Table 2.

Qualitative assessment of the studies by the Newcastle-Ottawa Quality Assessment scale for Cohort and Case-Control Studies (NOS).

		Selection				Comparability	Exposure			Total
	Diagnosis	Is the case definition adequate?	Representativeness of the cases	Selection of controls	Definition of controls	Comparability of cases and controls on the basis of the design or analysis	Ascertainment of exposure	Same method of ascertainment for cases and controls	Non-response rate	Number of stars
Prehn-Kristensen (32)	ADHD			*			*			2
Jiang (33)	ADHD			*	*		*		*	4
Zhai (39)	ASD				*	*	*			3
Liu (38)	ASD	*			*	*	*			4
Pulikkan (36)	ASD			*	*		*			3
Zhang (37)	ASD		*	*	*		*		*	5
Luna (35)	ASD	*			*	*	*			4
Son (34)	ASD		*	*			*			3
Hicks (40)	ASD				*		*			2
Qiao (41)	ASD	*	*	*		*	*			5