Table 2.

Quality assessment of studies

Study	Selection	Comparability	Exposure/Outcome	Overall
Kovatcheva et al. (2015) [27]	***	**	***	8
Peek et al. (2016) [28]	***	**	**	7
Kovatcheva et al. (2017) [29]	**	**	***	7
Peek et al. (2017) [30]	***	**	***	8
Hahn et al. (2018) [31]	**	**	***	7
Imankulov et al. (2018) [32]	NA	NA	NA	Moderate
Kwong et al. (2021) [33]	**	**	*	5