Table 2.

Quality assessment for the included studies using the Newcastle–Ottawa Scale

The first author (reference)	Selection (out of 4)	Comparability (out of 2)	Exposure/outcome (out of 3)	Total score (out of 9)
Aoki et al. 26	***	–	**	5
Aydin et al. 27	***	–	**	5
Berastegui‐Cabrera et al. 28	****	**	*	7
Buetti et al. 29	***	**	***	8
Buder et al. 30	***	**	**	7
Cho et al. 31	**	–	**	4
Chua et al. 32	**	–	***	5
de la Calle et al. 33	***	**	***	8
He et al. 34	**	**	**	6
Jacot et al. 35	***	–	**	5
Jain et al. 36	****	**	**	8
Kam et al. 37	***	–	**	5
Karahasan Yagci et al. 38	***	**	***	8
Kawasuji et al. 39	**	–	**	4
Kim et al. 40	***	–	**	5
Kociolek et al. 41	****	**	**	8
Kriegova et al. 42	****	–	**	6
Kwon et al. 43	***	**	***	8
Le Borgne et al. 44	****	**	**	8
Piubelli et al. 45	***	**	**	7
Rauch et al. 46	****	**	***	9
Sarkar et al. 47	**	**	**	6
Shlomai et al. 48	**	–	**	4
Shrestha et al. 49	**	**	**	6
Singanayagam et al. 50	****	**	***	9
Soria et al. 51	***	–	***	6
To et al. 52	***	**	**	7
To et al. 53	***	**	**	7
Trunfio et al. 54	***	**	***	8
Tsukagoshi et al. 55	**	–	**
Wang et al. 56	**	–	**	4
Faíco‐Filho et al. 57	****	**	***	9
Guo et al. 58	***	**	***	8
Hasanoglu et al. 59	**	**	**	6