Table 2.
Included study quality evaluation.
| Study | Quality evaluation (points) | NOS total score | ||
|---|---|---|---|---|
| Selection | Selection of the non-exposed cohort | Exposure or outcome | ||
| Song (2021) | 4 | 2 | 2 | 8 |
| Drennan (2021) | 4 | 1 | 3 | 8 |
| Iliopoulos (2020) | 3 | 2 | 2 | 7 |
| Du (2020) | 4 | 2 | 2 | 8 |
| Xiang (2020) | 4 | 2 | 2 | 8 |
| Mao (2020) | 4 | 2 | 2 | 8 |
| Dai (2020) | 4 | 2 | 3 | 9 |
| Murni (2019) | 4 | 1 | 2 | 7 |
| Perez-Navero (2019) | 4 | 2 | 3 | 9 |
| Sobieraj (2018) | 4 | 1 | 2 | 7 |
| Pérez-Navero (2017) | 4 | 2 | 3 | 9 |
| Wang (2014) | 4 | 1 | 2 | 7 |
| Zhou (2011) | 4 | 2 | 1 | 7 |
| Yang (2009) | 4 | 2 | 3 | 9 |
| Wang (2008) | 3 | 1 | 3 | 7 |
| Song (2008) | 4 | 1 | 3 | 8 |
| Carmona (2008) | 4 | 2 | 3 | 9 |
| Zhu (2007) | 3 | 1 | 2 | 7 |