Table 2. Meta-regression analysis.

		95%CI
Heterogeneity sources	Coefficient	Lower	Upper	P
Publication year	0.011	-0.096	0.118	0.839
Population	-0.297	-1.106	0.511	0.471
Method	0.538	-0.702	1.777	0.395
Case sample size	0.078	-0.719	0.874	0.849
Control source	0.982	0.131	1.832	0.024
Control sample	0.450	-0.610	1.510	0.406