Table 2. Meta-regression analysis.

Heterogeneity sources	Coef.(95%CI)	t	p	τ2	I2 Res(%)	R2(%) Adjusted
Control type	−0.36(−0.65,0.063)	−2.4	0.018	0.37	63.77	17.67
Ethnicity	0.35(−0.31,1.02)	1.07	0.29	0.45	67.72	1.06
Sample size	−0.0036(−0.011,0.004)	−0.96	0.34	0.48	68.83	−5.23
Method	−0.12(−0.61,0.38)	−0.47	0.64	0.48	68.84	−6.17