Table 2.
Risk of bias assessment according to ROBINS-I.
| Study | Bias due to confounding | Bias in selection of participants | Bias in classification of interventions | Bias due to deviations from intended interventions | Bias due to missing data | Bias in measurement of outcomes | Bias in selection of the reported result | Overall bias |
|---|---|---|---|---|---|---|---|---|
| Aggerholm-Pedersen et al. (2016) | Serious | Low | Low | Low | Moderate | Low | Low | Serious |
| Liu et al. (2016) | Moderate | Low | Low | Low | Serious | Low | Low | Serious |
| Morhij et al. (2017) | Serious | Low | Low | Low | Low | Low | Low | Serious |
| Li YJ et al. (1) (2017) | Low | Low | Low | Low | Low | Low | Moderate | Moderate |
| Li YJ et al. (2) (2017) | Low | Low | Low | Low | Low | Low | Moderate | Moderate |
| Maretty-Kongstad et al. (2017) | Serious | Low | Low | Low | Moderate | Low | Low | Serious |
| Liang et al. (2017) | Low | Low | Low | Low | Low | Low | Moderate | Moderate |
| Tsuda et al.(2017) | Moderate | Low | Low | Low | Moderate | Low | Moderate | Moderate |
| Jiang et al. (2017) | Moderate | Low | Low | Low | Low | Low | Low | Moderate |
| Sasaki et al. (2018) | Serious | Low | Low | Low | Low | Low | Serious | Serious |
| Aggerholm-Pedersen et al. (2019) | Serious | Low | Low | Low | Low | Low | Low | Serious |
| Xu et al. (2019) | Moderate | Low | Low | Low | Low | Low | Low | Moderate |
ROBINS-I is short for Risk Of Bias In Nonrandomized Studies of Interventions, which contains five levels of bias judgment: low, moderate, serious, critical, and no information.