Table 2.

Newcastle–Ottawa Scale (NOS) quality assessment of the included studies

Study	Selection criteria (Max 4 points)	Comparability (Max 2 points)	Outcome (Max 3 points)	NOS quality rating
Leijssen et al.[9]	3	2	2	7/9
Wright et al.[10]	3	1	2	6/9
Orban et al.[11]	4	2	3	9/9
Hammersen et al. [12]	3	2	1	6/9
Hardoy et al.[13]	2	1	1	4/9
Nitschke et al. [14]	3	1	2	6/9
Seidler et al. [15]	4	2	3	9/9
Sygna et al. [16]	3	1	1	5/9
Yamazaki et al. [17]	2	1	1	4/9
Zock et al. [19]	4	2	3	9/9
Yoon et al.[20]	3	1	2	6/9