Study designs of evaluations included in the review
Only randomised controlled trials (RCTs) were eligible for inclusion in the review.
Specific interventions included in the review
Studies that investigated oral vitamin E (tablet or capsule form), alone or with other supplements, compared with a placebo or other control group, were eligible for inclusion. The included studies administered vitamin E at doses ranging from 50 to 600 mg/day, or 400 to 800 IU/day. The comparators in the included studies were beta-carotene, placebo, polyunsaturated fatty acids and aspirin. Vitamin E was combined with beta-carotene, vitamin C, polyunsaturated fatty acids, multiple vitamins and minerals, or aspirin. The duration of the studies ranged from 510 days to 6.1 years.
Participants included in the review
Studies of adult (18 years or older) males or females, with or without risk factors for or existing cardiovascular disease (CVD), were eligible for inclusion. Most of the included studies enrolled patients with existing CVD or at high risk of CVD. About 18% of the participants in the included studies were women.
Outcomes assessed in the review
Studies were included in the review if they assessed one of the primary or secondary outcomes: total myocardial infarction (MI), fatal or nonfatal MI (primary outcomes), total stroke, ischaemic or haemorrhagic stroke, total cardiovascular mortality, or total mortality (secondary outcomes).
How were decisions on the relevance of primary studies made?
Two reviewers assessed studies independently for inclusion. Any disagreements were resolved by consensus, with a third reviewer providing arbitration.