Table 3.
Efficacy of vitamin and antioxidant supplements in prevention of major cardiovascular events in subgroup meta-analysis by outcome
| No of trials | Relative risk (95% CI) | Heterogeneity I2 (%) | Model | |
|---|---|---|---|---|
| Cardiovascular death | 32 | 1.01 (0.97 to 1.05) | 41 | Fixed effects |
| Vitamin A | 2 | 0.98 (0.45 to 2.16) | 87 | Random effects |
| Vitamin B6 | 8 | 0.91 (0.83 to 0.99)* | 0 | Fixed effects |
| Low quality trials | 4 | 0.93 (0.75 to 1.14) | 12 | Fixed effects |
| High quality trials | 4 | 0.90 (0.82 to 0.99)* | 0 | Fixed effects |
| Not supplied by pharmaceutical industry | 2 | 0.96 (0.84 to 1.10) | 0 | Fixed effects |
| Supplied by pharmaceutical industry | 2 | 0.85 (0.75 to 0.97)* | 0 | Fixed effects |
| Not supplied by pharmaceutical industry | 3 | 0.96 (0.83 to 1.10) | 0 | Fixed effects |
| Supplied by pharmaceutical industry | 5 | 0.88 (0.79 to 0.98)* | 0 | Fixed effects |
| Vitamin B12 | 9 | 0.96 (0.90 to 1.03) | 27 | Fixed effects |
| Folic acid | 11 | 0.96 (0.89 to 1.03) | 11 | Fixed effects |
| Vitamin C† | 6 | 1.03 (0.95 to 1.12) | 27 | Fixed effects |
| Vitamin D | 3 | 0.90 (0.76 to 1.07) | 27 | Fixed effects |
| Vitamin E† | 15 | 0.98 (0.92 to 1.04) | 37 | Fixed effects |
| β carotene | 10 | 1.10 (0.96 to 1.27) | 61 | Random effects |
| Selenium | 15 | 0.98 (0.92 to 1.04) | 37 | Fixed effects |
| Vitamin | 2 | 0.98 (0.45 to 2.16) | 87 | Random effects |
| Angina | 10 | 1.04 (1.00 to 1.08)* | 36 | Fixed effects |
| Low quality trials | 6 | 1.05 (1.00 to 1.09)* | 25 | Fixed effects |
| High quality trials | 4 | 1.01 (0.86 to 1.18) | 57 | Random effects |
| Vitamin B6 | 4 | 0.93 (0.72 to 1.20) | 77 | Random effects |
| Vitamin B12 | 4 | 0.93 (0.72 to 1.20) | 77 | Random effects |
| Folic acid | 4 | 0.93 (0.72 to 1.20) | 77 | Random effects |
| Vitamin C† | 2 | 0.94 (0.85 to 1.03) | 0 | Fixed effects |
| Vitamin D | 1 | 1.07 (0.93 to 1.23) | NA | NA |
| Vitamin E† | 3 | 1.15 (0.99 to 1.33) | 0 | Fixed effects |
| Myocardial infarction | 34 | 1.00 (0.96 to 1.03) | 0 | Fixed effects |
| Vitamin B6 | 13 | 0.99 (0.91 to 1.07) | 11 | Fixed effects |
| Vitamin B12 | 14 | 0.99 (0.93 to 1.06) | 4 | Fixed effects |
| Folic acid | 15 | 0.99 (0.93 to 1.06) | 0 | Fixed effects |
| Vitamin C† | 4 | 0.96 (0.87 to 1.07) | 0 | Fixed effects |
| Vitamin D | 2 | 1.06 (0.92 to 1.21) | 0 | Fixed effects |
| Vitamin E† | 12 | 0.77 (0.65 to 0.91)* | 76 | Random effects |
| Low quality trials | 5 | 0.76 (0.57 to 1.01) | 81 | Random effects |
| High quality trials | 7 | 0.75 (0.58 to 0.97)* | 75 | Random effects |
| Not supplied by pharmaceutical industry | 4 | 0.79 (0.53 to 1.17) | 62 | Random effects |
| Supplied by pharmaceutical industry | 3 | 0.67 (0.42 to 1.07)* | 86 | Random effects |
| Primary prevention | 7 | 0.72 (0.54 to 0.95)* | 76 | Random effects |
| Not supplied by pharmaceutical industry | 3 | 0.79 (0.42 to 1.50) | 55 | Random effects |
| Supplied by pharmaceutical industry | 4 | 0.63 (0.42 to 0.97)* | 82 | Random effects |
| Secondary prevention | 5 | 0.79 (0.61 to 1.02) | 80 | Random effects |
| Not supplied by pharmaceutical industry | 4 | 0.79 (0.53 to 1.17) | 62 | Random effects |
| Supplied by pharmaceutical industry | 8 | 0.73 (0.59 to 0.92)* | 82 | Random effects |
| β carotene | 4 | 0.95 (0.80 to 1.14) | 52 | Random effects |
| Selenium | 3 | 0.87 (0.59 to 1.28) | 0 | Fixed effects |
| Fatal myocardial infarction | 9 | 1.02 (0.92 to 1.12) | 43 | Fixed effects |
| Vitamin B6 | 1 | 1.00 (0.75 to 1.33) | NA | NA |
| Vitamin B12 | 1 | 1.00 (0.75 to 1.33) | NA | NA |
| Folic acid | 1 | 1.00 (0.75 to 1.33) | NA | NA |
| Vitamin E† | 3 | 0.57 (0.32 to 1.03) | 0 | Fixed effects |
| β carotene | 1 | 1.05 (0.95 to 1.17) | NA | NA |
| Selenium | 1 | 1.12 (0.43 to 2.87) | NA | NA |
| Non-fatal myocardial infarction | 13 | 0.83 (0.66 to 1.04) | 89 | Random effects |
| Vitamin B6 | 3 | 1.08 (0.90 to 1.30) | 22 | Fixed effects |
| Vitamin B12 | 4 | 1.03 (0.93 to 1.14) | 1 | Fixed effects |
| Folic acid | 4 | 1.03 (0.93 to 1.14) | 1 | Fixed effects |
| Vitamin C† | 4 | 0.85 (0.70 to 1.04) | 0 | Random effects |
| Vitamin E† | 9 | 0.57 (0.32 to 1.03) | 0 | Fixed effects |
| β carotene | 4 | 0.95 (0.80 to 1.14) | 52 | Random effects |
| Selenium | 3 | 0.82 (0.53 to 1.27) | 0 | Fixed effects |
| Stroke | 32 | 0.97 (0.93 to 1.02) | 0 | Fixed effects |
| Vitamin B6 | 12 | 0.93 (0.85 to 1.01) | 13 | Fixed effects |
| Vitamin B12 | 5 | 0.91 (0.80 to 1.03) | 8 | Fixed effects |
| Folic acid | 7 | 0.90 (0.79 to 1.01) | 19 | Fixed effects |
| Vitamin C† | 4 | 0.98 (0.88 to 1.09) | 0 | Fixed effects |
| Vitamin D | 5 | 1.00 (0.88 to 1.13) | 6 | Fixed effects |
| Vitamin E† | 12 | 1.00 (0.93 to 1.09) | 20 | Fixed effects |
| β carotene | 2 | 0.98 (0.89 to 1.07) | 0 | Fixed effects |
| Selenium | 1 | 1.09 (0.68 to 1.72) | NA | NA |
| Transient ischaemic attack | 5 | 1.12 (0.97 to 1.30) | 0 | Fixed effects |
| Vitamin B6 | 2 | 1.12 (0.88 to 1.42) | 0 | Fixed effects |
| Vitamin B12 | 2 | 1.12 (0.88 to 1.42) | 0 | Fixed effects |
| Folic acid | 2 | 1.12 (0.88 to 1.42) | 0 | Fixed effects |
| Vitamin D | 1 | 1.12 (0.96 to 1.42) | NA | NA |
| Vitamin E† | 2 | 0.93 (0.59 to 1.47) | 0 | Fixed effects |
NA=not applicable.
*P≤0.05.
†For subgroup meta-analysis of vitamin C and vitamin E, we used data from 2008 PHS2 article83 because data were not available in 2012 PHS article.