Table 2.

The Newcastle-Ottawa Scale (NOS) for the Assessment of Case-Control Studies Included in the Meta-Analysis

Selection				Comparability	Exposure			Total Score	Reference
Case defined adequately	Representativeness of the cases	Selection of controls	Definition of controls	Comparability of cases/ controls	Ascertainment of exposure	Same selection method of ascertainment of cases-controls	Same Non response rate in cases/ controls
*	*	*	*	**	*	*	-	8	[43]
*	*	-	*	**	*	*	*	8	[25]
*	*	-	*	**	*	*	-	7	[17]
*	*	-	*	**	*	*	-	7	[26]
*	*	-	*	**	*	*	-	7	[39]
*	*	-	*	**	*	*	-	7	[38]
*	*	-	*	**	*	*	-	7	[36]
*	*	*	*	**	*	*	-	8	[28]
*	*	*	*	**	*	*	-	8	[20]
*	*	*	*	**	*	*	*	8	[27]
*	*	*	*	**	*	*	*	8	[15]
*	*	*	*	**	*	*	-	8	[14]
*	*	-	*	**	*	*	-	7	[37]
*	*	*	*	**	*	*	-	8	[29]
*	*	-	*	**	*	*	-	7	[31]
*	*	-	*	**	*	*	-	7	[30]
*	*	-	*	**	*	*	-	7	[42]
*	*	-	*	**	*	*	-	7	[40]
*	*	*	*	**	*	*	-	8	[33]
*	*	*	*	**	*	*	-	8	[32]
*	*	*	*	-	*	*	-	6	[19]
*	*	*	*	-	*	*	-	6	[18]
*	*	*	*	**	*	*	-	8	[16]