Table 4. Quality assessment of observational studies.
| Study | Selection bias | Bias due to residual confounding | Bias due to time-varying covariates/ information censoring | Bias due to selective reporting of study outcomes |
|---|---|---|---|---|
| Alzghari 2018 | Moderate | Moderate | Moderate | Low |
| Chaudhury 2018 | Moderate | Moderate | Moderate | Low |
| Ross 2017 | Moderate | Moderate | Moderate | Low |
| Signorelli 2017 | Moderate | Moderate | Moderate | Low |
| Nicklaus 2018 | Moderate | Moderate | Moderate | Low |
| Phelps 2019 | Moderate | Moderate | Moderate | Low |
| Simmons 2018 | Moderate | Moderate | Moderate | Low |
| Streiff 2018 | Low | Low | Low | Low |
| Zakai 2018 | Low | Low | Low | Low |
| Pritchard 2019 | Moderate | Moderate | Moderate | Low |
Low, low risk; Moderate, moderate risk, unclear risk; High, high risk