. 2016 Jan 27;6:17714. doi: 10.1038/srep17714

Table 4. Newcastle-Ottawa Quality Assessment Scale – Case-control studies.

	Is the case definition adequate?	Selection	Selection of Controls	Definition of Controls	Comparability	Ascertainment of exposure	Outcome	Non-response rate	Score
	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 (study adjusts for age, sex)	Ascertainment of exposure	Same method of ascertainment for cases and controls	Non-response rate	Score
Stranges et al. (2008)²⁷	*	*	*	*	**	*	*	*	9
Alessi et al. (2011)²¹	*	*	*	*	**	*	*	*	9
Hernestal-Boman et al. (2012)²²	*	*	*	*	**	*	*	—	8