Table 3. Subgroup analysis for the effect of antioxidant vitamin on major cardiovascular events, myocardial infarction, and stroke.

Outcomes	Group	Relative risk (RR)	P value	heterogeneity (%)	P value for heterogeneity
Major cardiovascular events
	Publication year
	Before 2000	0.99 (0.94–1.04)	0.69	0	0.97
	After 2000	1.00 (0.95–1.05)	0.88	14	0.32
	Number of patients
	≥10000	0.99 (0.95–1.03)	0.59	0	0.97
	<10000	1.01 (0.87–1.17)	0.88	48	0.10
	Mean age
	≥60	1.01 (0.93–1.09)	0.89	29	0.23
	<60	0.97 (0.91–1.03)	0.32	0	0.63
	Sex
	Men	0.99 (0.94–1.05)	0.80	0	1.00
	Women	0.94 (0.84–1.06)	0.33	30	0.24
	Both men and women	1.02 (0.96–1.08)	0.58	0	0.42
	History of disease
	Health	0.97 (0.93–1.02)	0.26	0	0.88
	High risk for cardiovascular events	1.02 (0.96–1.08)	0.49	13	0.33
	Duration of follow-up (year)
	≥6	0.99 (0.95–1.03)	0.66	0	0.69
	<6	1.01 (0.92–1.12)	0.83	25	0.26
	Jadad score
	4 or 5	0.99 (0.95–1.04)	0.78	6	0.39
	<4	1.00 (0.93–1.06)	0.89	0	0.64
Myocardial infarction
	Publication year
	Before 2000	0.95 (0.84–1.08)	0.45	61	0.06
	After 2000	1.00 (0.93–1.07)	0.96	6	0.38
	Number of patients
	≥10000	0.98 (0.93–1.04)	0.53	0	0.82
	<10000	0.90 (0.68–1.18)	0.43	61	0.03
	Mean age
	≥60	0.92 (0.77–1.10)	0.35	61	0.03
	<60	1.01 (0.93–1.10)	0.82	0	0.58
	Sex
	Men	0.97 (0.89–1.05)	0.42	0	0.39
	Women	0.97 (0.83–1.12)	0.67	0	0.84
	Both men and women	0.94 (0.77–1.16)	0.59	67	0.02
	History of disease
	Health	0.97 (0.90–1.04)	0.36	0	0.69
	High risk for cardiovascular events	0.98 (0.86–1.11)	0.74	51	0.06
	Duration of follow-up (year)
	≥6	1.00 (0.94–1.06)	0.96	0	0.48
	<6	0.92 (0.76–1.12)	0.42	53	0.06
	Jadad score
	4 or 5	1.00 (0.94–1.06)	0.98	0	0.58
	<4	0.93 (0.75–1.14)	0.47	68	0.02
Stroke
	Publication year
	Before 2000	0.94 (0.83–1.07)	0.37	0	0.57
	After 2000	1.00 (0.93–1.07)	0.99	0	0.81
	Number of patients
	≥10000	0.98 (0.91–1.05)	0.59	0	0.88
	<10000	1.00 (0.88–1.14)	0.96	0	0.49
	Mean age
	≥60	1.02 (0.92–1.13)	0.74	0	0.47
	<60	0.95 (0.82–1.10)	0.50	0	0.81
	Sex
	Men	0.99 (0.89–1.11)	0.89	0	0.47
	Women	0.93 (0.81–1.06)	0.28	0	0.62
	Both men and women	1.04 (0.90–1.20)	0.58	0	0.60
	History of disease
	Health	0.97 (0.89–1.05)	0.45	0	0.57
	High risk for cardiovascular events	1.01 (0.92–1.10)	0.88	0	0.88
	Duration of follow-up (year)
	≥6	0.99 (0.92–1.07)	0.87	0	0.43
	<6	0.97 (0.87–1.08)	0.58	0	0.95
	Jadad score
	4 or 5	0.99 (0.92–1.06)	0.81	0	0.73
	<4	0.96 (0.84–1.11)	0.60	0	0.74