Prospective cohort study of antioxidant vitamin supplement use and the risk of age-related maculopathy

In a prospective cohort study, the authors examined whether self-selection for antioxidant vitamin supplement use affects the incidence of age-related maculopathy. The study population consisted of 21,120 US male physician participants in the Physicians' Health Study I who did not have a diagnosis of age-related maculopathy at baseline (1982). During an average of 12.5 person-years of follow-up, a total of 279 incident cases of age-related maculopathy with vision loss to 20/30 or worse were confirmed by medical record review. In multivariate analysis, as compared with nonusers of supplements, persons who used vitamin E supplements had a possible but nonsignificant 13% reduced risk of age-related maculopathy (relative risk = 0.87, 95 percent confidence interval (CI) 0.53-1.43), while users of multivitamins had a possible but nonsignificant 10% reduced risk (relative risk = 0.90, 95% CI 0.68-1.19). Users of vitamin C supplements had a relative risk of 1.03 (95% CI 0.71-1.50). These observational data suggest that among persons who self-select for supplemental use of antioxidant vitamin C or E or multivitamins, large reductions in the risk of age-related maculopathy are unlikely. Randomized trial data are accumulating to enable reliable detection of the existence of more plausible small-to-moderate benefits of these agents alone and in combination on age-related maculopathy.

Increased pulse pressure and risk of heart failure in the elderly

CONTEXT

Arterial stiffness increases with age. Thus, pulse pressure, an index of arterial stiffening, may predict congestive heart failure (CHF) in the elderly.

OBJECTIVE

To study prospectively the association between pulse pressure and risk of CHF.

DESIGN

Prospective cohort study.

SETTING

The community-based East Boston Senior Health Project, East Boston, Mass.

PATIENTS

A total of 1621 men and women (mean [SD] age, 77.9 [5.0] years) free of CHF who had blood pressure measurements taken in 1988-1989 and were followed up for 3.8 years.

MAIN OUTCOME MEASURE

Incidence of CHF as ascertained by hospital discharge diagnosis (n = 208) and death certificates (n = 13).

RESULTS

After controlling for age, sex, mean arterial pressure, history of coronary heart disease, diabetes mellitus, atrial fibrillation, valvular heart disease, and antihypertensive medication use, pulse pressure was an independent predictor of CHF. For each 10-mm Hg elevation in pulse pressure, there was a 14% increase in risk of CHF (95% confidence interval, 1.05-1.24; P = .003). Those in the highest tertile of pulse pressure (>67 mm Hg) had a 55% increased risk of CHF (P=.02) compared with those in the lowest (<54 mm Hg). Pulse pressure was more predictive than systolic blood pressure alone and was independent of diastolic blood pressure.

CONCLUSION

Pulse pressure, an easily measurable correlate of pulsatile hemodynamic load, is an independent predictor of risk of CHF in this elderly cohort.

Birthweight and the risk for type 2 diabetes mellitus in adult women

BACKGROUND

Previous reports have suggested an association between birthweight and type 2 diabetes mellitus.

OBJECTIVE

To investigate the association between birthweight and type 2 diabetes in a large cohort of adult women, taking into account potential explanatory factors in childhood and adult life.

DESIGN

Cohort study. Birthweight was ascertained at the end of follow-up.

SETTING

The Nurses' Health Study, a cohort of 121,701 U.S. women born from 1921 to 1946 who have been followed since 1976.

PARTICIPANTS

69,526 women in the Nurses' Health Study who were free of diabetes at baseline and reported their own birthweight on the 1992 questionnaire.

MEASUREMENT

2123 cases of confirmed type 2 diabetes diagnosed from 1976 to 1992.

RESULTS

Low birthweight was associated with increased risk for type 2 diabetes. Age-adjusted relative risks suggested a reverse J-shape association between birthweight and risk for type 2 diabetes. However, after adjustment for adult body mass index and maternal history of diabetes, an inverse association across the entire range of birthweight became apparent; compared with the reference group, relative risks by ascending birthweight category were 1.83 (95% CI, 1.55 to 2.16) for birthweight less than 5.0 lb, 1.76 (CI, 1.49 to 2.07) for birthweight 5.0 to 5.5 lb, 1.23 (CI, 1.11 to 1.37) for birthweight 5.6 to 7.0 lb, 0.95 (CI, 0.82 to 1.10) for birthweight 8.6 to 10.0 lb, and 0.83 (CI, 0.63 to 1.07) for birthweight of more than 10 lb (P for trend < 0.001). Adjustment for ethnicity, childhood socioeconomic status, and adult lifestyle factors did not substantially alter this association. The association between birthweight and risk for type 2 diabetes was strongest among women whose mothers had no history of diabetes.

CONCLUSIONS

Birthweight is inversely associated with risk for type 2 diabetes during adulthood. Examination of prenatal nutrition and other potential in utero determinants of both birthweight and risk for type 2 diabetes may yield new means to prevent type 2 diabetes.

Beta-carotene supplementation: a good thing, a bad thing, or nothing?

Available data from several completed large-scale randomized trials indicate that beta-carotene supplementation for durations up to 12 years has no overall benefit in well-nourished populations on the incidence of cardiovascular disease or the middle-to-late stages of carcinogenesis. Several important questions, however, remain unanswered. The post-trial follow-up of completed trials, together with the results of several ongoing trials of beta-carotene supplementation, will contribute reliable information to the totality of evidence from basic research, animal studies, observational epidemiologic studies, and completed trials, thus allowing more rational clinical decisions for individual patients and policy decisions for the health of the general public.

Prospective evaluation of the angiotensin-converting enzyme insertion/deletion polymorphism and the risk of stroke

BACKGROUND

The D/I polymorphism of the ACE gene has been studied in relation to a variety of cardiovascular disorders, including stroke. A number of small studies have been conducted, with inconsistent results. We investigated the association between ACE genotype and the incidence of stroke in a large, prospective, matched case-control sample from the Physicians' Health Study.

METHODS AND RESULTS

In the Physicians' Health Study, 348 subjects who had been apparently healthy at enrollment suffered a stroke during 12 years of follow-up, as determined from medical records and autopsy. A total of 348 cases were matched by age, time of randomization, and smoking habit to an equal number of controls (who had remained free of stroke). The D/I polymorphism was determined by polymerase chain reaction. Data were analyzed for the entire nested case-control sample, and also among a subgroup without a history of hypertension or diabetes mellitus, considered to be at low conventional risk (207 cases and 280 controls). All observed genotype frequencies were in Hardy-Weinberg equilibrium. The relative risk associated with the D allele was 1.11 (95% CI, 0.90 to 1.37; P=0.35), assuming an additive model in the matched analysis. Additional analyses assuming dominant or recessive effects of the D allele, as well as the analysis after stratification for low-risk status, showed no material as a statistically significant association.

CONCLUSIONS

The results of this large, prospective study indicate that the ACE D/I gene polymorphism is not associated with subsequent risk of stroke.

Coffee and tea intake and the risk of myocardial infarction

The authors investigated the association of caffeinated coffee, decaffeinated coffee, and tea with myocardial infarction in a study of 340 cases and age-, sex-, and community-matched controls. The odds ratio for drinking > or = 4 cups/day of caffeinated coffee versus drinking < or = 1 cup/week was 0.84 (95% confidence interval (CI) 0.49-1.42) after adjustment for coronary risk factors (1 cup = 237 ml). The odds ratio for drinking > 1 cup/day of decaffeinated coffee versus nondrinkers was 1.25 (95% CI 0.76-2.04). For tea, the odds ratio for drinking > or = 1 cup/day versus nondrinkers was 0.56 (95% CI 0.35-0.90). In these data, only tea was associated with a lower risk of myocardial infarction.

Exercise and risk of stroke in male physicians

BACKGROUND AND PURPOSE

From a physiological perspective, physical activity might be expected to decrease the risk of developing stroke. However, epidemiological studies of physical activity and stroke risk have yielded divergent findings. We therefore sought to examine the association between exercise and stroke risk.

METHODS

This was a prospective cohort study of 21 823 men, followed up for an average of 11.1 years. Participants were from the Physicians' Health Study, a randomized trial of low-dose aspirin and beta carotene. Men, aged 40 to 84 years at baseline, were free of self-reported myocardial infarction, stroke, transient ischemic attack, and cancer. At baseline, they reported on the frequency of exercise vigorous enough to work up a sweat. Stroke occurrence was reported by participants and confirmed after medical record review (n=533). We used Cox proportional hazards regression to analyze the data.

RESULTS

With adjustment for age, treatment assignment, smoking, alcohol intake, history of angina, and parental history of myocardial infarction, the relative risks of total stroke associated with vigorous exercise <1 time, 1 time, 2 to 4 times, and >/=5 times per week at baseline were 1.00 (referent), 0.79 (95% confidence interval [CI], 0.61 to 1. 03), 0.80 (95% CI, 0.65 to 0.99), and 0.79 (95% CI, 0.61 to 1.03), respectively; P for trend=0.04. In subgroup analyses, the inverse association appeared stronger with hemorrhagic than ischemic stroke. When we additionally adjusted for body mass index, history of hypertension, high cholesterol, and diabetes mellitus, corresponding relative risks for total stroke were 1.00 (referent), 0.81 (95% CI, 0.61 to 1.07), 0.88 (95% CI, 0.70 to 1.10), and 0.86 (95% CI, 0.65 to 1.13), respectively; P for trend=0.25.

CONCLUSIONS

Exercise vigorous enough to work up a sweat is associated with decreased stroke risk in men. In the present study, the inverse association with physical activity appeared to be mediated through beneficial effects on body weight, blood pressure, serum cholesterol, and glucose tolerance. Apart from its favorable influences on these variables, physical activity had no significant residual association with stroke incidence.

Type of alcoholic beverage and risk of myocardial infarction

We examined the relation of alcoholic beverage type and risk of myocardial infarction (MI) in a case-control study among 340 cases of MI and an equal number of age-, sex-, and community-matched controls. Alcohol consumption was estimated using a food frequency questionnaire, with alcohol drinkers defined as those consuming > or = 1/2 drink/day on average of any alcoholic beverage. Beer, wine, and liquor drinkers had at least half of their consumption from 1 beverage type. Fasting venous blood samples were obtained and analyzed for lipid profiles. Compared with nondrinkers, after adjustment for age and sex, reductions in risk of MI were similar for regular drinkers of any type of alcoholic beverage (relative risk [RR] 0.54; 95% confidence interval [CI] 0.37 to 0.79; p = 0.001), beer (RR 0.55; 95% CI 0.31 to 0.97; p <0.05), wine (RR 0.48; 95% CI 0.27 to 0.87; p <0.05), and liquor (RR 0.59; 95% CI 0.38 to 0.91; p <0.05) drinkers. Comparable benefits remained apparent even after multivariate adjustment for a wide range of nonlipid coronary risk factors. High-density lipoprotein (HDL) levels were significantly higher in all 4 beverage categories when compared with levels in nondrinkers, and as expected, adjustment for total HDL, a major direct effect of alcohol, substantially attenuated the protective effect in all 4 beverage categories. Relative risks were 0.94 for any beverage, 1.09 for beer, 0.97 for wine, and 0.83 for liquor after further adjustment. This strongly suggests that the protective effect of each beverage type is, in large part, mediated by increased HDL. These data indicate that regular consumption of small to moderate amounts of alcoholic beverages, regardless of the type, reduces the risk of MI, and further suggest that there is benefit, in large part, from increases in HDL levels.

Cancer occurrence in the elderly: agreement between three major data sources

PURPOSE

To explore agreement on cancer occurrence and site among Medicare Part A, Massachusetts Cancer Registry, and death certificates.

METHODS

We linked these data sources with the cohort of the population-based East Boston Senior Health Project, a component of the National Institute on Aging's Established Populations for Epidemiologic Studies of the Elderly. The cohort consists of 905 subjects dying between January 1986 and December 1990.

RESULTS

We detected the following agreements on cancer occurrence: hospitalization data and death certificates (kappa = 0.70), hospitalization and cancer registry data (kappa = 0.59), and cancer registry and death certificate data (kappa = 0.50). Measures of agreement changed little when the analyses were stratified by age, sex, calendar year and place of death, autopsy performance, cigarette smoking or alcohol consumption. Site-specific agreements were higher for colorectal and respiratory tract cancer compared to breast and prostate across all three comparisons.

CONCLUSIONS

The results should assist epidemiologists to better understand the strengths and limitations of these data sources.

Prospective study of herpes simplex virus, cytomegalovirus, and the risk of future myocardial infarction and stroke

BACKGROUND

It has been hypothesized that infection with either herpes simplex virus (HSV) or cytomegalovirus (CMV) is associated with atherogenesis. However, prospective data relating evidence of prior exposure to these agents with risks of future myocardial infarction (MI) and stroke are sparse.

METHODS AND RESULTS

In a prospective, nested case-control study of apparently healthy men, the baseline prevalence of antibodies directed against HSV or CMV was similar among 643 men who subsequently developed a first MI or thromboembolic stroke and among 643 age- and smoking-matched men who remained free of reported vascular disease over a 12-year follow-up period. Specifically, the relative risks for future MI and stroke were 0.94 (95% CI, 0.7 to 1.2) for HSV seropositivity and 0.72 (95% CI, 0.6 to 0.9) for CMV seropositivity, after adjustment for other cardiovascular risk factors. These findings were not materially altered in comparisons of early versus late events or in analyses stratified by smoking status. There was no evidence of association between HSV or CMV antibodies and plasma concentration of C-reactive protein, a marker of inflammation that predicts vascular risk in this cohort.

CONCLUSIONS

Among apparently healthy middle-aged men, IgG antibodies directed against HSV or CMV do not appear to be a marker for increased atherothrombotic risk. The observed possible inverse relationship of CMV with MI and stroke was unexpected and may well be due to chance, because the direction of association is not compatible with the a priori hypothesis based on proposed biological mechanisms or previous cross-sectional and retrospective data.

Mortality and light to moderate alcohol consumption after myocardial infarction

BACKGROUND

Although heavy alcohol consumption increases total mortality, light to moderate consumption decreases cardiovascular and all-cause mortality in apparently healthy people. Since data are sparse on the relation of light to moderate alcohol intake to mortality in patients with previous myocardial infarction, we did a prospective study of mortality in men.

METHOD

Of 90,150 men in the Physicians' Health Study enrollment cohort who provided information on alcohol intake and who had no history of cancer, stroke, or liver disease, 5358 had a previous myocardial infarction. We estimated alcohol consumption by food-frequency questionnaire.

FINDINGS

During a mean follow-up of 5 years, 920 men died. After adjustment for several potential confounders, moderate alcohol intake was associated with a significant decrease in total mortality (p=0.016). Compared with men who rarely or never drank alcohol, those who drank one to four drinks per month had a relative risk for total mortality of 0.85 (95% CI 0.69-1.05); for two to four drinks per week, the relative risk was 0.72 (0.58-0.89); for one drink per day 0.79 (0.64-9.96); and for two or more drinks per day 0.84 (0.55-1.26).

INTERPRETATION

Men with previous myocardial infarction who consume small to moderate amounts of alcohol have a lower total mortality.

Abdominal adiposity and coronary heart disease in women

CONTEXT

Obesity is a well-established risk factor for coronary heart disease (CHD), but whether regional fat distribution contributes independently to risk remains unclear.

OBJECTIVE

To compare waist-hip ratio (WHR) and waist circumference in determining risk of CHD in women.

DESIGN AND SETTING

Prospective cohort study among US female registered nurses participating in the Nurses' Health Study conducted between 1986, when the nurses completed a questionnaire, and follow-up in June 1994.

PARTICIPANTS

A total of 44702 women aged 40 to 65 years who provided waist and hip circumferences and were free of prior CHD, stroke, or cancer in 1986.

MAIN OUTCOME MEASURES

Incidence of CHD (nonfatal myocardial infarction or CHD death).

RESULTS

During 8 years of follow-up 320 CHD events (251 myocardial infarctions and 69 CHD deaths) were documented. Higher WHR and greater waist circumference were independently associated with a significantly increased age-adjusted risk of CHD. After adjusting for body mass index (BMI) (defined as weight in kilograms divided by the square of height in meters) and other cardiac risk factors, women with a WHR of 0.88 or higher had a relative risk (RR) of 3.25 (95% confidence interval [CI], 1.78-5.95) for CHD compared with women with a WHR of less than 0.72. A waist circumference of 96.5 cm (38 in) or more was associated with an RR of 3.06 (95% CI, 1.54-6.10). The WHR and waist circumference were independently strongly associated with increased risk of CHD also among women with a BMI of 25 kg/m2 or less. After adjustment for reported hypertension, diabetes, and high cholesterol level, a WHR of 0.76 or higher or waist circumference of 76.2 cm (30 in) or more was associated with more than a 2-fold higher risk of CHD.

CONCLUSIONS

The WHR and waist circumference are independently associated with risk of CHD in women.

Debrisoquine hydroxylase (CYP2D6) and prostate cancer

The p450 hepatic microsomal enzyme system metabolizes exogenous drugs and carcinogens. Debrisoquine hydroxylase (CYP2D6), one member of the p450 hemoproteins, has polymorphic expression leading to poor metabolism of debrisoquine and similar compounds in approximately 7% of Caucasians. The genetic locus for this enzyme has been characterized, and the mutations responsible for the slowed metabolism have been identified. Epidemiological studies of the CYP2D6 phenotype suggest an association between the normal or rapid metabolism phenotype and increased risk of lung and bladder cancer. Preliminary data have also suggested an association with prostate cancer (CaP). We used a PCR-based assay to investigate possible associations between the CYP2D6 B allele, the most common genetic mutation responsible for the poor metabolism phenotype, and CaP. Using genomic DNA isolated from peripheral blood, we genetically typed 571 men with CaP and 767 matched controls, all participants in the Physician's Health Study. Relative to men homozygous for the wild-type allele, heterozygotes for the B allele have an odds ratio of 1.19 (95% confidence interval, 0.94-1.51) for CaP, and men homozygous for the B allele have an odds ratio of 1.37 (95% confidence interval, 0.86-2.20). When analyzed as a trend over zero, one, or two copies of the B allele, there emerges a possible association between the B allele and an increased risk of CaP of borderline statistical significance (P = 0.07).

Frequent nut consumption and risk of coronary heart disease in women: prospective cohort study

OBJECTIVE

To examine the relation between nut consumption and risk of coronary heart disease in a cohort of women from the Nurses' Health Study.

DESIGN

Prospective cohort study.

SETTING

Nurses' Health Study.

SUBJECTS

86 016 women from 34 to 59 years of age without previously diagnosed coronary heart disease, stroke, or cancer at baseline in 1980.

MAIN OUTCOME MEASURES

Major coronary heart disease including non-fatal myocardial infarction and fatal coronary heart disease.

RESULTS

1255 major coronary disease events (861 cases of non-fatal myocardial infarction and 394 cases of fatal coronary heart disease) occurred during 14 years of follow up. After adjusting for age, smoking, and other known risk factors for coronary heart disease, women who ate more than five units of nuts (one unit equivalent to 1 oz of nuts) a week (frequent consumption) had a significantly lower risk of total coronary heart disease (relative risk 0.65, 95% confidence interval 0.47 to 0.89, P for trend=0.0009) than women who never ate nuts or who ate less than one unit a month (rare consumption). The magnitude of risk reduction was similar for both fatal coronary heart disease (0.61, 0.35 to 1.05, P for trend=0.007) and non-fatal myocardial infarction (0.68, 0.47 to 1.00, P for trend=0.04). Further adjustment for intakes of dietary fats, fibre, vegetables, and fruits did not alter these results. The inverse association persisted in subgroups stratified by levels of smoking,use of alcohol, use of multivitamin and vitamin E supplements, body mass index, exercise, and intake of vegetables or fruits.

CONCLUSIONS

Frequent nut consumption was associated with a reduced risk of both fatal coronary heart disease and non-fatal myocardial infarction. These data, and those from other epidemiological and clinical studies, support a role for nuts in reducing the risk of coronary heart disease.

Calcium channel blockers, cancer incidence, and cancer mortality in a cohort of U.S. women: the nurses' health study

BACKGROUND

Some studies have suggested that the use of calcium channel blockers may increase the risk of cancer. A possible association of the use of calcium channel blockers with cancer incidence and cancer mortality was addressed using data from the Nurses' Health Study.

METHODS

In this study, a total of 18,635 female nurses reported regularly taking at least 1 of 4 cardiovascular medications in 1988: diuretics, beta-blockers, calcium channel blockers, and/or angiotensin-converting enzyme (ACE) inhibitors. Cancer incidence and cancer deaths were ascertained until 1994.

RESULTS

During 6 years of follow-up, 852 women were newly diagnosed with cancer and 335 women died of cancer. Women who reported the use of calcium channel blockers had no increased risk of newly diagnosed cancer compared with those taking other cardiovascular drugs (relative risk=1.02; 95% CI 0.83-1.26). The relative risk of dying from cancer associated with the self-reported use of calcium channel blockers was 1.25 (95% CI 0.91-1.72). Relative risks were adjusted for the following self-reported factors: age; weight; height; cholesterol level; systolic and diastolic blood pressure; smoking; alcohol intake; physical activity; menopausal status; postmenopausal hormone use; aspirin use; and history of diabetes, cancer, stroke, myocardial infarction, coronary artery bypass graft or percutaneous transluminal coronary angioplasty, angina, and hypertension. Regarding site specific cancer incidence and mortality, only lung cancer incidence was somewhat increased (RR=1.61; 95% CI 0.88-2.96).

CONCLUSIONS

These data suggest no important increase in overall cancer incidence or cancer mortality related to the self-reported use of calcium channel blockers.

Glutathione S-transferase GSTM1 and GSTT1 polymorphisms and colorectal cancer risk: a prospective study

Glutathione S-transferase (GST) M1 and T1 genes encode GST enzymes, and are polymorphic in humans. These enzymes catalyze conjugation with glutathione, which is an important step in the detoxification of certain carcinogens. Several case-control studies have found associations of the homozygous null deletions in GSTM1 and GSTT1 with increasing the risk of colorectal and lung cancer. We prospectively examined the associations of the GSTM1 and GSTT1 polymorphisms with colorectal cancer risk in a nested case-control study (212 cases of colorectal cancer and 221 controls) within the Physicians' Health Study. Among controls, the prevalence of the GSTM1 homozygous null genotype was 53% and for GSTT1 homozygous null genotype, 23%. We found no increase in the risk of colorectal cancer for either GSTM1 null [odds ratio (OR) = 1.0; 95% confidence interval (CI), 0.7-1.5] or GSTT1 null (OR = 0.8; 95% CI, 0.5-1.2) genotypes. No differences were seen by site of colon cancer (proximal versus distal) or by age (< or = 60 years versus > 60 years). Current cigarette smokers with GSTM1 null genotype were not at an increased risk of colon cancer (OR = 1.2; 95% CI, 0.3-4.2) compared with current smokers without the null genotype; for the GSTT1 null genotype this OR was 1.1 = 95% CI (0.3-4.7). This lack of association persisted when we examined pack-years of smoking and age at starting smoking. Our results do not support an association of GSTM1 or GSTT1 polymorphisms with colorectal cancer or an interaction with cigarette smoking.

Low-dose aspirin and risk of cataract and subtypes in a randomized trial of U.S. physicians

PURPOSE

To examine whether low-dose aspirin (325 mg on alternate days) reduces the risk of age-related cataract and subtypes. This report extends previous findings, including both subtypes and additional newly identified incident cases since the earlier report.

METHODS

All 20,979 participants in the Physicians' Health Study, a randomized trial of aspirin and beta-carotene among U.S. male physicians age 40-84 in 1982, who did not report cataract at baseline were included. Average follow-up was five years. The main outcome measure was incident, age-related cataract responsible for a reduction in best-corrected visual acuity to 20/30 or worse, based on self-report confirmed by medical record review.

RESULTS

501 age-related cataracts were diagnosed during follow-up, including 416 with nuclear sclerosis and 212 with a posterior subcapsular component; 318 cataracts progressed to surgical extraction. Overall, there were 245 cataracts in the aspirin group and 256 in the placebo group (relative risk [RR], 0.94; 95% confidence interval [CI], 0.79 to 1.13; P = 0.52). Cataract extractions were 19% less frequent in the aspirin than in the placebo group (RR, 0.81; 95% CI, 0.65 to 1.01; P = 0.06). In subgroup analyses of subtypes, aspirin takers had a lower risk of posterior subcapsular cataract (RR, 0.74; 95% CI, 0.57 to 0.98; P = 0.03) but not nuclear sclerosis (RR, 0.96; 95% CI, 0.79 to 1.16; P = 0.65) cataract.

CONCLUSIONS

Overall, these randomized trial data tend to exclude a large benefit of five years of low-dose aspirin therapy on cataract development and extraction. The data are compatible with a modest benefit on cataract extraction for this duration of aspirin therapy. Subgroup analyses raise the possibility of a modest, but potentially important, protective effect of aspirin on posterior subcapsular cataract, a particularly disabling subtype.

Angiotensinogen genotype, sodium reduction, weight loss, and prevention of hypertension: trials of hypertension prevention, phase II

The angiotensinogen gene has been linked to essential hypertension and increased blood pressure. A functional variant believed to be responsible for hypertension susceptibility occurs at position -6 in the promoter region of the gene in which an A for G base pair substitution is associated with higher angiotensinogen levels. To test whether an allele within the angiotensinogen gene is related to subsequent incidence of hypertension and blood pressure response to sustained sodium reduction, 1509 white male and female subjects participating in phase II of the Trials of Hypertension Prevention were genotyped at the angiotensinogen locus. Participants had diastolic blood pressures between 83 and 89 mm Hg and were randomized in a 2x2 factorial design to sodium reduction, weight loss, combined intervention, or usual care groups. Persons in the usual care group with the AA genotype at nucleotide position -6 had a higher 3-year incidence rate of hypertension (44.6%) compared with those with the GG genotype (31.5%), with a relative risk of 1.4 (95% confidence interval [0.87, 2.34], test for trend across all 3 genotypes, P=0.10). In contrast, the incidence of hypertension was significantly lower after sodium reduction for persons with the AA genotype (relative risk=0.57 [0.34, 0.98] versus usual care) but not for persons with the GG genotype (relative risk=1.2 [0.79, 1.81], test for trend P=0.02). Decreases of diastolic blood pressure at 36 months in the sodium reduction group versus usual care showed a significant trend across all 3 genotypes (P=0.01), with greater net blood pressure reduction in those with the AA genotype (-2.2 mm Hg) than those with the GG genotype (+1.1 mm Hg). A similar trend across the 3 genotypes for net systolic blood pressure reduction (-2.7 for AA versus -0.2 mm Hg for GG) was not significant (P=0.17). Trends across genotypes for the effects of weight loss on hypertension incidence and decreases in blood pressure were similar to those for sodium reduction. We conclude that the angiotensinogen genotype may affect blood pressure response to sodium or weight reduction and the development of hypertension.

Prospective study of C-reactive protein and the risk of future cardiovascular events among apparently healthy women

BACKGROUND

C-reactive protein (CRP) predicts risk of myocardial infarction (MI) and stroke among apparently healthy men, but in women, virtually no data are available.

METHODS AND RESULTS

CRP was measured in baseline blood samples from 122 apparently healthy participants in the Women's Health Study who subsequently suffered a first cardiovascular event and from 244 age- and smoking-matched control subjects who remained free of cardiovascular disease during a 3-year follow-up period. Women who developed cardiovascular events had higher baseline CRP levels than control subjects (P=0.0001), such that those with the highest levels at baseline had a 5-fold increase in risk of any vascular event (RR=4.8; 95% CI, 2.3 to 10.1; P=0.0001) and a 7-fold increase in risk of MI or stroke (RR=7.3; 95% CI, 2.7 to 19.9; P=0.0001). Risk estimates were independent of other risk factors, and prediction models that included CRP provided a better method to predict risk than models that excluded CRP (all P values <0.01). In stratified analyses, CRP was a predictor among subgroups of women with low as well as high risk as defined by other cardiovascular risk factors.

CONCLUSIONS

In these prospective data among women, CRP is a strong independent risk factor for cardiovascular disease that adds to the predictive value of risk models based on usual factors alone. (Circulation. 1998;98:731-733.)

A prospective study of N-acetyltransferase genotype, red meat intake, and risk of colorectal cancer

Carcinogenic heterocyclic amines are activated by N-acetyltransferase (NAT) enzymes, encoded by NAT1 and NAT2, to genotoxic compounds that can form DNA adducts in the colon epithelium. We have examined the relation of polymorphisms in the genes coding for both enzymes to risk of colorectal cancer and the gene-environment interaction with red meat intake among participants in the prospective Physicians' Health Study. Baseline blood samples from 212 men subsequently diagnosed with colorectal cancer during 13 years of follow-up were genotyped, along with 221 controls. NAT genotypes were analyzed by a PCR-restriction fragment length polymorphism method. Effect modification of the relation of red meat intake and risk of colorectal cancer by NAT genotype was assessed using conditional logistic regression. There was no overall independent association of NAT acetylation genotypes and colorectal cancer risk. The relative risks for the rapid acetylation genotype were 0.93 [95% confidence interval (CI), 0.61-1.42] for NAT1, 0.80 (95% CI, 0.53-1.19) for NAT2, and 0.81 (95% CI, 0.52-1.27) for NAT1/NAT2 combined. We observed a stronger association of red meat intake with cancer risk among NAT rapid acetylators, especially among men 60 years old or older. Among those men who were rapid acetylators for both NAT1 and NAT2, consumption of >1 serving of red meat per day was associated with a relative risk of 5.82 (95% CI, 1.11-30.6) compared with consumption of < or = 0.5 serving per day (P, trend = 0.02). These prospective data, which need to be confirmed in other studies, suggest that polymorphisms in the NAT genes confer differential susceptibility to the effect of red meat consumption on colorectal cancer risk.

Lipoprotein (a), lipids, aspirin, and risk of myocardial infarction in the Physician's Health Study

BACKGROUND

Previously reported data from the Physicians' Health Study indicate that there is no association between lipoprotein (a) level and subsequent risk of myocardial infarction among members of a large cohort of middle-aged men followed up prospectively for an average of 60.2 months.

OBJECTIVE

To investigate whether this null finding is related to the generally favorable lipid profile of the cohort or to randomized assignment of aspirin.

METHODS

In a follow-up analysis of 296 confirmed cases of myocardial infarction and 296 controls, we evaluated the association between lipoprotein (a) level and cardiovascular risk for those with and without hyperlipidemia as well as for those randomly allocated aspirin treatment and placebo.

RESULTS

For those with total cholesterol levels > or = 200 mg/dl, the age-adjusted smoking-adjusted relative risks of a first myocardial infarction associated with lipoprotein (a) levels above the 25th, 50th, 75th, 90th, and 95th percentiles of the control distribution were 0.9, 1.1, 1.6, 1.7 and 1.0 (all NS; P for trend 0.5). Among those with total cholesterol levels < 200 mg/dl, the adjusted relative risks of myocardial infarction associated with these cutoff points were 0.9, 0.7, 1.2, 0.7, and 1.4 (all NS; P for trend 0.7). Analyses limited to those with total cholesterol levels > or = 240 mg/dl or to men with higher than normal total cholesterol: high-density lipoprotein ratios revealed similar null findings. We observed no significant interaction between total cholesterol and lipoprotein (a) levels for these groups. For those randomly allocated aspirin, the age-adjusted and smoking-adjusted relative risks of myocardial infarction associated with lipoprotein (a) levels above the 25th, 50th, 75th, 90th, and 95th percentile cutoff points were 0.9, 0.9, 1.5, 1.5, and 1.0 (all NS; P trend 0.9). For those randomly allocated placebo, the age-adjusted and smoking-adjusted relative risks of myocardial infarction associated with lipoprotein (a) levels were 0.8, 0.9, 1.4, 1.5, and 1.3 (all NS; P trend 0.9). There was no significant interaction between aspirin and lipoprotein (a) level for any of these groups. Similar null findings were observed in analyses evaluating evidence for there being a trend across increasing quartiles of lipoprotein (a).

CONCLUSION

These prospective data indicate that neither levels of lipids nor aspirin treatment modified the lack of overall effect of lipoprotein (a) on the risk of a first myocardial infarction in the Physicians' Health Study.

Beta-carotene-induced enhancement of natural killer cell activity in elderly men: an investigation of the role of cytokines

We showed previously that natural killer (NK) cell activity is significantly greater in elderly men supplemented with beta-carotene than in those taking placebo. In an attempt to determine the mechanism of beta-carotene's effect, we analyzed the production of NK cell-enhancing cytokines (interferon alpha, interferon gamma, and interleukin 12). Boston-area participants in the Physicians' Health Study (men aged 65-88 y; mean age, 73 y) who had been supplemented with beta-carotene (50 mg on alternate days) for an average of 12 y were enrolled in a randomized, placebo-controlled, double-blind study. Elderly subjects taking beta-carotene supplements had significantly greater plasma beta-carotene concentrations than those taking placebo. Beta-carotene-supplemented elderly men had significantly greater NK cell activity than did elderly men receiving placebo. Percentages of NK cells (CD16+CD56+) were not significantly different between the beta-carotene and placebo groups. Production of interleukin 12, interferon alpha, or concanavalin A-stimulated interferon gamma by cultured peripheral blood mononuclear cells was not significantly different between beta-carotene-supplemented elderly and those taking placebo. Our results indicate that beta-carotene-induced enhancement of NK cell activity is not mediated by changes in percentages of CD16+CD56+ NK cells nor through up-regulation of interleukin 12 or interferon alpha.

Lessons from hypertension trials

Hypertension is a well-established risk factor for stroke, myocardial infarction (MI), and premature cardiovascular death. Even mild elevations of blood pressure (i.e., diastolic blood pressure >90 and <110 mm Hg) yield increased risk. In fact, mild-to-moderate hypertension is more common than severe hypertension and accounts for a greater proportion of the deaths and serious nonfatal vascular events. The treatment goal is to make optimal use of antihypertensive drug therapy while encouraging patients to implement lifestyle changes such as weight loss, sodium restriction, decreased alcohol intake, and increased exercise. Pharmacologic therapy of mild-to-moderate hypertension can significantly reduce the incidence of stroke, MI, coronary artery disease, vascular mortality, and total mortality. Beta blockers and diuretics should continue to be used as first-line therapy until there is direct and reliable evidence from large-scale randomized trials with clinical endpoints for newer agents such as calcium antagonists and angiotensin-converting enzyme inhibitors.