The original randomized trial, Physicians Health Study I found low dose aspirin regimen decreased the risk of a first myocardial infarction by a very significant 44% helped focus on the role of aspirin in primary prevention of coronary heart disease. This Physicians Health Study is a randomized, double blind, placebo controlled trial designed to determine whether low-dose aspirin (325 mg every other day) decreases cardiovascular mortality and whether beta carotene reduces the incidence of cancer. A slightly increased risk of stroke among those taking aspirin was not statistically significant. Further analyses showed that the reduction in the risk of myocardial infarction was apparent only among those who were 50 years of age and older.
The strong aspirin regimen benefit was present at all levels of cholesterol, but appeared greatest at low levels. The relative risk of ulcer in the aspirin group was 1.22 vs 138 in the placebo group. This trial of aspirin for the primary prevention of cardiovascular disease demonstrates a conclusive reduction in the risk of myocardial infarction but the evidence concerning stroke and total cardiovascular deaths remains inconclusive because of the inadequate numbers of physicians with these study objectives.
Design of Physicians' Health Study II--a randomized trial of beta-carotene, vitamins E and C, and multivitamins, in prevention of cancer, cardiovascular disease, and eye disease, and review of results of completed trials.
To assess the balance of benefits and risks of supplementation with beta-carotene, vitamin E, vitamin C, and multivitamins on cancer, cardiovascular (CVD), and eye diseases.
Physicians' Health Study II (PHS II) is a randomized, double-blind, placebo-controlled trial enrolling 15,000 willing and eligible physicians aged 55 years and older. PHS II will utilize a 2 x 2 x 2 x 2 factorial design to test alternate day beta-carotene, alternate day vitamin E, daily vitamin C, and a daily multivitamin, in the prevention of total and prostate cancer, CVD, and the age-related eye diseases, cataract and macular degeneration.
PRIOR RESULTS: The final results of the recently completed Physicians' Health Study I (PHS I), a randomized, double-blind, placebo-controlled trial in 22,071 healthy US male physicians, indicated that beta-carotene supplementation (50 mg on alternate days) had no significant benefit or harm on cancer or CVD during more than 12 years of treatment and follow-up.
In regards to cancer, there were possible benefits on total and prostate cancer in those with low baseline levels assigned to beta-carotene, a finding compatible with the Chinese Cancer Prevention Study for combined treatment with beta-carotene, vitamin E, and selenium in a poorly nourished population.
Further, with respect to CVD, there were apparent benefits of beta-carotene supplementation on subsequent vascular events among a small subgroup of 333 men with prior angina or revascularization.
The currently available data from randomized trials of primary prevention are sparse and inconsistent for vitamin E and non-existent for vitamin C and multivitamins.
For eye diseases, namely cataract and age-related macular degeneration, there are no completed large-scale randomized trials of antioxidant vitamins.
PHS II is unique in several respects. PHS II is the only primary prevention trial in apparently healthy men testing the balance of benefits and risks of vitamin E on cancer and CVD. In addition, PHS II is the only primary prevention trial in apparently healthy men to test the balance of benefits and risks of vitamin C, multivitamins, as well as any single antioxidant vitamin, alone and in combination, on cancer, CVD, and eye diseases.
Finally, PHS II is the only trial testing a priori the hypotheses that beta-carotene and vitamin E may reduce the risks of prostate cancer.
Thus, PHS II will add unique as well as importantly relevant and complementary information to the totality of evidence from other completed and ongoing large-scale randomized trials on the balance of benefits and risks of beta-carotene, vitamin E, vitamin C, and multivitamins alone and in combination on prevention of cancer, CVD and eye diseases.
Christen WG, Gaziano JM, Hennekens CH. - Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA.