Study	Sample size	Proportion (%)	95% CI	Weight (%)	Test for heterogeneity
				Random	Q	200.9922
Goshima et al 2004	318	54.088	48.437 to 59.662	33.28	DF	2
Abou-Zamzam et al 1997	513	12.086	9.393 to 15.224	33.43	Significance level	P < 0.0001
Chung et al 2006	334	41.916	36.567 to 47.410	33.30	I2(inconsistency)	99.00%
Total (random effects)	1165	34.571	10.951 to 63.280	100.00	95% CI for I2	98.37 to 99.39