Moderate alcohol consumption and the risk of sudden cardiac death among US male physicians

BACKGROUND

Individuals who consume high amounts of alcohol (>5 drinks/d) have increased risks of ventricular arrhythmia and sudden cardiac death (SCD). However, the relationship is less clear for drinkers of light-to-moderate amounts.

METHODS AND RESULTS

We prospectively assessed whether light-to-moderate alcohol drinkers have a decreased risk of SCD among 21 537 male participants in the Physicians Health Study who were free of self-reported cardiovascular disease and provided complete information on alcohol intake at study entry. Over 12 years of follow-up, 141 SCDs were confirmed. After control for multiple confounders, men who consumed 2 to 4 drinks/wk (RR=0.40; 95% CI, 0.22 to 0.75; P=0.004) or 5 to 6 drinks/wk (RR=0.21; 95% CI, 0.08 to 0.56; P=0.002) at baseline had significantly reduced risks of SCD compared with those who rarely or never consumed alcohol. The relationship for SCD was U-shaped (P=0. 002), with the risk approaching unity at >/=2 drinks/d. In contrast, the relationship of alcohol intake and nonsudden CHD death was L-shaped or linear (P for trend=0.02).

CONCLUSIONS

In these prospective data, men who consumed light-to-moderate amounts of alcohol (2 to 6 drinks/wk) had a significantly reduced risk of SCD compared with those who rarely or never consumed alcohol.

A prospective study of walking as compared with vigorous exercise in the prevention of coronary heart disease in women

BACKGROUND

The role of walking, as compared with vigorous exercise, in the prevention of coronary heart disease remains controversial, and data for women on this topic are sparse.

METHODS

We prospectively examined the associations between the score for total physical activity, walking, and vigorous exercise and the incidence of coronary events among 72,488 female nurses who were 40 to 65 years old in 1986. Participants were free of diagnosed cardiovascular disease or cancer at the time of entry and completed serial detailed questionnaires about physical activity. During eight years of follow-up, we documented 645 incident coronary events (nonfatal myocardial infarction or death from coronary disease).

RESULTS

There was a strong, graded inverse association between physical activity and the risk of coronary events. As compared with women in the lowest quintile group for energy expenditure (expressed as the metabolic-equivalent [MET] score), women in increasing quintile groups had age-adjusted relative risks of 0.77, 0.65, 0.54, and 0.46 for coronary events (P for trend <0.001). In multivariate analyses, the inverse gradient remained strong (relative risks, 0.88, 0.81, 0.74, and 0.66 for women in increasing quintile groups as compared with those in the lowest quintile group; P for trend=0.002). Walking was inversely associated with the risk of coronary events; women in the highest quintile group for walking, who walked the equivalent of three or more hours per week at a brisk pace, had a multivariate relative risk of 0.65 (95 percent confidence interval, 0.47 to 0.91) as compared with women who walked infrequently. Regular vigorous exercise (> or =6 MET) was associated with similar risk reductions (30 to 40 percent). Sedentary women who became active in middle adulthood or later had a lower risk of coronary events than their counterparts who remained sedentary.

CONCLUSIONS

These prospective data indicate that brisk walking and vigorous exercise are associated with substantial and similar reductions in the incidence of coronary events among women.

Hormone replacement therapy and increased plasma concentration of C-reactive protein

BACKGROUND

It has been hypothesized that postmenopausal hormone replacement therapy (HRT) may increase levels of C-reactive protein (CRP), a marker of inflammation associated with increased risk of future cardiovascular events. However, data evaluating this hypothesis are sparse and limited to older women.

METHODS AND RESULTS

CRP levels were evaluated in a cross-sectional survey of 493 healthy postmenopausal women; mean age was 51 years. Overall, median CRP levels were 2 times higher among women taking HRT than among women not taking HRT (0.27 versus 0.14 mg/dL; P=0.001). This difference was present in all subgroups evaluated, including those with no history of hypertension, hyperlipidemia, obesity, diabetes, or cigarette consumption or a family history of premature coronary artery disease (all P< 0.01). Compared with nonusers of HRT, median CRP levels were higher among women using estrogen alone (P=0.003) and women using estrogen plus progesterone (P=0.03); however, there was no significant difference in CRP levels between users of different HRT preparations. In multivariate analysis, the relationship between HRT use and CRP remained significant after control for body mass index, age, diabetes, hypertension, hyperlipidemia, alcohol use, and cigarette consumption (P=0.001).

CONCLUSIONS

In this cross-sectional survey, CRP levels were increased among apparently healthy postmenopausal women taking HRT. The potential impact of HRT on inflammatory parameters should be investigated in ongoing clinical trials.

Dietary protein and risk of ischemic heart disease in women

BACKGROUND

Ingestion of animal protein raises serum cholesterol in some experimental models but not in others, and ecologic studies have suggested a positive association between animal protein intake and risk of ischemic heart disease. Prospective data on the relation of protein intake to risk of ischemic heart disease are sparse.

OBJECTIVE

The objective was to examine the relation between protein intake and risk of ischemic heart disease.

DESIGN

The study was a prospective cohort study.

RESULTS

We examined the association between dietary protein intake and incidence of ischemic heart disease in a cohort of 80082 women aged 34-59 y and without a previous diagnosis of ischemic heart disease, stroke, cancer, hypercholesterolemia, or diabetes in 1980. Intakes of protein and other nutrients were assessed with validated dietary questionnaires. We documented 939 major instances of ischemic heart disease during 14 y of follow-up. After age, smoking, total energy intake, percentages of energy from specific types of fat, and other ischemic heart disease risk factors were controlled for, high protein intakes were associated with a low risk of ischemic heart disease; when extreme quintiles of total protein intake were compared, the relative risk was 0.74 (95% CI: 0.59, 0.94). Both animal and vegetable proteins contributed to the lower risk. This inverse association was similar in women with low- or high-fat diets.

CONCLUSIONS

Our data do not support the hypothesis that a high protein intake increases the risk of ischemic heart disease. In contrast, our findings suggest that replacing carbohydrates with protein may be associated with a lower risk of ischemic heart disease. Because a high dietary protein intake is often accompanied by increases in saturated fat and cholesterol intakes, application of these findings to public dietary advice should be cautious.

Misclassification and under-reporting of acute myocardial infarction by elderly persons: implications for community-based observational studies and clinical trials

We investigated the accuracy of self-report of hospitalization for acute myocardial infarction (MI) by elderly persons in a community-based prospective study. Among 3809 persons aged 65 years or older followed up for 6 years, self-reported hospitalization for MI was validated by review of primary records and Medicare diagnoses. Among 147 who self-reported MI and for whom hospital records were available, the diagnosis was confirmed in 79 (54%). Myocardial infarction was not a reason for hospitalization among the remaining 68 participants; misclassification with other cardiovascular diagnoses was common. Medicare diagnosis correlated well with primary hospital records. Using Medicare diagnoses as the standard, the diagnosis of MI was confirmed in 53% of self-reports; the sensitivity and specificity of self-report were 51% and 98%, respectively. False-negative reporting was common because only half of hospitalizations for MI were reported. Self-report of hospitalization for MI by elderly persons in the community may be unreliable for ascertaining trends in cardiovascular diseases.

Cross-sectional study of soluble intercellular adhesion molecule-1 and cardiovascular risk factors in apparently healthy men

An elevated plasma concentration of the soluble intercellular adhesion molecule-1 (sICAM-1) is associated with increased risk for future coronary events. However, data exploring the interrelations of sICAM-1 with known cardiovascular risk factors are sparse. We determined sICAM-1 levels in 948 middle-aged men with no prior history of cardiovascular disease. sICAM-1 levels increased with age (P<0.001) and were significantly associated with smoking (P<0.001), hypertension (P<0.05), and frequent alcohol consumption (P=0.006). Positive correlations were observed between sICAM-1 and triglycerides (r=0.15; P<0.001), fibrinogen (r=0.21; P<0.001), tissue-type plasminogen activator antigen (r=0.17; P<0.001), and total homocysteine (r=0.09; P=0.02); whereas a negative correlation was observed for high density lipoprotein cholesterol (r=-0.15; P<0. 001). Overall, plasma concentrations of sICAM-1 increased with increasing prevalence of usual cardiovascular risk factors; mean plasma concentrations were 231, 236, 245, 257, and 312 ng/mL for those subjects with 0, 1, 2, 3, and >4 risk factors, respectively (P<0.01 for trend). In multivariate analysis, age, smoking status, diabetes, systolic blood pressure, positive family history of coronary disease, and serum levels of total homocysteine and fibrinogen were all independently associated with sICAM-1 levels (all P</=0.05). sICAM-1 levels are associated with several established cardiovascular risk factors. Further studies will be needed to evaluate whether these associations reflect the role of sICAM-1 as a marker of preclinical atherosclerosis, and whether such interrelations might have a causal basis.

Determinants of retinopathy progression in type 1 diabetes mellitus

PURPOSE

To determine the risk factors for retinopathy progression in type 1 (insulin-dependent) diabetes mellitus in a prospective cohort study.

SUBJECTS AND METHODS

Subjects were 485 participants in the Sorbinil Retinopathy Trial, a randomized trial of aldose reductase inhibition among patients aged 18 to 56 years with type 1 diabetes mellitus (duration of 1 to 15 years) and no or only mild retinopathy. Retinopathy progression, assessed by seven-field stereoscopic fundus photography, was defined as worsening by two or more levels on a standardized grading scale at the end of follow-up (median, 41 months).

RESULTS

The relative risks for retinopathy progression according to successively greater quintiles of total glycosylated hemoglobin level at baseline, after adjusting for age, diabetes duration, sorbinil assignment, and other variables, were 1.0, 2.0, 1.6, 3.7, and 4.4 (P trend <0.0001). Risk increased with greater baseline diastolic blood pressure: 1.0 for <70 mm Hg, 1.2 for 70 to 79 mm Hg, and 1.8 for > or =80 mm Hg (P for trend = 0.04). Diastolic blood pressure was a significant risk factor for progression in participants with mild baseline retinopathy (P for trend <0.02) but not in those without retinopathy at entry. Systolic blood pressure, by comparison, was not associated with progression. Baseline total cholesterol level was a marginally significant predictor of retinopathy progression when examined as a categorical variable (relative risks for increasing quartiles; 1.0, 1.6, 1.8, 1.9; P for trend = 0.03) but not when it was examined as a continuous variable or when hypercholesterolemic patients were compared with those with normal levels. Furthermore, when cholesterol levels were updated in subsequent visits, it was not a significant predictor of progression, and low density lipoprotein (LDL) cholesterol levels did not predict progression no matter how analyzed. Smoking was not associated with progression of retinopathy.

CONCLUSIONS

Levels of hyperglycemia and diastolic blood pressure predicted progression of retinopathy in type 1 diabetes mellitus. We found only a suggestion of an association between total cholesterol level (but not of LDL cholesterol level) and progression of retinopathy; resolution of this issue will require additional studies with larger sample sizes and longer follow-up.

Long-term intake of dietary fiber and decreased risk of coronary heart disease among women

CONTEXT

Epidemiological studies of men suggest that dietary fiber intake protects against coronary heart disease (CHD), but data on this association in women are sparse.

OBJECTIVE

To examine the association between long-term intake of total dietary fiber as well as fiber from different sources and risk of CHD in women.

DESIGN AND SETTING

The Nurses' Health Study, a large, prospective cohort study of US women followed up for 10 years from 1984. Dietary data were collected in 1984, 1986, and 1990, using a validated semiquantitative food frequency questionnaire.

PARTICIPANTS

A total of 68782 women aged 37 to 64 years without previously diagnosed angina, myocardial infarction (MI), stroke, cancer, hypercholesterolemia, or diabetes at baseline.

MAIN OUTCOME MEASURE

Incidence of acute MI or death due to CHD by amount of fiber intake.

RESULTS

Response rate averaged 80% to 90% during the 10-year follow-up. We documented 591 major CHD events (429 nonfatal MIs and 162 CHD deaths). The age-adjusted relative risk (RR) for major CHD events was 0.53 (95% confidence interval [CI], 0.40-0.69) for women in the highest quintile of total dietary fiber intake (median, 22.9 g/d) compared with women in the lowest quintile (median, 11.5 g/d). After controlling for age, cardiovascular risk factors, dietary factors, and multivitamin supplement use, the RR was 0.77 (95% CI, 0.57-1.04). For a 10-g/d increase in total fiber intake (the difference between the lowest and highest quintiles), the multivariate RR of total CHD events was 0.81 (95% CI, 0.66-0.99). Among different sources of dietary fiber (eg, cereal, vegetables, fruit), only cereal fiber was strongly associated with a reduced risk of CHD (multivariate RR, 0.63; 95% CI, 0.49-0.81 for each 5-g/d increase in cereal fiber).

CONCLUSIONS

Our findings in women support the hypothesis that higher fiber intake, particularly from cereal sources, reduces the risk of CHD.

Age at natural menopause and risk of cardiovascular disease

BACKGROUND

Early natural menopause has been postulated to increase the risk of cardiovascular disease.

OBJECTIVE

To examine the relation of age at natural menopause with risk of coronary heart disease (CHD) and stroke in the Nurses' Health Study.

METHODS

Analysis was restricted to 35 616 naturally postmenopausal women who never used estrogen replacement therapy and with no diagnosed cardiovascular disease at baseline, followed up from 1976 to 1994. Information on menopausal status, age at menopause, and other risk factors was obtained in 1976 and updated every 2 years by mailed questionnaires.

RESULTS

During 354326 person-years of follow-up, we documented 757 incident cases of CHD and 350 incident cases of stroke. After adjusting for age, smoking status, and other cardiovascular risk factors, the relative risks (RRs) across categories of age at natural menopause (<40, 40-44, 45-49, 50-54, and > or = 55 years) were 1.53, 1.42, 1.10, 1.00 (reference), and 0.95, respectively; the RR for each 1-year decrease in age at natural menopause was 1.03 (95% confidence interval, 1.01-1.05). Elevated risk with younger age at menopause was observed among current smokers (RR, 1.04 [95% CI, 1.01-1.07] for each 1-year decrease in age at natural menopause) but not among never smokers (RR, 1.00; 95% CI, 0.96-1.04). Age at natural menopause was not significantly associated with ischemic stroke (RR, 1.01; 95% CI, 0.97-1.04) or hemorrhagic stroke (RR, 1.03; 95% CI, 0.97-1.10).

CONCLUSIONS

We observed an overall significant association between younger age at menopause and higher risk of CHD among women who experienced natural menopause and never used hormone therapy. This increased risk was observed among current smokers but not among never smokers. The apparent elevated risk of CHD with decreased age at natural menopause among smokers might reflect residual confounding by smoking.

Homocysteine and risk of cardiovascular disease among postmenopausal women

CONTEXT

Individuals with elevated levels of homocysteine tend to have higher prevalence of cardiovascular disease. However, prospective studies of homocysteine are inconsistent and data among women are limited.

OBJECTIVE

To determine whether elevated homocysteine levels in healthy postmenopausal women predict risk of developing cardiovascular disease.

DESIGN

Prospective, nested case-control study with a mean 3-year follow-up.

SETTING

The Women's Health Study, an ongoing US primary prevention trial initiated in 1993.

PARTICIPANTS

From a total cohort of 28,263 postmenopausal women with no history of cardiovascular disease or cancer at baseline, 122 women who subsequently experienced cardiovascular events were defined as cases, and 244 age- and smoking status-matched women who remained free of disease during follow-up were defined as controls.

MAIN OUTCOME MEASURES

Incidence of death due to cardiovascular disease, nonfatal myocardial infarction (MI), stroke, percutaneous transluminal coronary angioplasty, or coronary artery bypass graft by baseline homocysteine level.

RESULTS

Of the 122 cases, there were 85 events of MI or stroke and 37 coronary revascularizations. Case subjects had significantly higher baseline homocysteine levels than controls (14.1 vs 12.4 micromol/L; P = .02). Subjects with homocysteine levels in the highest quartile had a 2-fold increase in risk of any cardiovascular event (relative risk [RR], 2.0; 95% confidence interval [CI], 1.1-3.8). This effect was largely due to an excess of cases with high levels of homocysteine; the RR for those with homocysteine levels at or higher than the 95th percentile (20.7 micromol/L) was 2.6 (95% CI, 1.1-5.7). Risk estimates were independent of traditional risk factors and were greatest for the end points of MI and stroke (RR for those with baseline homocysteine levels in the top quartile, 2.2; 95% CI, 1.1-4.6). Self-reported multivitamin supplement use at study entry was associated with significantly reduced levels of homocysteine (P<.001). However, the association between increasing quartile of homocysteine level and risk of MI or stroke remained significant in analyses controlling for baseline multivitamin supplement use (P = .003 for trend), and subgroup analyses limited to women who were (P = .02 for trend) or were not (P = .04 for trend) taking multivitamin supplements.

CONCLUSIONS

Among healthy postmenopausal US women, elevated levels of homocysteine moderately increased the risk of future cardiovascular disease. Whether lowering the homocysteine level reduces risk of cardiovascular events requires testing in randomized controlled trials.

The renal effects of nonsteroidal anti-inflammatory drugs in older people: findings from the Established Populations for Epidemiologic Studies of the Elderly

OBJECTIVE

To determine whether older people who use nonsteroidal anti-inflammatory agents (NSAIDs) have increased levels of blood urea nitrogen (BUN), serum creatinine, and BUN:serum creatinine ratio.

DESIGN

Cross-sectional, secondary data analysis.

SETTING

Older people living in the communities of East Boston, MA, New Haven, CT, and Washington and Iowa Counties, Iowa.

PARTICIPANTS

A total of 4099 people aged 70 years or older who were participants in the National Institute on Aging's Established Populations for Epidemiologic Studies of the Elderly project, had survived to the 6-year follow-up interview and had consented to the blood drawing.

MEASUREMENTS

We assessed use of the NSAIDs at the 3- and 6-year interviews through a drug inventory and visual review of medication containers. Markers of renal function assessed through analysis of blood samples drawn at the time of the interview included BUN and creatinine.

RESULTS

Fifteen percent of the cohort reported use of NSAIDs during the 2 weeks preceding the 6-year interview. Controlling for age, sex, and a range of potential confounding variables, NSAID users had significant prevalence odds ratios of 1.9 (95% confidence interval (CI), 1.5-2.3) for being in the highest quartile of BUN (>23), 1.3 (CI 1.1-1.7) for the highest quartile of serum creatinine (> or =1.4), and 1.7 (CI 1.4-2.1) for the highest quartile of the BUN:creatinine ratio (> or = 19.4). Chronic NSAID users (those who reported NSAID use at both the 3-year and 6-year interviews) accounted for the increased risk of high serum creatinine levels.

CONCLUSION

Community-dwelling older people who use NSAIDs tend to have higher levels of common laboratory markers of renal dysfunction. This hypothesis requires further testing in prospective cohort studies designed a priori to evaluate these issues.

CAG repeat within the androgen receptor gene and incidence of surgery for benign prostatic hyperplasia in U.S. physicians

BACKGROUND

CAG repeat length in exon 1 of the androgen receptor (AR) gene correlates inversely with transcriptional transactivation activity of the AR. Men with shorter AR CAG repeat lengths are at higher risk of prostate cancer. Because benign prostatic hyperplasia (BPH) is an androgen-dependent condition, we examined the hypothesis that a shorter AR gene CAG repeat length increases the risk of developing of BPH.

METHODS

Among 14,916 men of the Physicians' Health Study who had provided a blood sample in 1982, we measured AR gene CAG repeat lengths for 310 men who had surgery for BPH up to 7.5 years of follow-up and 1,041 controls.

RESULTS

Risk of surgery for BPH increased linearly with decreasing AR CAG repeat length (P (trend) = 0.03). Relative to men with a CAG repeat length > or = 25, men with a repeat length < or = 19 had an odds ratio of BPH surgery of 1.76 (95% confidence interval, 1.16-2.65).

CONCLUSIONS

Variability in the AR gene CAG repeat influences the development of symptomatic BPH.

Dietary intake of alpha-linolenic acid and risk of fatal ischemic heart disease among women

BACKGROUND

Experimental studies in laboratory animals and humans suggest that alpha-linolenic acid (18:3n-3) may reduce the risk of arrhythmia.

OBJECTIVE

The objective was to examine the association between dietary intake of alpha-linolenic acid and risk of fatal ischemic heart disease (IHD).

DESIGN

This was a prospective cohort study. The intake of alpha-linolenic acid was derived from a 116-item food-frequency questionnaire completed in 1984 by 76283 women without previously diagnosed cancer or cardiovascular disease.

RESULTS

During 10 y of follow-up, we documented 232 cases of fatal IHD and 597 cases of nonfatal myocardial infarction. After adjustment for age, standard coronary risk factors, and dietary intake of linoleic acid and other nutrients, a higher intake of alpha-linolenic acid was associated with a lower relative risk (RR) of fatal IHD; the RRs from the lowest to highest quintiles were 1.0, 0.99, 0.90, 0.67, and 0.55 (95% CI: 0.32, 0.94; P for trend = 0.01). For nonfatal myocardial infarction there was only a modest, nonsignificant trend toward a reduced risk when extreme quintiles were compared (RR: 0.85; 95% CI: 0.61, 1.19; P for trend = 0.50). A higher intake of oil and vinegar salad dressing, an important source of alpha-linolenic acid, was associated with reduced risk of fatal IHD when women who consumed this food > or =5-6 times/wk were compared with those who rarely consumed this food (RR: 0.46; 95% CI: 0.27, 0.76; P for trend = 0.001).

CONCLUSIONS

This study supports the hypothesis that a higher intake of alpha-linolenic acid is protective against fatal IHD. Higher consumption of foods such as oil-based salad dressing that provide polyunsaturated fats, including alpha-linolenic acid, may reduce the risk of fatal IHD.

A retrospective cohort study of cigarette smoking and risk of rheumatoid arthritis in female health professionals

OBJECTIVE

To study the association of cigarette smoking with risk of rheumatoid arthritis (RA), among 377,481 female health professionals in the Women's Health Cohort Study.

METHODS

Subjects completed mailed questionnaires regarding demographics, health habits, including cigarette smoking history, and medical history, including RA diagnosis made by a physician and date of diagnosis. Of 7,697 women who self-reported RA, 3,416 reported seropositive RA. Cox proportional hazards regression models were used to retrospectively assess the associations of smoking intensity and duration with the risk of developing RA or seropositive RA. Cigarette smoking status was treated as a time-varying exposure in these regression models.

RESULTS

In multivariate analyses controlling for age, race, education, age at menarche, pregnancy history, menopausal status, and postmenopausal hormone use, duration of smoking was associated with a significantly increased risk of both RA and seropositive RA (both P < 0.01 for trend), after adjusting for smoking intensity. Women who smoked > or =25 cigarettes/day for more than 20 years experienced a 39% increased risk of RA and 49% increased risk of seropositive RA. However, smoking intensity (number of cigarettes/day) was unrelated to risk of RA or seropositive RA (both P = 0.3 for trend), after adjusting for duration of smoking.

CONCLUSION

Duration, but not intensity, of cigarette smoking is associated with a modest increased risk of RA in women.

A prospective study of egg consumption and risk of cardiovascular disease in men and women

CONTEXT

Reduction in egg consumption has been widely recommended to lower blood cholesterol levels and prevent coronary heart disease (CHD). Epidemiologic studies on egg consumption and risk of CHD are sparse.

OBJECTIVE

To examine the association between egg consumption and risk of CHD and stroke in men and women.

DESIGN AND SETTING

Two prospective cohort studies, the Health Professionals Follow-up Study (1986-1994) and the Nurses' Health Study (1980-1994).

PARTICIPANTS

A total of 37851 men aged 40 to 75 years at study outset and 80082 women aged 34 to 59 years at study outset, free of cardiovascular disease, diabetes, hypercholesterolemia, or cancer.

MAIN OUTCOME MEASURES

Incident nonfatal myocardial infarction, fatal CHD, and stroke corresponding to daily egg consumption as determined by a food-frequency questionnaire.

RESULTS

We documented 866 incident cases of CHD and 258 incident cases of stroke in men during 8 years of follow-up and 939 incident cases of CHD and 563 incident cases of stroke in women during 14 years of follow-up. After adjustment for age, smoking, and other potential CHD risk factors, we found no evidence of an overall significant association between egg consumption and risk of CHD or stroke in either men or women. The relative risks (RRs) of CHD across categories of intake were less than 1 per week (1.0), 1 per week (1.06), 2 to 4 per week (1.12), 5 to 6 per week (0.90), and > or =1 per day (1.08) (P for trend = .75) for men; and less than 1 per week (1.0), 1 per week (0.82), 2 to 4 per week (0.99), 5 to 6 per week (0.95), and > or =1 per day (0.82) (P for trend = .95) for women. In subgroup analyses, higher egg consumption appeared to be associated with increased risk of CHD only among diabetic subjects (RR of CHD comparing more than 1 egg per day with less than 1 egg per week among diabetic men, 2.02 [95% confidence interval, 1.05-3.87; P for trend = .04], and among diabetic women, 1.49 [0.88-2.52; P for trend = .008]).

CONCLUSIONS

These findings suggest that consumption of up to 1 egg per day is unlikely to have substantial overall impact on the risk of CHD or stroke among healthy men and women. The apparent increased risk of CHD associated with higher egg consumption among diabetic participants warrants further research.

Prospective study of colorectal cancer risk in men and plasma levels of insulin-like growth factor (IGF)-I and IGF-binding protein-3

BACKGROUND

Insulin-like growth factor-I (IGF-I) is a potent mitogen for normal and neoplastic cells, whereas IGF-binding protein-3 (IGFBP-3) inhibits cell growth in many experimental systems. Acromegalics, who have abnormally high levels of growth hormone and IGF-I, have higher rates of colorectal cancer. We therefore examined associations of plasma levels of IGF-I and IGFBP-3 with the risk of colorectal cancer in a prospective case-control study nested in the Physicians' Health Study.

METHODS

Plasma samples were collected at baseline from 14916 men without diagnosed cancer. IGF-I, IGF-II, and IGFBP-3 were assayed among 193 men later diagnosed with colorectal cancer during 14 years of follow-up and among 318 age- and smoking-matched control subjects. All P values are two-sided.

RESULTS

IGFBP-3 levels correlated with IGF-I levels (r=.64) and with IGF-II levels (r=.90). After controlling for IGFBP-3, age, smoking, body mass index (weight in kg/[height in m]2), and alcohol intake, men in the highest quintile for IGF-I had an increased risk of colorectal cancer compared with men in the lowest quintile (relative risk [RR]=2.51; 95% confidence interval [CI]=1.15-5.46; P for trend = .02). After controlling for IGF-I and other covariates, men with higher IGFBP-3 had a lower risk (RR=0.28; 95% CI=0.12-0.66; P for trend = .005, comparing extreme quintiles). The associations were consistent during the first and the second 7-year follow-up intervals and among younger and older men. IGF-II was not associated with risk.

CONCLUSIONS

Our findings suggest that circulating IGF-I and IGFBP-3 are related to future risk of colorectal cancer.

Update on aspirin in the treatment and prevention of cardiovascular disease

The effects of low-dose aspirin on cardiovascular disease have been tested in randomized trials in 3 types of populations: (1) patients with a history of cardiovascular disease; (2) patients with evolving acute myocardial infarction (MI), and (3) apparently healthy subjects. In a very wide range of patients with prior occlusive cardiovascular disease, aspirin reduces the risks of nonfatal MI, nonfatal stroke, and vascular death. Initiating aspirin therapy within 24 hours after the onset of symptoms of an acute MI also confers conclusive reductions in the risk of nonfatal reinfarction, nonfatal stroke, and total cardiovascular death. In primary prevention trials, aspirin has been shown to reduce the risk of a first MI in men, but the data on stroke and total cardiovascular death are not sufficient to allow firm conclusions to be drawn; randomized data from studies in women are not yet available. The Women's Health Study, an ongoing large-scale trial in female health care professionals, will provide the data necessary to assess the balance of benefits and risks of aspirin in primary prevention. Until then, the decision to use aspirin in primary prevention should be based on the clinical judgment of the physician and considered as an adjunct in the management of other cardiovascular disease risk factors.

High levels of plasma C-reactive protein and future risk of age-related cataract

PURPOSE

Chronic intraocular inflammation, with or without systemic inflammation, is associated with increased risk of cataract. Whether systemic inflammation alone is associated with cataract is unknown. This study examined the association between plasma C-reactive protein (CRP), a marker of systemic inflammation, and risk of cataract.

METHODS

In the Physicians' Health Study, we recently analyzed plasma CRP levels in baseline blood specimens from 543 men who later developed cardiovascular disease, and 543 who did not. These data provided a cost-efficient means to explore whether baseline plasma CRP is associated with future risk of age-related cataract. After excluding 252 men with prior diagnosis of cataract or missing data, we followed the remaining 834 men defined by baseline CRP level for 11 years for incident cataract. We used proportional hazards regression models, stratified by cardiovascular disease status.

RESULTS

Baseline CRP was significantly higher among men who later developed cataract than levels among those who remained free of cataract, P = 0.02 (median 1.53 versus 1.23 mg/L). In a multivariable model adjusted for cardiovascular disease, randomized aspirin and beta carotene assignments, age, diabetes, cigarette smoking, alcohol consumption, body mass index, exercise, and parental history of myocardial infarction, the levels of CRP remained significantly associated with development of cataract (P = 0.001); but the association was less significant in a model using log CRP levels (P = 0.038). In exploratory analyses of a threshold effect, the excess risk was significant only among men with levels at or above the 97.5th centile (6.17 mg/L); compared to those with lower levels, the relative risk in these men was 3.00 (95% confidence interval, 1.53 to 5.91; P = 0.002). Relative risks associated with CRP levels at or above versus below the 85th, 90th, and 95th percentiles were not significant (relative risks 1.29, 1.50, and 1.77, respectively).

CONCLUSIONS

Overall, our results suggest that elevated levels of CRP are associated with future risk of cataract in these apparently healthy men. This early report raises the possibility that systemic inflammation may play a role in the pathogenesis of age-related cataract.

A prospective study of alcohol consumption and the risk of age-related macular degeneration

PURPOSE

Vascular risk factors, including alcohol intake, have been hypothesized to play a role in the development of age-related macular degeneration (AMD). We examined the relationship of alcohol intake with AMD in the Physicians' Health Study (PHS).

METHODS

The PHS was a randomized trial of aspirin and beta-carotene among 22,071 U.S. male physicians age 40 to 84 years at entry. A total of 21,041 physicians with complete data on alcohol consumption and no AMD at baseline were included in this analysis. Proportional hazards models were used to estimate relative risks (RR) and 95% confidence interval (CI).

RESULTS

During an average follow-up period of 12.5 years, 278 physicians were confirmed by medical record review to have incident AMD resulting in vision loss ( acuity 20/30 or worse). After adjusting for age, randomized treatment assignment, and other potential risk factors, the RR for > or = 1 drink/week versus < 1 drink/week was 0.97 (CI: 0.78-1.21). For categories of alcohol intake, the RRs for those reporting alcohol consumption of < 1 drink/week, 1 drink/week, 2-4 drinks/week, 5-6 drinks/week, and > or = 1 drink/day were 1.00 (referent), 1.00 (0.65-1.55), 0.68 (0.44-1.04), 1.32 (0.89-1.95), and 1.27 (0.93-1.73), respectively.

CONCLUSIONS

These prospective data indicate that alcohol intake is not appreciably associated with the risk of incident AMD. However, the width of the confidence intervals are compatible with a possible small effect (reduction or increase) in risk for low to moderate levels of alcohol intake, which warrant further investigation.

A prospective study of fibrinogen and risk of myocardial infarction in the Physicians' Health Study

OBJECTIVES

We examined the association of baseline plasma fibrinogen with future risk of myocardial infarction (MI) in the Physicians' Health Study.

BACKGROUND

Elevated plasma fibrinogen increases and low dose aspirin decreases risk of MI. However, prospective data are limited about their interrelationships.

METHODS

Blood samples were prospectively collected at baseline from 14,916 men in the Physicians' Health Study, aged 40 to 84 years, who were randomly assigned to take aspirin (325 mg every other day) or placebo for 5 years. We measured baseline plasma fibrinogen among 199 incident cases of MI and 199 age- and smoking-matched control subjects free of cardiovascular disease at the time of the case's diagnosis.

RESULTS

Cases had significantly higher baseline fibrinogen levels (geometric mean: 262 mg/dl) than did control subjects (245 mg/dl, p = 0.02). Those with high fibrinogen levels (> or =343 mg/dl, the 90th percentile distribution of the control subjects) had a twofold increase in MI risk (age- and smoking-adjusted relative risk = 2.09, 95% confidence interval = 1.15 to 3.78) compared with those with fibrinogen below 343 mg/dl. Adjustment for lipids and other coronary risk factors as well as randomized aspirin assignment did not materially change the result. Furthermore, we observed no interaction between fibrinogen level and aspirin treatment.

CONCLUSIONS

Among these apparently healthy U.S. male physicians, fibrinogen is associated with increased risk of future MI independent of other coronary risk factors, atherogenic factors such as lipids and antithrombotics such as aspirin.

Lower prostate cancer risk in men with elevated plasma lycopene levels: results of a prospective analysis

Dietary consumption of the carotenoid lycopene (mostly from tomato products) has been associated with a lower risk of prostate cancer. Evidence relating other carotenoids, tocopherols, and retinol to prostate cancer risk has been equivocal. This prospective study was designed to examine the relationship between plasma concentrations of several major antioxidants and risk of prostate cancer. We conducted a nested case-control study using plasma samples obtained in 1982 from healthy men enrolled in the Physicians' Health Study, a randomized, placebo-controlled trial of aspirin and beta-carotene. Subjects included 578 men who developed prostate cancer within 13 years of follow-up and 1294 age- and smoking status-matched controls. We quantified the five major plasma carotenoid peaks (alpha- and beta-carotene, beta-cryptoxanthin, lutein, and lycopene) plus alpha- and gamma-tocopherol and retinol using high-performance liquid chromatography. Results for plasma beta-carotene are reported separately. Odds ratios (ORs), 95% confidence intervals (Cls), and Ps for trend were calculated for each quintile of plasma antioxidant using logistic regression models that allowed for adjustment of potential confounders and estimation of effect modification by assignment to either active beta-carotene or placebo in the trial. Lycopene was the only antioxidant found at significantly lower mean levels in cases than in matched controls (P = 0.04 for all cases). The ORs for all prostate cancers declined slightly with increasing quintile of plasma lycopene (5th quintile OR = 0.75, 95% CI = 0.54-1.06; P, trend = 0.12); there was a stronger inverse association for aggressive prostate cancers (5th quintile OR = 0.56, 95% CI = 0.34-0.91; P, trend = 0.05). In the placebo group, plasma lycopene was very strongly related to lower prostate cancer risk (5th quintile OR = 0.40; P, trend = 0.006 for aggressive cancer), whereas there was no evidence for a trend among those assigned to beta-carotene supplements. However, in the beta-carotene group, prostate cancer risk was reduced in each lycopene quintile relative to men with low lycopene and placebo. The only other notable association was a reduced risk of aggressive cancer with higher alpha-tocopherol levels that was not statistically significant. None of the associations for lycopene were confounded by age, smoking, body mass index, exercise, alcohol, multivitamin use, or plasma total cholesterol level. These results concur with a recent prospective dietary analysis, which identified lycopene as the carotenoid with the clearest inverse relation to the development of prostate cancer. The inverse association was particularly apparent for aggressive cancer and for men not consuming beta-carotene supplements. For men with low lycopene, beta-carotene supplements were associated with risk reductions comparable to those observed with high lycopene. These data provide further evidence that increased consumption of tomato products and other lycopene-containing foods might reduce the occurrence or progression of prostate cancer.

Prospective study of Chlamydia pneumoniae IgG seropositivity and risks of future myocardial infarction

BACKGROUND

Chlamydia pneumoniae has been hypothesized to play a role in atherothrombosis. However, prospective data relating exposure to Chlamydia pneumoniae and risks of future myocardial infarction (MI) are sparse.

METHODS AND RESULTS

In a prospective cohort of nearly 15 000 healthy men, we measured IgG antibodies directed against Chlamydia pneumoniae in blood samples collected at baseline from 343 study participants who subsequently reported a first MI and from an equal number of age- and smoking-matched control subjects who did not report vascular disease during a 12-year follow-up period. The proportion of study subjects with IgG antibodies directed against Chlamydia increased with age and cigarette consumption. However, prevalence rates of Chlamydia IgG seropositivity were virtually identical at baseline among men who subsequently reported first MI compared with age- and smoking-matched control subjects. Specifically, the relative risks of future MI associated with Chlamydia pneumoniae IgG titers >/=1:16, 1:32, 1:64, 1:128, and 1:256 were 1.1, 1.0, 1.1, 1.0, and 0.8, respectively (all probability values not significant). There was no association in analyses adjusted for other risk factors, evaluating early as compared with late events, or among nonsmokers. Further, there was no association between seropositivity and concentration of C-reactive protein, a marker of inflammation that predicts MI risk in this cohort.

CONCLUSIONS

In a large-scale study of socioeconomically homogeneous men that controlled for age, smoking, and other cardiovascular risk factors, we found no evidence of association between Chlamydia pneumoniae IgG seropositivity and risks of future MI.

G20210A mutation in prothrombin gene and risk of myocardial infarction, stroke, and venous thrombosis in a large cohort of US men

BACKGROUND

A single base pair mutation in the prothrombin gene has recently been identified that is associated with increased prothrombin levels. Whether this mutation increases the risks of arterial and venous thrombosis among healthy individuals is controversial.

METHODS AND RESULTS

In a prospective cohort of 14 916 men, we determined the prevalence of the G20210A prothrombin gene variant in 833 men who subsequently developed myocardial infarction, stroke, or venous thrombosis (cases) and in 1774 age- and smoking status-matched men who remained free of thrombosis during a 10-year follow-up (control subjects). Gene sequencing was used to confirm mutation status in a subgroup of participants. Overall, carrier rates for the G20210A mutation were similar among case and control subjects; the relative risk of developing any thrombotic event in association with the 20210A allele was 1.05 (95% CI, 0.7 to 1.6; P=0.8). We observed no evidence of association between mutation and myocardial infarction (RR=0.8, P=0.4) or stroke (RR=1.1, P=0.8). For venous thrombosis, a modest nonsignificant increase in risk was observed (RR=1.7, P=0.08) that was smaller in magnitude than that associated with factor V Leiden (RR=3.0, P<0. 001). Nine individuals carried both the prothrombin mutation and factor V Leiden (5 controls and 4 cases). One individual, a control subject, was homozygous for the prothrombin mutation.

CONCLUSIONS

In a large cohort of US men, the G20210A prothrombin gene variant was not associated with increased risk of myocardial infarction or stroke. For venous thrombosis, risk estimates associated with the G20210A mutation were smaller in magnitude than risk estimates associated with factor V Leiden.

Vasectomy and subsequent cardiovascular disease in US physicians

Due to previous animal research suggesting accelerated atherosclerosis following vasectomy, we examined whether vasectomy increases the risk of subsequent cardiovascular disease (CVD), including myocardial infarction (MI), angina pectoris, coronary revascularization, and stroke, in the US Physicians' Health Study. Of 22,071 US male physicians participating in the study, aged 40 to 84 years at entry and free from cardiovascular disease and cancer, 21,028 reported on the 60-month questionnaire whether they had undergone vasectomy prior to randomization. Of the 4546 physicians with vasectomy, 1159 had undergone the procedure at least 15 years before entry. During 258,892 person-years of follow-up, we documented 773 cases of MI (719 nonfatal and 54 fatal), 1907 cases of angina pectoris or coronary revascularization, and 604 confirmed cases of ischemic or hemorrhagic stroke (566 nonfatal and 38 fatal). When compared to men without prior vasectomy, the multivariate relative risk (RR) of total MI adjusted for age and other coronary risk factors was 0.94 (95% confidence interval [CI], 0.77-1.14) among men with vasectomy. Risk estimates for fatal and nonfatal events did not appreciably differ from each other. For angina or coronary revascularization or both, the multivariate relative risk was 0.99 (0.88-1.12) and for total stroke the RR was 0.95 (0.75-1.21). For men who had undergone vasectomy 15 or more years previously, the multivariate relative risks were 0.98 (0.73-1.32) for total MI, 1.17 (0.87-1.57) for total stroke, and 1.12 (0.94-1.35) for angina/revascularization. These results provide reassuring evidence that vasectomy does not materially increase the risk of subsequent cardiovascular disease, even 15 or more years following the procedure.