A prospective study of cigarette smoking and risk of age-related macular degeneration in men

OBJECTIVE

To examine the association between cigarette smoking and the incidence of age-related macular degeneration (AMD) in men.

DESIGN

Prospective cohort study with average person-years of follow-up for AMD of 12.2 years.

PARTICIPANTS

A total of 21 157 US male physicians participating in the Physicians' Health Study who did not have a diagnosis of AMD at baseline, were followed for at least 7 years, and had known levels of baseline smoking. Based on information reported at baseline, 11% were current smokers, 39% were past smokers, and 50% were never smokers.

MAIN OUTCOME MEASURE

Incident AMD, defined as a self-report that was confirmed by medical record, review, first diagnosed after randomization, and responsible for vision loss to 20/30 or worse.

RESULTS

A total of 268 incident cases of AMD with vision loss were confirmed. In multivariate analysis, current smokers of 20 or more cigarettes per day, compared with never smokers, had an increased risk of AMD (relative risk [RR], 2.46; 95% confidence interval [CI], 1.60-3.79). Past smokers had a modest elevation in risk of AMD (RR, 1.30; 95% CI, 0.99-1.70). For current smokers of fewer than 20 cigarettes per day, there was a nonsignificant 26% increased risk of AMD (RR, 1.26; 95% CI, 0.61-2.59).

CONCLUSIONS

These prospective data provide support for the hypothesis that cigarette smoking increases the risk of developing AMD.

Lack of effect of long-term supplementation with beta carotene on the incidence of malignant neoplasms and cardiovascular disease

BACKGROUND

Observational studies suggest that people who consume more fruits and vegetables containing beta carotene have somewhat lower risks of cancer and cardiovascular disease, and earlier basic research suggested plausible mechanisms. Because large randomized trials of long duration were necessary to test this hypothesis directly, we conducted a trial of beta carotene supplementation.

METHODS

In a randomized, double-blind, placebo-controlled trial of beta carotene (50 mg on alternate days), we enrolled 22,071 male physicians, 40 to 84 years of age, in the United States; 11 percent were current smokers and 39 percent were former smokers at the beginning of the study in 1982. By December 31, 1995, the scheduled end of the study, fewer than 1 percent had been lost to follow-up, and compliance was 78 percent in the group that received beta carotene.

RESULTS

Among 11,036 physicians randomly assigned to receive beta carotene and 11,035 assigned to receive placebo, there were virtually no early or late differences in the overall incidence of malignant neoplasms or cardiovascular disease, or in overall mortality. In the beta carotene group, 1273 men had any malignant neoplasm (except nonmelanoma skin cancer), as compared with 1293 in the placebo group (relative risk, 0.98; 95 percent confidence interval, 0.91 to 1.06). There were also no significant differences in the number of cases of lung cancer (82 in the beta carotene group vs. 88 in the placebo group); the number of deaths from cancer (386 vs. 380), deaths from any cause (979 vs. 968), or deaths from cardiovascular disease (338 vs. 313); the number of men with myocardial infarction (468 vs. 489); the number with stroke (367 vs. 382); or the number with any one of the previous three end points (967 vs. 972). Among current and former smokers, there were also no significant early or late differences in any of these end points.

CONCLUSIONS

In this trial among healthy men, 12 years of supplementation with beta carotene produced neither benefit nor harm in terms of the incidence of malignant neoplasms, cardiovascular disease, or death from all causes.

Homocysteine metabolism and risk of myocardial infarction: relation with vitamins B6, B12, and folate

Elevated plasma homocyst(e)ine levels are an independent risk factor for vascular disease. In a case-control study, the authors studied the associations of fasting plasma homocyst(e)ine and vitamins, which are important cofactors in homocysteine metabolism, with the risk of myocardial infarction. The cases were 130 Boston area patients hospitalized with a first myocardial infarction and 118 population controls, less than 76 years of age, enrolled in 1982 and 1983. Dietary intakes of vitamins B6, B12, and folate were estimated from a food frequency questionnaire. After adjusting for sex and age, the authors found that the geometric mean plasma homocyst(e)ine level was 11% higher in cases compared with controls (p = 0.006). There was no clear excess of cases with extremely elevated levels. The age- and sex-adjusted odds ratio for each 3-mumol/liter (approximately 1 standard deviation) increase in plasma homocyst(e)ine was 1.35 (95% confidence interval 1.05-1.75; p trend = 0/007). After further control for several risk factors, the odds ratio was not affected, but the confidence interval was wider and the p value for trend was less significant. Dietary and plasma levels of vitamin B6 and folate were lower in cases than in controls, and these vitamins were inversely associated with the risk of myocardial infarction, independently of other potential risk factors. Vitamin B12 showed no clear association with myocardial infarction, although methylmalonic acid levels were significantly higher in cases. Comparing the mean levels of several homocysteine metabolites among cases and controls, the authors found that impairment of remethylation of homocyst(e)ine (dependent of folate and vitamin B12 rather than on vitamin B6-dependent transsulfuration) was the predominant cause of high homocyst(e)ine levels in cases. Accordingly, plasma folate and, to a lesser extent, plasma vitamin B12, but not vitamin B6, correlated inversely with plasma homocyst(e)ine, even for concentrations at the high end of normal values. These data provide further evidence that plasma homocyst(e)ine is an independent risk factor for myocardial infarction. In this population, folate was the most important determinant of plasma homocyst(e)ine, even in subjects with apparently adequate nutritional status of this vitamin.

Anti-platelet effects of 100 mg alternate day oral aspirin: a randomized, double-blind, placebo-controlled trial of regular and enteric coated formulations in men and women

AIM

While regular use of low-dose aspirin has been recommended for several groups of patients at risk of vascular occlusion, the optimal dose of aspirin to produce a cardiovascular benefit whilst minimizing side effects is uncertain. Further, while enteric coated preparations may reduce gastrointestinal symptoms, the antiplatelet effects of these formulations have not been completely tested. In addition, exceptionally few data relating to these issues have been available in women.

METHODS

To determine whether a 100 mg alternate day dose of aspirin given in regular and enteric coated formulations for a 2-week period is sufficient to inhibit platelet function in men and women, a randomized, double-blind, placebo-controlled trial was conducted among 22 healthy volunteers evaluating the effects of these preparations on platelet aggregation induced by arachidonic acid, adenosine diphosphate, and epinephrine, and on plasma concentrations of thromboxane and prostacyclin.

RESULTS

During the active aspirin phase of the study, all subjects demonstrated a clinical anti-platelet effect as evidenced by failure of the platelets to aggregate in the presence of at least one platelet agonist, and mean thromboxane and prostacyclin levels decreased to 7.5 and 15.6% of baseline, respectively (both P < 0.001). After cessation of active aspirin, all subjects had fully recovery of platelet function as well as thromboxane and prostacyclin production. There were virtually no differences between regular and enteric coated formulations, or between men and women.

CONCLUSION

These data indicate that an alternate day regimen of 100 mg aspirin given in either regular or enteric coated formulation is adequate to achieve functional platelet inhibition. The clinical efficacy of this dose and formulation of aspirin is being tested in the ongoing Women's Health Study, a randomized, double-blind, placebo-controlled trial of 40000 female health professionals designed in part to assess the benefits and risks of 100 mg alternate day aspirin in the primary prevention of cardiovascular disease.

Self-reported breast implants and connective-tissue diseases in female health professionals. A retrospective cohort study

OBJECTIVE

To evaluate the association of breast implants with connective-tissue diseases.

DESIGN AND PARTICIPANTS

Retrospective cohort study of 395,543 female health professionals who completed mailed questionnaires for potential participation in the Women's Health Study. A total of 10,830 women reported breast implants and 11,805 reported connective-tissue diseases between 1962 and 1991. Cox proportional hazards regression models were used in analyses.

MAIN OUTCOME MEASURE

Self-reported connective-tissue diseases.

RESULTS

Compared with women who did not report breast implants, the relative risk (RR) of the combined end point of any connective-tissue disease among those who reported breast implants was 1.24 (95% confidence interval, 1.08 to 1.41, P = .0015). With respect to the individual diseases, the finding for other connective-tissue diseases (including mixed) was statistically significant (P = .017), the findings for rheumatoid arthritis, Sjogren's syndrome, dermatomyositis or polymyositis, or scleroderma were of borderline statistical significance (.05 < P < .10), and the finding for systemic lupus erythematosus was not statistically significant (P = .44). There were no clear trends in RR with increasing duration of breast implants.

CONCLUSION

These self-reported data from female health professionals are compatible with prior reports from other cohort studies that exclude a large hazard, but do suggest small increased risks of connective-tissue diseases among women with breast implants. The very large sample size makes chance an unlikely explanation for the results, but bias due to differential overreporting of connective-tissue diseases or selective participation by affected women with breast implants remains a plausible alternative explanation. The major contribution of this and other observational analytic studies has been to exclude large risks of connective-tissue diseases following breast implants.

Ways of measuring rates of recurrent events

Recurrent events are common in medical research, yet the best ways to measure their occurrence remain controversial. Moreover, the correct statistical techniques to compare the occurrence of such events across populations or treatment groups are not widely known. In both observational studies and randomised clinical trials one natural and intuitive measure of occurrence is the event rate, defined as the number of events (possibly including multiple events per person) divided by the total person-years of experience. This is often a more relevant and clinically interpretable measure of disease burden in a population than considering only the first event that occurs. Appropriate statistical tests to compare such event rates among treatment groups or populations require the recognition that some individuals may be especially likely to experience recurrent events. Straightforward approaches are available to account for this tendency in crude and stratified analyses. Recently developed regression models can appropriately examine the association of several variables with rates of recurrent events.

Interobserver agreement in the classification of stroke in the physicians' health study

BACKGROUND AND PURPOSE

The evaluation of cerebrovascular end points in prospective studies is often based exclusively on medical record examination and may be made by more than one observer over time. To address the issues of adequacy of medical record information and consistency in diagnosis over time, we evaluated interobserver agreement for the main items of the stroke classification system used in the Physicians' Health Study. This trial included 22,071 physicians randomly assigned in 1982 to receive either aspirin or placebo to assess the subsequent risk of cardiovascular events, including stroke.

METHODS

Stroke subtype, stroke severity, and certainty of diagnosis were first classified from medical records from the years 1982 through 1988. The 216 stroke events reported in this period were independently reclassified in 1994 and compared with the initial classification using kappa statistics.

RESULTS

Overall agreement in major stroke types (hemorrhagic, ischemic, undetermined stroke) as well as in hemorrhagic stroke subtypes was excellent (kappa = 0.81 and kappa = 0.95, respectively). A wide range of values for the ischemic stroke subtypes (kappa = 0.13 to kappa = 0.96) was obtained. Agreement was substantial in assessment of stroke severity (kappa = 0.71), and it was fair (kappa = 0.33) for certainty of diagnosis.

CONCLUSIONS

Interobserver agreement is high for major stroke types as well as for categories of hemorrhagic stroke on the basis of review of medical records and results of imaging data. The classification of ischemic stroke subtypes, however, is subject to substantial interobserver disagreement. Periodic reclassification of random samples of end points might be considered in long-term prospective studies to assess potential misclassification of events by different observers.

Antioxidant vitamin-cardiovascular disease hypothesis is still promising, but still unproven: the need for randomized trials

The hypothesis that antioxidant vitamins might decrease the risk of cardiovascular disease (CVD) is a promising area of research. At present, however, it is far from certain whether antioxidant vitamins confer protection against CVD. Evidence for the antioxidant vitamin-cardiovascular disease hypothesis has accumulated from several lines of research. Laboratory research has identified biochemical properties of antioxidant vitamins that could explain their possible role in inhibiting and delaying coronary atherosclerosis. Epidemiologic studies have provided support for the hypothesis by showing that people who consume high amounts of antioxidant vitamins through diet or supplements, or those with high concentrations of these nutrients in their blood, tend to have lower risks of CVD. In the case of the former, however, laboratory findings may not have relevance to free-living humans. Observational epidemiologic studies cannot exclude the possibility that people who consume antioxidant-rich diets or who take vitamin supplements also share other lifestyle or dietary practices that actually account for their lower disease rates. Because of these uncertainties, the only way to determine reliably whether antioxidants play any role in reducing the risk of CVD is to conduct large-scale, randomized trials of these agents, in which adequate doses of antioxidant vitamins are tested for a sufficient duration to allow for any benefits to emerge. Several large-scale trials are now ongoing in both primary and secondary prevention. The results of these trials over the next several years should provide reliable evidence for this promising, but as yet unproven, hypothesis.

Physical exercise and reduced risk of nonfatal myocardial infarction

While the inverse association between physical activity and coronary heart disease risk is well documented, questions remain regarding the intensity of exercise, the potential for confounding by other risk factors for coronary heart disease, and the role of blood lipids and apolipoproteins. The authors examined these issues in the Boston Area Health Study, a case-control study of 340 patients (266 men, 74 women) who survived a first myocardial infarction between January 1, 1982, and December 31, 1983, and 340 controls matched on sex, age, and residence. The relative risk of myocardial infarction for those in the highest quartile of physical activity, compared with the lowest, was 0.50 (95 percent confidence interval (CI) 0.31-0.80) for men and 1.00 (95 percent CI 0.41-2.43) for women. When subjects were categorized by level of energy expenditure on moderate to vigorous sports alone, men in the most active category had 0.39 (95 percent CI 0.23-0.69) times the risk of those in the least active category, and women, 0.43 (95 percent CI 0.15-1.26) times the risk. Adjustment for body mass index, smoking, alcohol intake, diet, personal and family medical history, and personality type did not substantially change results nor did further adjustment for blood lipids. This was not surprising as total energy expenditure was uncorrelated with blood lipids or apolipoproteins. Moderate to vigorous sporting activity, however, appeared to be directly related to high density lipoprotein (HDL) cholesterol (p = 0.06), especially the HDL2 subfraction (p = 0.10). In these data, findings suggest that physical activity is inversely related to myocardial infarction risk, independently of other risk factors for coronary heart disease.

Psychosocial risk factors and nonfatal myocardial infarction

BACKGROUND

Numerous psychosocial factors have been hypothesized to play a role in coronary heart disease. However, existing studies have yielded inconsistent results.

METHODS AND RESULTS

The relations between type A personality as well as suppressed versus expressed anger and risk of nonfatal myocardial infarction (MI) were studied in 340 patients and 340 age-, sex-, and community-matched control subjects. Subjects were interviewed at home to assess behavioral and medical cardiovascular risk factors, and fasting blood samples were obtained. Type A personality was associated with nonfatal MI in crude matched-pair analysis (OR, 1.57; 95% CI, 1.12 to 2.20; P = .008). Adjusting for known cardiovascular risk factors (including treated hypertension, body mass index, treated diabetes, family history of premature MI, physical activity, smoking, alcohol, total calories per day, and saturated fat) did not substantially change the magnitude of the point estimate, although the finding was no longer statistically significant (OR, 1.43; 95% CI, 0.97 to 2.09; P = .069). Further adjustment for lipids, including total cholesterol, total HDL, its subfractions (HDL2, HDL3), LDL, VLDL, and triglycerides, markedly attenuated the association (OR, 1.12; 95% CI, 0.66 to 1.90; P = .687), an effect due almost entirely to HDL cholesterol. Suppressed anger was positively but not statistically significantly associated with increased risk of MI in crude matched-pair analysis (OR, 1.33; 95% CI, 0.98 to 1.81; P = .065), in analysis adjusted for behavioral and medical cardiovascular risk factors (OR, 1.26; 95% CI, 0.89 to 1.78; P = .193), or after adjustment for lipids (OR, 1.11; 95% CI, 0.67 to 1.82; P = .695).

CONCLUSIONS

These findings suggest a possible association of type A but not suppressed anger with risk of nonfatal MI that may be mediated by alterations in HDL cholesterol level. If decreases in HDL are not in the same causal pathway, then the apparent association between type A personality and risk of MI is due to confounding, principally by HDL.

Micronutrients and HIV-1 disease progression

OBJECTIVE

To determine whether nutritional status affects immunological markers of HIV-1 disease progression.

DESIGN

A longitudinal study, to evaluate the relationship between plasma levels of nutrients and CD4 cell counts, along and in combination with beta 2-microglobulin (beta 2M; AIDS index) over an 18-month follow-up.

METHODS

Biochemical measurements of nutritional status including plasma proteins, zinc, iron and vitamins B1, B2, B6, B12 (cobalamin), A, E, C and folate and immunological markers [lymphocyte subpopulations (CD4) and beta 2M] were obtained in 108 HIV-1-seropositive homosexual men at baseline and over three 6-month time periods. Changes in nutrient status (e.g., normal to deficient, deficient to normal), were compared with immunological parameters in the same time periods using an autoregressive model.

RESULTS

Development of deficiency of vitamin A or vitamin B12 was associated with a decline in CD4 cell count (P = 0.0255 and 0.0377, respectively), while normalization of vitamin A, vitamin B12 and zinc was associated with higher CD4 cell counts (P = 0.0492, 0.0061 and 0.0112, respectively). These findings were largely unaffected by zidovudine use. For vitamin B12, low baseline status significantly predicted accelerated HIV-1 disease progression determined by CD4 cell count (P = 0.041) and the AIDS index (P = 0.005).

CONCLUSIONS

These data suggest that micronutrient deficiencies are associated with HIV-1 disease progression and raise the possibility that normalization might increase symptom-free survival.

Fish consumption and cardiovascular disease in the physicians' health study: a prospective study

The authors examined the association between dietary intake of fish and omega 3 fatty acids from seafood and the risk of cardiovascular disease in a prospective cohort study of 21,185 US male physicians who are participants in the Physicians' Health Study. In 4 years of follow-up, there were 281 incident cases of total (fatal and nonfatal) myocardial infarction, 173 cases of stroke, and 121 cardiovascular deaths. There was no evidence for association between dietary intake of fish and any cardiovascular endpoint, including myocardial infarction, stroke, and cardiovascular death. The relative risks of total myocardial infarction, adjusted for age and randomized treatment assignment, for categories of fish intake were: 1.0 for < 1 meal/week (referent), 1.6 (95% confidence interval (Cl) 1.1-2.3) for 1 fish meal/week; 1.4 (95% Cl 1.0-2.0) for 2-4 fish meals/week; and 1.2 (95% Cl 0.6-2.2) for > or = 5 fish meals/week; chi 2 for trend = 0.9, p = 0.34. The relative risks were similar for omega 3 fatty acid intake and for specific types of fish, and did not change after adjustment for history of hypertension, hypercholesterolemia, diabetes mellitus, or angina pectoris, parental history of myocardial infarction before age 60 years, obesity, exercise, smoking, alcohol use, saturated fat intake, and vitamin supplement use. These data do not support the hypothesis that moderate fish consumption lowers the risk of cardiovascular disease.

A prospective study of consumption of carotenoids in fruits and vegetables and decreased cardiovascular mortality in the elderly

Recent evidence suggests that oxidative damage may be involved in atherogenesis, and thus dietary antioxidants, such as beta-carotene, may reduce the risks of cardiovascular disease (CVD). We examined the association between consumption of carotene-containing fruits and vegetables and CVD mortality among 1299 elderly Massachusetts residents who provided dietary information as a part of the Massachusetts Health Care Panel Study. During a mean follow-up of 4.75 years, there were 161 deaths attributable to CVD, 48 of which were due to myocardial infarction. For total CVD death and fatal myocardial infarction, risks were lower among those residents in the highest quartile for consumption of carotene-containing fruits and vegetables as compared with those in the lowest. For death due to CVD, the relative risk (RR) was 0.54 (95% confidence interval (CI), 0.34 to 0.86; P for trend across quartiles, 0.004). For myocardial infarction the RR was 0.25 (95% CI, 0.09 to 0.67; P for trend, 0.002). These observational data are compatible with the hypothesis that increased dietary intake of carotenoids decreases the risks of CVD mortality; however, confounding cannot be ruled out. This hypothesis requires rigorous evaluation in randomized trials of sufficient size to detect reliably whether carotenoids confer small-to-moderate but clinically important protection against CVD.

A secondary prevention trial of antioxidant vitamins and cardiovascular disease in women. Rationale, design, and methods. The WACS Research Group

The evidence for a potential benefit of antioxidant vitamins in the prevention and therapy of atherosclerotic disease is derived from laboratory, clinical, and observational epidemiologic studies but remains inconclusive. Data from randomized clinical trials are sparse, particularly for women. Therefore, it is both timely and important to conduct large-scale primary and secondary prevention trials of antioxidants and cardiovascular disease (CVD). The Women's Antioxidant and Cardiovascular Study (WACS) is a randomized, double-blind, placebo-controlled secondary prevention trial of the balance of benefits and risks of antioxidant vitamins (vitamins E and C, and beta-carotene) among 8000 women with preexisting CVD. This secondary prevention trial will be conducted as a companion to the recently started Women's Health Study, a primary prevention trial of vitamin E and beta-carotene, as well as aspirin. In the WACS, US female health professionals aged 40 years and older with a history of myocardial infarction, angina pectoris, coronary revascularization, stroke, transient cerebral ischemia, carotid endarterectomy, or peripheral artery surgery will be randomly assigned, utilizing a 2 x 2 x 2 factorial design, to receive vitamin E, vitamin C, beta-carotene, and/or placebo. Cardiovascular end points include nonfatal myocardial infarction, nonfatal stroke, coronary revascularization procedures, and total CVD mortality. The present article describes the rationale, design, and methods of the trial.

Man-made vitreous fibers and risk of respiratory system cancer: a review of the epidemiologic evidence

Because asbestos has been demonstrated to cause lung cancer, the issue regarding safety of other fibers, including man-made vitreous fibers (MMVF), has been raised. We reviewed the available evidence, in particular the epidemiologic data, on MMVF and the risk of respiratory system cancer. Glass fibers (especially glass wool) have been studied most extensively. Taken together, the data indicate that among those occupationally exposed, glass fibers do not appear to increase risk of respiratory system cancer. Of six studies that specifically examined rock and slag wool workers, three reported excesses in respiratory system cancer among such workers. Two of these three studies, however, did not control for cigarette smoking, a powerful predictor of such cancers. There are no published studies, in humans, of refractory ceramic fibers. Future studies evaluating the potential of MMVF to increase risk of respiratory system cancer will not add to existing knowledge if investigators do not address potential confounding by cigarette smoking and other workplace carcinogens.

Migraine and subsequent risk of stroke in the Physicians' Health Study

OBJECTIVE

To evaluate, in a prospective design, whether migraine is an independent risk factor for subsequent stroke.

DESIGN

Evaluated as part of the Physicians' Health Study, a randomized, double-blind, placebo-controlled trial of aspirin and beta-carotene in the primary prevention of cardiovascular disease and cancer begun in 1982. The aspirin component of the study was terminated in 1988, with average follow-up of 60.2 months.

SETTING

Conducted by mail among male physicians throughout the United States.

PARTICIPANTS

A total of 22,071 US male physicians aged 40 to 84 years in 1982 with no prior history of cancer or cardiovascular diseases who were enrolled in the Physicians' Health Study.

INTERVENTIONS

Participants were randomized to receive 325 mg of aspirin or aspirin placebo every other day and to receive 50 mg of beta-carotene or placebo on alternate days.

MAIN OUTCOME MEASURES

The primary outcomes of the Physicians' Health Study were cardiovascular disease and cancer. Because stroke was a main outcome, this provided the opportunity to evaluate the association between migraine headaches and stroke.

RESULTS

Physicians reporting migraine (n = 1479) had significantly increased risks of subsequent total stroke and ischemic stroke compared with those not reporting migraine. After adjustment for age, aspirin and beta-carotene treatment assignment, and a number of cardiovascular risk factors, the relative risks were 1.84 (95% confidence interval, 1.06 to 3.20) for total stroke and 2.00 (95% confidence interval, 1.10 to 3.64) for ischemic stroke. There were too few hemorrhagic strokes in the study to evaluate this end point. No associations were seen between ordinary nonmigraine headache and subsequent stroke or between migraine and subsequent myocardial infarction or cardiovascular death.

CONCLUSION

These data raise the possibility that vascular events associated with migraine may also have causative importance in stroke but require confirmation in other studies specifically designed to evaluate this question.

beta-carotene and cancer chemoprevention

Evidence supports the potential role of beta-carotene in cancer prevention. Basic research has demonstrated that beta-carotene can trap organic free radicals and/or deactivate excited oxygen molecules which may have an anticancer effect by preventing tissue damage. Although observational epidemiologic studies are not entirely consistent, many show an inverse association between dietary intake or blood levels of beta-carotene and subsequent cancer risk. Two large-scale randomized trials of beta-carotene have been completed. A Finnish trial demonstrated no benefit of beta-carotene among middle-aged male smokers, with those assigned to this supplement in fact experiencing an increased risk of lung cancer. However, because of the long latency period for cancer, which may be a decade or more, the six-year duration of treatment in this trial may have been inadequate to detect an anticancer effect. A Chinese trial demonstrated a modest reduction in cancer mortality from a combined regimen of beta-carotene, vitamin E, and selenium. The effect of the individual agents could not be assessed, and because the trial was carried out among a nutritionally deficient population, its results may not have direct relevance to well-nourished individuals. Several additional large-scale trials of beta-carotene are ongoing. The Physicians' Health Study, which is testing beta-carotene among 22,071 US male physicians, will have an average duration of treatment of 12.5 years at its scheduled termination in late 1995. Data in women will be available from the Women's Health Study, which began in 1992, and will randomize approximately 40,000 US female health professionals.(ABSTRACT TRUNCATED AT 250 WORDS)

Adherence to aspirin in the prevention of myocardial infarction. The Physicians' Health Study

BACKGROUND

The primary aim of this article was to explore, in subgroup analyses, whether participants with differing frequencies of aspirin consumption in a randomized, double-blind, placebo-controlled, primary prevention trial had different magnitudes of benefit in the prevention of myocardial infarction. Secondary aims were to identify factors associated with adherence and to examine the relationship of adherence with cardiovascular outcomes in the placebo group.

METHODS

The Physicians' Health Study randomized 22071 US male physicians who were free of myocardial infarction and cerebrovascular disease at baseline. The average follow-up during the aspirin component of the trial was 60.2 months. Baseline cardiovascular risk factors and adherence to therapy during the trial were assessed by questionnaire; cardiovascular outcomes were reported by questionnaire and confirmed by record review by an Endpoints Committee.

RESULTS

Several cardiovascular disease risk factors assessed at baseline were related to poor adherence (taking < 50% of study tablets): cigarette smoking, obesity, lack of exercise, and history of angina. After adjusting for baseline differences in risk factors, participants in the aspirin group with excellent adherence (taking at least 95% of study tablets) had a statistically significant 51% reduction in myocardial infarction compared with those with excellent adherence in the placebo group. Those in the aspirin group with poor adherence had a smaller, non-significant reduction in risk of myocardial infarction (a 17% reduction associated with taking < 50% of study tablets). In the placebo group better adherence was not associated with decreased risk of myocardial infarction, but was strongly associated with decreased risk of death.

CONCLUSIONS

These subgroup data raise the possibility that a less than alternate day aspirin regimen may yield lower benefits in the prevention of myocardial infarction. Alternate explanations are that these analyses reflect either the play of chance or effects of uncontrolled confounding since comparisons were no longer randomized. Randomized trials are necessary to address the question of frequency of administration of aspirin to achieve optimal benefits in primary prevention of myocardial infarction.

Contributions of observational evidence and clinical trials in cancer prevention

Observational studies and randomized trials provide relevant and complementary information to a totality of evidence on which to base rational clinical decision making for patients and overall health policy for the general population. Observational studies are particularly useful for detecting moderate to large effects. The 15- to 20-fold greater risk of lung cancer among long term cigarette smokers was established by case-control and prospective cohort studies. The approximate 80% increased risk of coronary heart disease associated with current smoking also has been reliably demonstrated in observational studies. However, as the relative risk gets smaller, there is increasing concern that unmeasured or unknown confounding variables may account for all or part of any observed association. For these reasons, reliable inferences about interventions likely to confer small to moderate benefits will emerge only from randomized trials of sufficient sample size and duration of treatment and follow-up. Dietary variables have been postulated to account for as much as 35% of all human cancers. However, the hypothesized benefit of any specific dietary constituent, such as the antioxidant beta-carotene, is likely to be modest in size, on the order of a 20-30% reduction in risk. Therefore, although a large number of observational studies have demonstrated that individuals with higher dietary intakes or blood levels of beta-carotene have lower risks of cancer, only randomized trials can address this hypothesis definitively. Such trials, however, must be of sufficient duration to allow for the development of an anticancer effect. This may mean a decade or more based on the analogy with smoking cessation and decreased risks of lung cancer. Several ongoing large-scale trials are testing beta-carotene and other promising cancer chemoprevention agents, and their results will provide clear evidence on the balance of benefits and risks of these interventions.

Aspirin in the primary prevention of cardiovascular disease

The ability of aspirin to reduce cardiovascular disease risks has been tested in randomized trials in a wide range of patient categories. There are clear benefits of aspirin on nonfatal myocardial infarction, nonfatal stroke, and vascular death among patients with prior manifestations of cardiovascular disease, such as myocardial infarction, unstable angina, and stroke. Aspirin is also beneficial to those in the acute phase of evolving myocardial infarction. In primary prevention, there is a clear reduction in myocardial infarction in men. A large-scale primary prevention trial in women is presently underway.

Confirmation of self-reported cataract in the Physicians' Health Study

Large-scale prospective studies of disease development often rely on self-reported data. To assess the accuracy of self-reports of cataract, we compared the self-reports with medical record data obtained from diagnosing ophthalmologists and optometrists for participants in the Physicians' Health Study, a randomized trial of aspirin and beta-carotene among 22,071 male U.S. physicians aged 40-84 years. A report of cataract, defined as a positive response to a question about whether cataract had ever been diagnosed in either eye and the date of diagnosis, was found to be a very good indicator of lens opacification but was not a good indicator of an incident, age-related opacity that reduced visual acuity. These results indicate that in large prospective studies of clinically significant cataract, where examination of all study participants is not feasible and self-reported data are used, additional documentation to supplement the self-reports should be obtained and strict diagnostic criteria applied to minimize the likely effects of misclassification.

Height, lung function, and mortality from cardiovascular disease among the elderly

The relation between height and death from cardiovascular disease was studied in a cohort of 3,809 persons aged 65 years or older (85% of eligible individuals) enrolled in a population survey in 1982-1983 in East Boston, Massachusetts. Self-reported height and weight were obtained, and peak expiratory flow rate (PEFR) was measured using a mini-Wright peak flow meter (Armstrong Industries, North Brook, Illinois). Vital status and cause of death were obtained through 1988. The median height was 62 inches in women and 66 inches in men. After adjustment for age, body mass index, and cigarette smoking, the risk of cardiovascular death decreased with quintile of height in women, with relative risks of 1.65, 1.16, 1.15, 0.76, and 1.00 over successive quintiles, with the tallest as the referent (p trend = 0.015). The trend in men was not as strong, with relative risks of 1.22, 0.77, 0.90, 0.98, and 1.00 from the shortest to the tallest quintiles (not significant). In both men and women, the strongest association was found with height and height squared, indicating a curvilinear relation. Height remained a predictor in women after adjustment for PEFR and other risk factors. These data suggest that a relation between height and cardiovascular death that is not mediated by lung function exists in the elderly, at least among women.

The use of vitamin supplements and the risk of cataract among US male physicians

OBJECTIVES

The purpose of this study was to examine prospectively the association between reported use of vitamin supplements and risk of cataract and cataract extraction.

METHODS

The study population consisted of 17,744 participants in the Physicians' Health Study, a randomized trial of aspirin therapy and beta-carotene among US male physicians 40 to 84 years of age in 1982 who did not report cataract at baseline and provided complete information about vitamin supplementation and other risk factors for cataract. Self-reports of cataract and cataract extraction were confirmed by medical record review.

RESULTS

During 60 months of follow-up, there were 370 incident cataracts and 109 cataract extractions. In comparison with physicians who did not use any supplements, those who took only multivitamins had a relative risk of cataract of 0.73 after adjustment for other risk factors. For cataract extraction, the corresponding relative risk was 0.79. Use of vitamin C and/or E supplements alone was not associated with a reduced risk of cataract, but the size of this subgroup was small.

CONCLUSIONS

These data suggest that men who took multivitamin supplements tended to experience a decreased risk of cataract and support the need for rigorous testing of this hypothesis in large-scale randomized trials in men and women.

Randomized trials of primary prevention of cardiovascular disease in women. An investigator's view

In recent years, increasing attention has focused on the need for more research to be conducted in women on health issues directly relevant to women. No one would disagree that the need for such studies is both crucial and timely. However, while the need for more research in women is urgent, the planning and conduct of such studies must always be driven by good science. Specifically, investigations in women may have unique and important scientific and logistic problems which must be recognized and addressed. However, if the trials are well designed and conducted, they will provide a sound and reliable body of data upon which to base rational clinical decision making and public health recommendations for women from women. These general issues are discussed in the context of a particular trial, the Women's Health Study, a randomized trial of the risks and benefits of low-dose aspirin, beta-carotene and vitamin E in the primary prevention of cardiovascular disease and cancer among healthy women.

The benefits of aspirin in acute myocardial infarction. Still a well-kept secret in the United States

Acute myocardial infarction (MI) remains far and away the leading cause of death in the United States, and is responsible for approximately 500,000 annual fatalities. However, mortality due to MI has declined substantially in recent decades, owing to advances in treatment as well as prevention. Low-dose aspirin as well as thrombolytic therapy given during acute evolving MI each decrease mortality by about one quarter. Both therapies remain underutilized in the United States. Aspirin can be given to virtually all patients, has a far more favorable safety profile than thrombolysis, and confers a comparable benefit at a small fraction of the cost of thrombolytic agents. The more widespread use of aspirin in acute MI is one of the most important and timely clinical challenges in the United States.

Trans-fatty acids intake and risk of myocardial infarction

BACKGROUND

Concern that trans-fatty acids formed in the partial hydrogenation of vegetable oils may increase the risk of coronary disease has existed for several decades, but direct evidence on this relation in humans is limited.

METHODS AND RESULTS

With a case-control design, we studied the association between intake of trans-fatty acids and a first acute myocardial infarction among 239 patients admitted to one of six hospitals in the Boston area and 282 population control subjects. Intake of trans-fatty acids was estimated using a previously validated food frequency questionnaire. After adjustment for age, sex, and energy intake, intake of trans-fatty acids was directly related to risk of myocardial infarction (relative risk for highest compared with lowest quintile, 2.44; 95% confidence interval, 1.42, 4.19; for trend P < .0001). This relation remained highly significant after adjustment for established coronary risk factors, multivitamin use, and intake of saturated fat, monounsaturated fat, linoleic acid, dietary cholesterol, vitamins E and C, carotene, and fiber. Intake of margarine--the major source of trans-isomers--was significantly associated with risk of myocardial infarction.

CONCLUSIONS

These data support the hypothesis that intake of partially hydrogenated vegetable oils may contribute to the risk of myocardial infarction.

Moderate alcohol intake, increased levels of high-density lipoprotein and its subfractions, and decreased risk of myocardial infarction

BACKGROUND

Previous studies have suggested that moderate alcohol intake exerts a protective effect against coronary heart disease. Alterations in plasma lipoprotein levels represent one plausible mechanism of this apparent protective effect.

METHODS

We therefore examined the interrelation among alcohol consumption, plasma lipoprotein levels, and the risk of myocardial infarction in 340 patients who had had myocardial infarctions and an equal number of age- and sex-matched controls. The case patients were men or women less than 76 years of age with no history of coronary disease who were discharged from one of six hospitals in the Boston area with a diagnosis of a confirmed myocardial infarction. Alcohol consumption was estimated by means of a food-frequency questionnaire.

RESULTS

We observed a significant inverse association between alcohol consumption and the risk of myocardial infarction (P for trend, < 0.001 after control for known coronary risk factors). In multivariate analyses, the relative risk for the highest intake category (subjects who consumed three or more drinks per day) as compared with the lowest (those who had less than one drink a month) was 0.45 (95 percent confidence interval, 0.26 to 0.80). The levels of total high-density lipoprotein cholesterol (HDL) and its HDL2 and HDL3 subfractions were strongly associated with alcohol consumption (P for trend, < 0.001 for each). The addition of HDL or either of its subfractions to the multivariate model substantially reduced the inverse association between alcohol intake and myocardial infarction, whereas the addition of the other plasma lipid measurements did not materially alter the relation.

CONCLUSIONS

These data confirm the inverse association of moderate alcohol intake with the risk of myocardial infarction and support the view that the effect is mediated, in large part, by increases in both HDL2 and HDL3.

Height and incidence of cardiovascular disease in male physicians

BACKGROUND

An inverse association between height and risk of coronary heart disease (CHD) has been reported in several case-control and cohort studies, but the reasons for the association remain uncertain. We evaluated this association among 22,071 male physicians, a population homogeneous for high educational attainment and socioeconomic status in adulthood.

METHODS AND RESULTS

The study population was comprised of participants in the Physicians' Health Study, a randomized, double-blind, placebo-controlled trial of low-dose aspirin and beta-carotene in the primary prevention of cardiovascular disease and cancer among US male physicians, aged 40 to 84 years, in 1982. Participants were classified into five height categories at study entry, from shortest to tallest, and were followed an average of 60.2 months to determine the incidence of myocardial infarction (MI), stroke, and death from cardiovascular disease. Men in the tallest (> or = 73 in. or 185.4 cm) compared with the shortest (< or = 67 in. or 170.2 cm) height category had a 35% lower risk of MI (relative risk, 0.65; 95% confidence interval, 0.44 to 0.99; P = .04), after adjusting for known cardiovascular risk factors. Further, a marginally significant inverse trend (P trend = .05) across the height categories was observed. Although the relationship was not strictly linear, for every inch of added height, there was an approximate 2% to 3% decline in risk of MI. In contrast, men in the tallest compared with the shortest height category had only small and nonsignificant decreases in risk of stroke and cardiovascular death. While no significant trend in risks of these end points across the height categories was observed, the numbers of events for these end points were far less than for MI, and thus the confidence intervals were wide.

CONCLUSIONS

These data indicate that height is inversely associated with subsequent risk of MI. At this time, a few mechanisms are plausible, but none are convincing. Other epidemiological and basic research efforts are needed to explore a variety of physiological correlates of height that may be responsible for mediating the height-MI association. In the meantime, while height is not modifiable, it is easy to measure and may be useful to evaluate CHD disease risk profiles and target lifestyle interventions.

Modification of increasing systolic blood pressure in the elderly during the 1980s

The authors examined whether changing attitudes and approaches to modifying blood pressure during the 1980s affected the previously described pattern of increasing systolic blood pressure in the elderly which continues through the ninth decade of life. In 1982-1983, a door-to-door census identified 4,497 community-dwelling residents of East Boston, Massachusetts aged 65 and over, of whom 3,657 had baseline blood pressure assessments. Follow-up blood pressure assessments occurred in 1985-1986 and in 1988-1989. Cross-sectionally, the relation of age with systolic blood pressure was quadratic with levels predicted to increase until about age 84 after which they were lower among oldest-old survivors. Longitudinally, mean age-sex-adjusted systolic blood pressure was 3.3 mmHg lower in 1985-1986 compared with 1982-1983 (95 percent confidence interval (CI) 2.4-4.2 mmHg) and 10.6 mmHg lower in 1988-1989 compared with 1982-1983 (95 percent CI 9.5-11.7 mmHg). Utilization of antihypertension medications increased over time and accounted for some, but not all, of the observed decreases in systolic blood pressure. Large shifts occurred in the use of specific antihypertension medications including increases in use of angiotensin converting enzyme inhibitors and calcium entry blockers and decreases in use of thiazide diuretics. Previously described trends for increasing systolic blood pressure in the elderly were reversed during the 1980s when the continued decline in cardiovascular mortality was greatest among the elderly.

Antiplatelet therapy and risk of stroke

Antiplatelet therapy, especially with aspirin, reduces the risks of occlusive vascular disease, including ischemic stroke. In an overview of 25 trials of antiplatelet therapy in patients with prior cardiovascular disease, antiplatelet treatment reduced subsequent nonfatal stroke by 27% (P = 0.0001), nonfatal myocardial infarction by 32% (P = 0.0001), and all vascular deaths by 15% (P = 0.0003), with no evidence that other antiplatelet agents were more effective than aspirin, or that higher aspirin doses (900 to 1500 mg daily) were more effective than 300 mg, the lowest daily dose tested. If begun during the acute phase of myocardial infarction, aspirin reduces nonfatal stroke by 46% (P < 0.01) and vascular deaths by 23% (P < 0.00001) after 5 weeks. In primary prevention, currently available data are inconclusive regarding the effect of aspirin therapy on stroke. However, any potential benefit on ischemic stroke must be weighed against the possibility that aspirin could increase the risk of the less common, but clinically more severe, strokes of hemorrhagic etiology.

Low-dose aspirin and incidence of colorectal tumors in a randomized trial

BACKGROUND

Laboratory, clinical, and epidemiologic studies have recently suggested that regular use of aspirin can reduce colorectal cancer incidence or mortality. However, observational epidemiologic analyses have had limited opportunity to control for confounding bias or to specify aspirin doses used.

PURPOSE

Our purpose was to examine the relationship between regular use of low-dose aspirin and incidence of invasive and noninvasive colorectal tumors by utilizing data from the Physicians' Health Study, a randomized, double-blinded, placebo-controlled trial of aspirin and beta carotene. We also attempted to determine whether invasive cancers among aspirin users were associated with rectal bleeding and early stage at diagnosis.

METHODS

The Physicians' Health Study includes 22071 U.S. male physicians. The aspirin arm was terminated in 1988 after a mean follow-up of 5 years. Stage at diagnosis and signs and/or symptoms during presentation were abstracted from medical records. Cox proportional hazards models were used to estimate relative risk (RR), 95% confidence intervals (CIs), and the association between aspirin and bleeding. Differences between aspirin and placebo groups in tumor risk over time were visualized with Kaplan-Meier curves. We assessed the association between aspirin and stage at diagnosis with a Mann-Whitney rank sum statistic for non-parametric comparison of two ordinal distributions.

RESULTS

The RR of developing colorectal cancer for aspirin compared with placebo was 1.15 (95% CI = 0.80-1.65). For in situ cancers and polyps, the RR was 0.86 (95% CI = 0.68-1.10). There was no significant trend for decreasing RR by year of follow-up for invasive cancers (P = .09) or noninvasive tumors (P = .96). Aspirin and placebo groups did not differ in stage or prevalence of rectal bleeding at diagnosis.

CONCLUSIONS

Regular aspirin use, at a dose adequate for preventing myocardial infarction, was not associated with a substantial reduction in the incidence of colorectal cancer during 5 years of randomized treatment and follow-up. A small decrease in polyps in the aspirin group could not be reliably distinguished from a chance association. Our results suggest that among low-dose aspirin users, (a) colorectal cancer mortality is not likely to be reduced by earlier detection and (b) incidence is not likely to be increased due to aspirin-induced gastrointestinal bleeding.

IMPLICATIONS

The potential for a benefit from higher doses of aspirin or longer duration of use should be addressed by more detailed observational epidemiologic studies and prevention trials with longer follow-up of randomized participants.

Occupation and risk of nonfatal myocardial infarction

BACKGROUND

While some analytic studies have suggested that individuals in occupations representing higher compared with lower socioeconomic status have a decreased risk of coronary heart disease, it is unclear whether occupation itself has an etiologic role in the development of coronary heart disease or whether differences in as yet uncontrolled coronary risk factors may account for these differences in risk.

METHODS

White-collar vs blue-collar occupation and risk of coronary heart disease was evaluated among 230 male patients hospitalized for a first myocardial infarction and 222 control subjects of the same age, sex, and neighborhood of residence. Information on coronary risk factors was obtained from home interviews, and blood specimens were drawn to test lipid and lipoprotein levels. Usual occupation was dichotomized into white-collar and blue-collar occupation according to the Edwards' classification.

RESULTS

The relative risk of myocardial infarction of white-collar compared with blue-collar workers was 0.74 (95% confidence interval, 0.46 to 1.19) after controlling for age, cigarette smoking, family history of premature myocardial infarction, history of treatment for high blood pressure, body mass index, history of diabetes, alcohol consumption, type A personality, leisure-time physical activity, total calories, and percentage of calories consumed as saturated fat. However, there was no residual association after control for high-density lipoprotein cholesterol yielding a relative risk of 0.98 (95% confidence interval, 0.59 to 1.63).

CONCLUSIONS

These results suggest that white-collar occupation per se does not appear to protect from coronary heart disease. Any apparent protective effect on myocardial infarction that has been previously observed in white-collar compared with blue-collar workers may be attributable to differences in high-density lipoprotein cholesterol levels.

A prospective study of cigarette smoking and risk of cataract in men

OBJECTIVE

To examine the association between cigarette smoking and the incidence of cataract.

DESIGN, SETTING, AND PARTICIPANTS

The design was a prospective cohort study using data from the Physicians' Health Study, a randomized trial of aspirin and beta carotene among 22,071 US male physicians aged 40 to 84 years that began in 1982. This analysis includes the 17,824 physicians who did not report cataract at baseline and did provide complete risk factor information. Based on information reported at baseline, 10% were current smokers, 39% were past smokers, and 51% were never smokers.

MAIN OUTCOME MEASURE

An incident cataract was defined as a self-report confirmed by medical record review to have been first diagnosed after randomization, age-related in origin, and responsible for a decrease in best corrected visual acuity to 20/30 or worse.

MAIN RESULTS

During 60 months of follow-up, 557 incident cataracts among 371 participants were confirmed. Compared with never smokers, current smokers of 20 or more cigarettes per day had a statistically significant increase in the risk of cataract (relative risk [RR], 2.16; 95% confidence interval [Cl], 1.46 to 3.20; P less than .001). Similar results were obtained after simultaneously controlling for other potential cataract risk factors in a logistic regression model (RR, 2.05; 95% Cl, 1.38 to 3.05; P less than .001). Among the 557 eyes with cataract, nuclear sclerotic changes were present in 442 while posterior subcapsular changes were present in 204. After controlling for other potential cataract risk factors, current smokers of 20 or more cigarettes per day had statistically significant increases in nuclear sclerosis (RR, 2.24; 95% Cl, 1.47 to 3.41; P less than .001) and posterior subcapsular (RR, 3.17; 95% Cl, 1.81 to 5.53; P less than .001) cataract. Past smokers had an elevated risk of posterior subcapsular (RR, 1.44; 95% Cl, 0.97 to 2.13; P = .07) but not nuclear sclerosis cataract. For current smokers of fewer than 20 cigarettes per day, no increased risks were observed of total, nuclear sclerosis, or posterior subcapsular cataract.

CONCLUSIONS

These data provide support for the hypothesis that cigarette smoking increases the risk of developing both nuclear sclerosis and posterior subcapsular cataract.

Low-dose aspirin and subsequent peripheral arterial surgery in the Physicians' Health Study

In the US Physicians' Health Study the early termination of the aspirin arm has provided the opportunity to test the hypothesis that low-dose aspirin (325 mg on alternate days) might affect the subsequent occurrence of peripheral arterial surgery. In the study, a randomised double-blind placebo-controlled trial among 22,071 healthy US male physicians aged 40-84, there were, during an average of 60.2 months of treatment and follow-up, 56 participants who underwent peripheral arterial surgery (20 aspirin, 36 placebo). The relative risk of peripheral artery surgery in the aspirin group was 0.54 (95% confidence intervals 0.30-0.95; p = 0.03). These data indicate that chronic administration of low-dose aspirin to apparently healthy men reduced the need for peripheral arterial surgery.

Comparison of delay times to hospital presentation for physicians and nonphysicians with acute myocardial infarction

To evaluate whether patients who recognize the symptoms of myocardial ischemia and have easy access to medical care have shortened time delays between onset of symptoms and hospital presentation, the total time interval between symptom onset and hospital arrival for 258 U.S. male physicians experiencing a first acute myocardial infarction (AMI) in the Physicians' Health Study (PHS) was compared with that of a comparable group of 240 men enrolled in the U.S. component of the Second International Study of Infarct Survival (ISIS-2), as well as with those of previously published series of patients with AMI. For patients presenting for medical care within 24 hours of symptom onset, the median time delay from onset of symptoms to presentation for medical care was 1.8 hours in the PHS, and 4.9 hours in the U.S. component of ISIS-2 (p less than 0.001). Furthermore, 56% of participants in the PHS presented for medical care within 2 hours and 72% within 4 hours of symptom onset compared with 20% (p less than 0.001) and 44% (p less than 0.001), respectively, for ISIS-2 participants. In previously published series, the average time to presentation was comparable to that in the ISIS-2 trial, with variation depending on country of origin and on local population density. The median time to medical presentation in any previous series was not shorter than that in the PHS. Thus, physicians in the PHS had significantly shorter time delays between onset of symptoms and presentation for medical care. This difference may help explain the far lower than expected cardiovascular mortality rates among physician participants in the PHS.(ABSTRACT TRUNCATED AT 250 WORDS)