Table 6.
Risk of bias.
| References | Source of bias | |||||
|---|---|---|---|---|---|---|
| Selection bias | Performance bias | Attrition bias | Detection bias | Reporting bias | Overall bias | |
| Sanchez et al. (2008) | + | – | ? | + | – | High |
| Breshears et al. (2011) | + | – | ? | + | – | High |
| Ehlers et al. (2012) | – | – | + | + | – | Medium |
| Pistohl et al. (2012) | + | – | ? | + | – | High |
| Pistohl et al. (2013) | + | – | ? | + | – | High |
| Beveridge et al. (2017) | – | – | ? | + | – | Medium |
| Taherian et al. (2017) | + | + | + | + | + | High |
| Norton et al. (2018) | – | – | – | + | – | Low |
| Jochumsen et al. (2018) | – | – | ? | + | – | Medium |
| Beveridge et al. (2019) | – | – | ? | + | – | Medium |
| Zhang et al. (2019) | – | – | + | – | – | Low |
| Vařeka (2020) | + | – | ? | + | – | High |
+, high-risk of bias; ?, uncertain/non-applicable risk of bias; –, low-risk of bias.