
|
Control
|
||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| ε4ε4 | ε4ε3 | ε4ε2 | ε3ε3 | ε3ε2 | ε2ε2 | ε4 | ε3 | ε2 | ε4ε4 | ε4ε3 | ε4ε2 | ε3ε3 | ε3ε2 | ε2ε2 | ε4 | ε3 | ε2 | ||||
| Wang et al21 | 2002 | China (Heifei) | 28/30 | 2 | 9 | 7 | 6 | 3 | 1 | 20 | 24 | 12 | 1 | 4 | 2 | 18 | 4 | 1 | 8 | 44 | 8 |
| Gamarra et al22 | 2015 | Spain | 124/125 | 20 | 66 | 2 | 119 | 9 | 0 | 108 | 313 | 11 | 0 | 49 | 2 | 170 | 22 | 2 | 51 | 411 | 28 |
| Wang et al23 | 2014 | China (Wuzhong) | 216/743 | 1 | 24 | 1 | 135 | 17 | 3 | 27 | 311 | 24 | 6 | 34 | 2 | 580 | 105 | 16 | 48 | 1,299 | 139 |
| Borenstein et al24 | 2010 | China (Shanghai) | 30/32 | 2 | 5 | 2 | 20 | 1 | 0 | 11 | 46 | 3 | 0 | 2 | 1 | 23 | 6 | 0 | 3 | 54 | 7 |
| Wang et al25 | 2014 | China (Beijing) | 56/75 | 0 | 23 | 1 | 26 | 3 | 3 | 24 | 78 | 10 | 0 | 8 | 3 | 51 | 12 | 1 | 11 | 122 | 17 |
| Chen et al26 | 2016 | China (Shanghai) | 583/1,149 | 27 | 129 | 16 | 353 | 56 | 2 | 199 | 891 | 76 | 8 | 156 | 21 | 802 | 154 | 8 | 193 | 1,914 | 191 |
| Chen et al27 | 2016 | China (Ningbo) | 64/54 | 5 | 20 | 0 | 35 | 4 | 0 | 30 | 94 | 4 | 0 | 7 | 0 | 37 | 10 | 0 | 7 | 91 | 10 |
| Hu et al28 | 2005 | China (Guangxi) | 16/96 | 1 | 3 | 1 | 10 | 1 | 0 | 6 | 24 | 2 | 0 | 4 | 1 | 79 | 7 | 5 | 5 | 169 | 18 |
| Xu et al29 | 2009 | China (Guangzhou) | 120/120 | 2 | 36 | 1 | 65 | 16 | 0 | 41 | 182 | 17 | 1 | 16 | 1 | 81 | 21 | 0 | 19 | 199 | 22 |
| Lv and Zhong30 | 2012 | China (Shanghai) | 84/106 | 3 | 20 | 2 | 52 | 6 | 1 | 28 | 130 | 10 | 0 | 15 | 1 | 76 | 12 | 2 | 16 | 179 | 15 |
| He et al31 | 2015 | China (Nanchang) | 120/120 | 4 | 23 | 1 | 79 | 12 | 1 | 32 | 193 | 15 | 0 | 17 | 1 | 83 | 17 | 2 | 18 | 200 | 22 |
| Ye and Zhang32 | 2008 | China (Wuhan) | 56/89 | 2 | 15 | 5 | 31 | 3 | 0 | 24 | 80 | 8 | 1 | 11 | 1 | 64 | 12 | 0 | 14 | 151 | 13 |
| He et al33 | 2015 | China (Shenyang) | 63/60 | 6 | 18 | 1 | 32 | 6 | 0 | 31 | 88 | 7 | 2 | 8 | 1 | 39 | 10 | 0 | 13 | 96 | 11 |
| Yue et al34 | 2013 | China (Nanjing) | 111/90 | 4 | 25 | 3 | 66 | 13 | 0 | 36 | 170 | 16 | 0 | 8 | 0 | 69 | 13 | 0 | 8 | 159 | 13 |
| Chen et al35 | 2011 | China (Guiyang) | 76/152 | 9 | 18 | 28 | 13 | 6 | 2 | 64 | 50 | 38 | 10 | 29 | 38 | 57 | 14 | 4 | 87 | 157 | 60 |
| Kerr et al36 | 2016 | Brazil | 43/144 | 1 | 14 | 1 | 25 | 1 | 1 | 17 | 65 | 4 | 1 | 31 | 2 | 91 | 18 | 1 | 35 | 231 | 22 |
| Lanni et al37 | 2012 | Italy | 70/248 | 2 | 18 | 2 | 41 | 7 | 0 | 24 | 107 | 9 | 0 | 27 | 0 | 201 | 20 | 0 | 27 | 449 | 20 |
| Jairani et al38 | 2016 | India | 87/152 | 4 | 40 | 2 | 35 | 6 | 0 | 50 | 116 | 8 | 20 | 34 | 3 | 82 | 8 | 5 | 81 | 206 | 21 |