Table 2 Study-level risk of bias analysis
Study | Bias arising from the randomization process | Bias due to deviations from the intended intervention | Bias due to missing outcome data | Bias in measurement of the outcome | Bias in selection of the reported result | Overall |
|---|---|---|---|---|---|---|
Bai et al. (2020) | Low | Low | Low | Low | Low | Low |
Barwood et al. (2013) | Low | Low | Low | Low | Low | Low |
Chen et al. (2012) | Low | Low | Low | Low | Low | Low |
Fu et al. (2016) | Low | Low | Some concerns | Low | Low | Some concerns |
Haghighi et al. (2017) | Low | Low | Low | Low | Low | Low |
Heiss et al. (2013) | Low | Low | Low | Low | Low | Low |
Heiss et al. (2013) | Low | Low | Low | Some concerns | Low | Some concerns |
Li et al. (2018) | Low | Low | Low | Low | Low | Low |
Ren et al. (2019) | Low | Low | Low | Low | Low | Low |
Rubi-Fessen et al. (2015) | Low | Low | Low | Low | Low | Low |
Seniów et al. (2013) | Low | Low | Low | Some concerns | Low | Some concerns |
Shen et al. (2016) | Low | Low | Low | Low | Low | Some concerns |
Thiel et al. (2013) | Low | Low | Low | Low | Low | Low |
Tsai et al. (2014) | Low | Low | Low | Low | Low | Low |
Waldowski et al. (2012) | Low | Low | Low | Low | Low | Low |
Wang et al. (2014) | Low | Low | Low | Low | Low | Low |
Weiduschat et al. (2011) | Low | Low | Low | Low | Low | Low |
Yoon et al. (2015) | Low | Low | Low | Low | Low | Low |