Table 2.
The quality assessment according to the Newcastle Ottawa Quality Assessment Scale (NOQAS) of each study
| Study | Selection | Comparability | Exposure | Total score |
|---|---|---|---|---|
| Shin [10] | 3 | 3 | 2 | 8 |
| Zhang [11] | 3 | 3 | 2 | 8 |
| Zhao [14] | 3 | 2 | 3 | 8 |
| Cho [16] | 2 | 3 | 3 | 8 |
| Fan [17] | 3 | 2 | 3 | 8 |
| Fan [18] | 3 | 2 | 2 | 7 |
| Fu [19] | 3 | 3 | 2 | 8 |
| Luksameearunothai [20] | 3 | 2 | 3 | 8 |
| Niu [21] | 3 | 3 | 2 | 8 |
| Song [22] | 3 | 2 | 3 | 8 |
| Tan [23] | 3 | 2 | 3 | 8 |
| Wang [24] | 2 | 3 | 2 | 7 |
| Xia [25] | 3 | 2 | 3 | 8 |
| Yu [26] | 3 | 2 | 2 | 7 |
| Zeng [27] | 3 | 3 | 2 | 8 |
| Zuo [28] | 3 | 2 | 3 | 8 |
| Zheng [29] | 3 | 2 | 3 | 8 |
| Khan [30] | 3 | 2 | 2 | 7 |
| Xing [31] | 3 | 3 | 2 | 8 |
| Zhang [32] | 3 | 2 | 3 | 8 |
| Yue [33] | 2 | 3 | 3 | 8 |
| Wei [34] | 3 | 2 | 3 | 8 |
| Zhang [35] | 3 | 2 | 3 | 8 |
| Zhang [36] | 3 | 2 | 3 | 8 |
| Guo [37] | 2 | 3 | 2 | 7 |
| An [38] | 2 | 3 | 2 | 7 |