Table 3.

Newcastle-Ottawa Scale for case-control studies.

Studies		Solberg et al. (28)	Moss and Adams (29)	Southwell et al. (30)	Schroeder et al. (31)	Stockstill and Callahan (35)	Zach and Andreasen (57)	Curran et al. (36)	Jones et al. (37)	Sirirungrojying et al. (38)	Velly et al. (39)	Manfredini et al. (40)	Pallegama et al. (41)	Saheeb and Otakpor (42)	Vedolin et al. (45)	Giannakopoulos et al. (8)	Lajnert et al. (46)	Schmidt et al. (54)	Reissmann et al. (17)	Staniszewski et al. (56)	Bastos et al. (5)
Selection	Case definition adequate	*	–	–	*	–	*	*	*	*	*	*	*	*	*	*	*	–	*	*	*
	Representativeness of the cases	–	–	–	–	–	*	–	*	–	–	–	–	–	*	–	–	–	*	*	–
	Selection of controls	*	*	*	–	*	*	*	*	*	*	–	*	*	*	*	–	*	–	*	*
	Definition of controls	*	*	–	–	*	*	–	–	–	*	*	*	*	*	*	–	*	–	*	–
Comparability		*	*	*	*	**	*	**	**	*	**	**	**	**	*	*	*	*	*	**	*
Exposure	Ascertainment of exposure	*	–	–	–	–	–	*	–	–	*	*	–	–	*	–	–	–	–	*	–
	Same method of ascertainment for cases and controls	*	*	*	*	*	*	*	*	*	*	*	*	*	*	*	*	*	*	*	*
	Non–Response rate	–	–	–	–	*	*	–	–	–	*	–	–	–	–	*	–	*	*	*	–
Quality		GOOD	POOR	POOR	POOR	FAIR	GOOD	FAIR	FAIR	GOOD	POOR	GOOD	FAIR	FAIR	GOOD	GOOD	POOR	FAIR	POOR	GOOD	POOR

The number of * symbol indicates the number of points assigned to a given parameter.