Table 1.
Basic characteristics of the included studies.
| Author | Year | Country | Study design | PTC/PTMC | Case number obese | Case number normal weight |
| Trésallet C[7] | 2014 | France | retrospective | PTC | 176 | 684 |
| Choi JS[8] | 2014 | Korea | retrospective | PTC | 32 | 451 |
| Choi JS[36] | 2015 | Korea | retrospective | PTMC | 13 | 426 |
| Feng JW[37] | 2019 | China | retrospective | PTC | 25 | 247 |
| Yu ST[38] | 2017 | China | retrospective | PTC | 304 | 826 |
| Kim SH[39] | 2015 | Korea | retrospective | PTC | 33 | 481 |
| Kim SK[40] | 2016 | Korea | retrospective | PTC | 165 | 2740 |
| Wu C[41] | 2017 | China | retrospective | PTC | 64 | 403 |
| Zhao S[42] | 2019 | China | retrospective | PTC | 426 | 1809 |
| Gąsior Perczak D[43] | 2018 | Poland | retrospective | PTC | 398 | 339 |
| Zhu X[44] | 2019 | China | retrospective | PTC | 208 | 1479 |