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