Table 5. Test(s) of heterogeneity .

	Heterogeneity statistic	Degrees of freedom	P -value	I-squared**	Tau-squared
myocardial infarction	81.56	8	0.001	90.2%	0.957
Coronary Heart Disease	61.15	16	0.001	73.8%	0.271
cardiac syndrome X	2.50	3	0.475	0.0%	0.000
Overall	201.68	29	0.001	85.6%	0.610
**I-squared: the variation in OR attributable to heterogeneity), Note: between group heterogeneity not calculated; only valid with inverse variance method Significance test(s) of OR=1
Myocardial infarction	z= 2.74		p = 0.006
Coronary Heart Disease	z= 3.48		p = 0.000
cardiac syndrome X	z= 8.29		p = 0.000
Overall	z= 5.32		p = 0.000