Table 5.

Scores for assessment of quality for case control studies using the Newcastle Ottawa Scale

	Jory & McGinnis 2008	Rose et al. 2008	Vojdani et al. 2008	James et al. 2009	James et al. 2009 (in vitro)	Al-Gadani et al. 2009	Pasca et al. 2009	Pastural et al. 2009	Geier & Geier 2009	Adams et al. 2009	Mostafa et al. 2010	Vergani et al. 2011	Al-Yafee et al. 2011	Adams et al. 2011	Tirouvanzium et al. 2011	Max score
1 Selection
Case definition	1	1	1	1	2	2	2	1	2	1	2	1	2	1	1	2
Representativeness	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	1
Selection of controls	0	0	1	0	0	0	0	0	0	0	1	0	1	0	0	2
Definition of controls	0	0	0	1	1	0	1	0	0	0	1	1	1	2	1	2
2 Comparability
Control for confounding	0	0	0	1	1	1	2	0	0	0	2	0	0	0	2	2
3 Exposure
Ascertainment	0	0	0	0	0	0	0	0	0	1	0	0	0	1	0	1
Method same for cases/controls	1	1	1	1	1	1	1	1	1	1	1	1	1	1	1	1
Overall score	2	2	3	4	5	4	6	2	3	3	7	3	5	5	5	9