Table 2.

Summary of meta-analysis results and subgroups analysis

Groups	Test of association				Heterogeneity
	OR(95% CI)	P value	Model	Z	Chi square	P value	I square
study design
Cohort	0.72(0.51–1.00)	0.053	Random	1.94	67.04	0.001	95.5%
Case control	0.47(0.18–1.21)	0.116	Random	1.57	68.32	0.001	95.6%
Date of publication
1996–2007	0.71(0.57–0.87)	0.001	Fixed	3.22	5.86	0.119	48.8%
2008–2018	0.48(0.31–0.80)	0.001	Random	3.24	145.62	0.001	97.9%
Sample size
Less than 10,000	0.44(0.18–1.07)	0.075	Random	1.78	65.91	0.001	97.0%
More than 10,000	0.73(0.52–1.03)	0.071	Random	1.81	68.70	0.001	94.2%
Study quality
High	0.71(0.54–0.92)	0.011	Random	2.54	72.00	0.001	93.1%
Moderate	0.31(0.03–3.34)	0.333	Random	0.97	58.49	0.001	98.3%
Overall	0.58(0.42–0.80)	0.001	Random	3.40	152.30	0.001	95.4%