Table 1 Outcomes of risk of bias assessment of all included studies
Study | Mackay et al. 2002 [19] | Andersen et al. 2015 [34] | Kang et al. 2015 [35] | Bjerrum et al. 2016 [36] | GĂĽldner et al. 2017 [37] | Gallagher et al. 2012 [38] | Verdaasdonk et al. 2006 [39] |
|---|---|---|---|---|---|---|---|
Random sequence generation (selection bias) | Low risk | High risk | High risk | Low risk | Low risk | Low risk | Low risk |
Allocation concealment (selection bias) | Low risk | High risk | High risk | Low risk | Low risk | Low risk | Low risk |
Blinding of participants and personnel (performance bias) | Low risk | Low risk | Low risk | Low risk | Low risk | Low risk | Low risk |
Blinding of outcome assessment (detection bias) | Unclear risk | Low risk | Low risk | Low risk | Low risk | Low risk | Low risk |
Incomplete outcome data (attrition bias) | Low risk | High risk | Low risk | Low risk | Low risk | Low risk | Low risk |
Selective reporting (reporting bias) | Low risk | Unclear risk | Low risk | Low risk | Low risk | Low risk | Low risk |
Other bias | Low risk | Low risk | Low risk | Unclear risk | Low risk | Low risk | Low risk |