Table 2. . Newcastle Ottawa Scale quality assessment of the included studies.

Study	Selection				Comparability	Outcomes
	Representativeness of the exposed cohort	Selection of the nonexposed cohort	Ascertainment of exposure	The outcome was not present at the start of the study	Comparable cohort	Assessment of outcome	Follow-up long enough	Adequacy of follow-up of the cohort
Hernández-Fernández et al.(2020)	*	*	*	*	*	*	*	*
Li et al. (2020)	*	*	*	*	*	*	*	*
Lodigiani et al. (2020)	*	*	*	*	*	*	*	*
Zhang et al. (2020)	*	*	*	*	*	*	*	*
Annie et al. (2020)	*	*	*	–	–	*	*	*
Fan et al. (2020)	*	*	*	–	*	*	*	*
Shahjouei et al. (2020)	*	*	*	–	*	*	*	*
Bach et al. (2020)	*	*	*	–	*	*	*	*