Table 1.

The NOS assessment—cross-sectional studies.

	Selection		Comparability			Outcomes
Study	Representativeness of the sample	Sample size	Non-respondents	Ascertainment of the exposure	Confounding factors controlled	Assessment of outcome	Statistical test	Total quality scores
Addington et al.116	0	1	1	2	2	2	1	9
Bentley et al.37	0	1	1	2	2	2	1	9
Boldrini et al.117	1	1	1	2	2	2	1	10
Chudleigh et al.104	0	1	1	2	1	2	1	8
Hodges et al.118	0	1	1	1	1	1	1	6
Huang et al.119	0	1	1	2	2	2	1	9
Loewy et al.120	0	1	1	2	2	2	1	9
Magaud et al.121	0	0	1	2	2	2	1	8
Masillo et al.122	0	1	1	2	0	2	1	7
Masillo et al.123	0	1	1	2	0	2	1	7
Mushtaq et al.124	1	1	1	2	2	2	1	10
Pruessner et al.10	0	1	1	2	2	2	1	9
Shim et al.125	0	1	1	2	0	2	1	7
Vargas et al.126	0	1	1	2	2	2	1	7