Table 3.

Results of cumulative meta-analysis of studies in chronological order.

Study	No. of studies (cases/samples)	Heterogeneity		Model	Meta-analysis
		I2(%)	p		HR	95% CI	p
Michaud et al., 2008	1(543/48375)	NA	NA	NA	1.17	0.96-1.43	0.12
Arora et al., 2010	2(717/79041)	0	0.92	Fixed-effect	1.17	0.97-1.41	0.11
Wen et al., 2014	3(905/232607)	0	0.43	Fixed-effect	1.09	0.93-1.27	0.29
Nwizu et al., 2017	4(1104/298476)	0	0.64	Fixed-effect	1.09	0.95-1.25	0.22

CI, confidence interval; HR, hazard ratio; NA, not available.