Table 2. Details of study quality evaluation by the Newcastle–Ottawa Scale.
| Study | Representativeness of the exposed cohort | Selection of the non-exposed cohort | Ascertainment of exposure | Outcome not present at baseline | Control for age and gender | Control for other confounding factors | Assessment of outcome | Enough long follow-up duration | Adequacy of follow-up of cohorts | Total |
|---|---|---|---|---|---|---|---|---|---|---|
| van Vlerken 2012 | 0 | 1 | 0 | 1 | 1 | 1 | 1 | 1 | 1 | 7 |
| Bajaj 2012 | 1 | 1 | 0 | 1 | 1 | 1 | 1 | 1 | 1 | 8 |
| de Vos 2013 | 0 | 1 | 1 | 1 | 1 | 1 | 0 | 1 | 1 | 7 |
| Min 2014 | 0 | 1 | 1 | 1 | 1 | 1 | 1 | 0 | 1 | 7 |
| Kwon 2014 | 1 | 1 | 0 | 1 | 1 | 1 | 1 | 1 | 1 | 8 |
| Mandorfer 2014 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 0 | 8 |
| Dultz 2015 | 1 | 1 | 0 | 1 | 1 | 1 | 1 | 1 | 1 | 8 |
| Merli 2015 | 1 | 1 | 1 | 1 | 1 | 1 | 0 | 0 | 1 | 7 |
| Cole 2016 | 0 | 1 | 0 | 1 | 1 | 1 | 1 | 1 | 1 | 7 |
| Kim 2017 | 1 | 0 | 0 | 1 | 1 | 1 | 1 | 1 | 1 | 7 |
| Miozzo 2017 | 0 | 1 | 0 | 1 | 1 | 1 | 1 | 1 | 1 | 7 |
| Hung 2018a | 1 | 0 | 0 | 1 | 1 | 1 | 1 | 1 | 1 | 7 |
| Hung 2018b | 1 | 0 | 0 | 1 | 1 | 1 | 1 | 1 | 1 | 7 |
| Smith 2018 | 0 | 1 | 0 | 1 | 1 | 1 | 1 | 1 | 1 | 7 |
| Tergast 2018 | 1 | 1 | 1 | 1 | 1 | 1 | 0 | 1 | 1 | 8 |
| Janka 2019 | 0 | 1 | 1 | 0 | 1 | 1 | 1 | 1 | 1 | 7 |
| Nardelli 2019 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 9 |
| Lewis 2019 | 0 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 8 |
| Dam 2019 | 1 | 1 | 0 | 1 | 1 | 1 | 1 | 0 | 1 | 7 |
| Hung 2019 | 1 | 0 | 0 | 1 | 1 | 1 | 1 | 1 | 1 | 7 |
| De Roza 2019 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 0 | 1 | 8 |