Table 2.

Quality assessment of included studies based on Newcastle–Ottawa Scale

References	Country	Selection	Comparability	Outcome	Total
Abisi et al. [8]	UK	***	**	**	7
Evans et al. [15]	UK	***	**	**	7
Hurks et al. [16]	Netherlands	****	**	***	9
Karrowni et al. [2]	US	***	*	**	6
Mosorin et al. [5]	Finland	***	**	**	7
O’Donell et al. [17]	US	****	**	***	9
Raux et al. [18]	France	****	*	**	7
Stein et al. [19]	US	**	**	*	5
Sukhija et al. [20]	US	***	*	**	6
Wilson et al. [21]	UK	**	**	*	5