Table 2.

Quality assessment result of the observational study using Newcastle–Ottawa scale

	S				C	E/O
References	1	2	3	4	1	1	2	3	SUM
Kapelakis6	–	*	*	*	**	–	*	–	5
Ina19	*	*	–	*	**	*	*	*	8
Baek16	*	*	–	–	–	*	*	*	5
Cao20	*	*	–	–	–	*	*	*	5
Reglat	*	–	*	*	–	*	*	–	5
Căinap	*	*	*	*	–	*	*	–	6
Tsai7	*	*	*	*	**	*	*	–	8
Koca13	*	*	–	–	–	*	*	–	4
Kabbinavar14	*	*	*	*	–	*	*	–	6
Vallerio8	*	–	*	*	–	*	*	–	5
Bencsikova9	*	*	–	–	–	*	*	–	4
Bang15	*	*	*	*	–	*	*	–	6