Table 4.
Prevention of the harms from β-carotene by vitamin E (Alpha-Tocopherol Beta-Carotene Study 1985–1993)*
| Subgroup | BC | AT + BC |
|---|---|---|
| Group C: vitamin C ≥90 mg/d and fruit and vegetables ≥275 g/d | ||
| RR | 1·0 | 0·39 |
| 95 % CI | Reference | 0·14, 1·09 |
| Deaths | 13 | 5 |
| Participants | 81 | 73 |
| Person-years | 469 | 443 |
| Rate | 29·1 | 11·6 |
| Group B: vitamin C ≥90 mg/d and fruit and vegetables <275 g/d | ||
| RR | 1·0 | 2·2 |
| 95 % CI | Reference | 0·95, 5·1 |
| Deaths | 8 | 17 |
| Participants | 157 | 157 |
| Person-years | 945 | 915 |
| Rate | 8·3 | 18·4 |
| Group A: vitamin C < 90 mg/d | ||
| RR | 1·0 | 0·72 |
| 95 % CI | Reference | 0·44, 1·2 |
| Deaths | 35 | 30 |
| Participants | 214 | 251 |
| Person-years | 1228 | 1463 |
| Rate | 28·5 | 20·5 |
| Test of difference (2 df) over the subgroups A to C; P | 0·017 | |
BC, β-carotene alone; AT + BC, α-tocopherol and β-carotene combined; RR, risk ratio.
*
This Table shows the head-to-head comparison of the BC and the AT + BC arms shown in Table 3. The BC arm is used as the reference level in this comparison, since the focus is on the effects of vitamin E above BC. Adding a uniform AT + BC effect gave RR 0·87 (95 % CI 0·59, 1·27). Adding an individual AT + BC effect, shown in this Table, to each of the three subgroups improved the fit of the Cox regression model (χ2 (2 df) = 8·1; P = 0·017).