Table 3 Quality assessment using risk of bias assessment tool for non-randomized studies
Study | Selection of participants | Confounding variables | Measurement of exposure | Blinding of outcome assessments | Incomplete outcome data | Selective outcome reporting | Overall risk of bias |
|---|---|---|---|---|---|---|---|
Bali et al. (2016) [33] | unclear | low | low | low | low | low | low |
Chatterjee et al. (2016) [19] | low | low | low | low | low | unclear | low |
Crispo et al. (2016) [34] | unclear | low | low | low | low | low | low |
Hsu et al. (2017) [20] | unclear | low | low | low | low | low | low |
Ishida et al. (2019) [35] | unclear | low | low | low | unclear | low | medium |
Kao et al. (2018) [36] | low | low | low | low | unclear | low | low |
Lu et al. (2015) [37] | unclear | low | low | low | low | low | low |
Machado-Duque et al. (2018) [38] | low | low | low | low | low | high | low |
Moga et al. (2013) [39] | low | low | low | low | low | low | low |
Sørensen et al. (2013) [40] | low | low | low | low | low | low | low |