Triggering of sudden death from cardiac causes by vigorous exertion

BACKGROUND

Retrospective and cross-sectional data suggest that vigorous exertion can trigger cardiac arrest or sudden death and that habitual exercise may diminish this risk. However, the role of physical activity in precipitating or preventing sudden death has not been assessed prospectively in a large number of subjects.

METHODS

We used a prospective, nested case-crossover design within the Physicians' Health Study to compare the risk of sudden death during and up to 30 minutes after an episode of vigorous exertion with that during periods of lighter exertion or none. We then evaluated whether habitual vigorous exercise modified the risk of sudden death that was associated with vigorous exertion. In addition, the relation of vigorous exercise to the overall risk of sudden death and nonsudden death from coronary heart disease was assessed.

RESULTS

During 12 years of follow-up, 122 sudden deaths were confirmed among the 21,481 male physicians who were initially free of self-reported cardiovascular disease and who provided information on their habitual level of exercise at base line. The relative risk of-sudden death during and up to 30 minutes after vigorous exertion was 16.9 (95 percent confidence interval, 10.5 to 27.0; P<0.001). However, the absolute risk of sudden death during any particular episode of vigorous exertion was extremely low (1 sudden death per 1.51 million episodes of exertion). Habitual vigorous exercise attenuated the relative risk of sudden death that was associated with an episode of vigorous exertion (P value for trend=0.006). The base-line level of exercise was not associated with the overall risk of subsequent sudden death.

CONCLUSIONS

These prospective data from a study of U.S. male physicians suggest that habitual vigorous exercise diminishes the risk of sudden death during vigorous exertion.

Systolic and diastolic blood pressure, pulse pressure, and mean arterial pressure as predictors of cardiovascular disease risk in Men

We compared systolic blood pressure (SBP), diastolic blood pressure (DBP), pulse pressure (PP), and mean arterial pressure (MAP) in predicting the risk of cardiovascular disease (CVD), stratifying results at age 60 years, when DBP decreases while SBP continues to increase. We prospectively followed 11 150 male physicians with no history of CVD or antihypertensive treatment through the 2-year questionnaire, after which follow-up began. Reported blood pressure was averaged from both the baseline and 2-year questionnaires. During a median follow-up of 10.8 years, there were 905 cases of incident CVD. For men aged <60 years (n=8743), those in the highest versus lowest quartiles of average SBP (>/=130 versus <116 mm Hg), DBP (>/=81 versus <73 mm Hg), and MAP (>/=97 versus <88 mm Hg) had relative risks (RRs) of CVD of 2.16, 2.23, and 2.52, respectively. Models with average MAP and PP did not add information compared with models with MAP alone (P>0.05). For men aged >/=60 years (n=2407), those in the highest versus lowest quartiles of average SBP (>/=135 versus <120 mm Hg), PP (>/=55 versus <44 mm Hg), and MAP (>/=99 versus <91 mm Hg) had RRs of CVD of 1.69, 1.83, and 1.43, respectively. The addition of other blood pressure measures did not add information compared with average SBP or PP alone (all P>0.05). These data suggest that average SBP, DBP, and MAP strongly predict CVD among younger men, whereas either average SBP or PP predicts CVD among older men. More research should distinguish whether MAP, highly correlated with SBP and DBP, better predicts CVD.

A prospective study of cigarette smoking and the incidence of diabetes mellitus among US male physicians

PURPOSE

To determine the association between cigarette smoking and the incidence of type 2 diabetes mellitus.

SUBJECTS AND METHODS

We studied 21,068 US male physicians aged 40 to 84 years in the Physicians' Health Study who were initially free of diagnosed diabetes mellitus, cardiovascular disease, and cancer. Information about cigarette smoking and other risk indicators was obtained at baseline. The primary outcome was reported diagnosis of type 2 diabetes mellitus.

RESULTS

During 255,830 person-years of follow-up, 770 new cases of type 2 diabetes mellitus were identified. Smokers had a dose-dependent increased risk of developing type 2 diabetes mellitus: compared with never smokers, the age-adjusted relative risk was 2.1 (95% confidence interval [CI]: 1.7 to 2.6) for current smokers of > or = 20 cigarettes per day, 1.4 (95% CI: 1.0 to 2.0) for current smokers of <20 cigarettes per day, and 1.2 (95% CI: 1.0 to 1.4) for past smokers. After multivariate adjustment for body mass index, physical activity, and other risk factors, the relative risks were 1.7 (95% CI: 1.3 to 2.3) for current smokers of > or = 20 cigarettes per day, 1.5 (95% CI: 1.0 to 2.2) for current smokers of <20 cigarettes per day, and 1.1 (95% CI: 1.0 to 1.4) for past smokers. Total pack-years of cigarette smoking was also associated with the risk of type 2 diabetes mellitus (P for trend <0.001).

CONCLUSIONS

These prospective data support the hypothesis that cigarette smoking is an independent and modifiable determinant of type 2 diabetes mellitus.

Combining annual blood pressure measurements in childhood to improve prediction of young adult blood pressure

Tracking correlations of blood pressure (BP) have been reported between levels measured in a single year during both childhood and adulthood. Because of the variability of BP, these correlations increase with the number of visits and measurements per visit in each year. It remains unclear, however, whether such correlations would improve further by combining BP data collected over several years. From 1978-1981, BP was measured annually in a cohort of 339 children in East Boston, MA, at four visits one week apart with three measurements per visit. Of this cohort, then aged 18-26 years, 316 were re-examined in 1989-1990 at three visits one week apart with three measures per visit. Tracking correlations were estimated from levels measured in a single year as well as means averaged over several years in childhood, adjusting for age, year of measurement, as well as smoking, alcohol and oral contraceptive use. Multivariate models were fit to estimate tracking correlations from childhood to young adulthood adjusting for within-person variability. Using a single year in childhood, these were 0.49 in boys and 0.59 in girls for systolic BP and 0.39 and 0.48 for diastolic BP (all p<0.001). Using the long-term average in childhood and adjusting for variability across years, these values were 0.55 in boys and 0.66 in girls for systolic BP and 0.47 and 0.57 for diastolic BP (all p<0.001). We observed concomitant increases in the predictive value of childhood BP for young adult BP. These results suggest that averaging BP over at least two years during childhood increases tracking correlations and improves the prediction of adult values from childhood levels.

Pulse pressure and mortality in older people

BACKGROUND

In older people, observational data are unclear concerning the relationships of systolic and diastolic blood pressure with cardiovascular and total mortality. We examined which combinations of systolic, diastolic, pulse, and mean arterial pressure best predict total and cardiovascular mortality in older adults.

METHODS

In 1981, the National Institute on Aging initiated its population-based Established Populations for Epidemiologic Studies of the Elderly in 3 communities. At baseline, 9431 participants, aged 65 to 102 years, had blood pressure measurements, along with measures of medical history, use of medications, disability, and physical function. During an average follow-up of 10. 6 years among survivors, 4528 participants died, 2304 of cardiovascular causes.

RESULTS

In age- and sex-adjusted survival analyses, the lowest overall death rate occurred among those with systolic pressure less than 130 mm Hg and diastolic pressure 80 to 89 mm Hg; relative to this group, the highest death rate occurred in those with systolic pressure of 160 mm Hg or more and diastolic pressure less than 70 mm Hg (relative risk, 1.90; 95% confidence interval, 1.47-2.46). Both low diastolic pressure and elevated systolic pressure independently predicted increases in cardiovascular (P<.001) and total (P<.001) mortality. Pulse pressure correlated strongly with systolic pressure (R = 0.82) but was a slightly stronger predictor of both cardiovascular and total mortality. In a model containing pulse pressure and other potentially confounding variables, diastolic pressure (P =.88) and mean arterial pressure (P =.11) had no significant association with mortality.

CONCLUSIONS

Pulse pressure appears to be the best single measure of blood pressure in predicting mortality in older people and helps explain apparently discrepant results for low diastolic blood pressure.

Fruit and vegetable intake and risk of cardiovascular disease: the Women's Health Study

BACKGROUND

Prospective data relating fruit and vegetable intake to cardiovascular disease (CVD) risk are sparse, particularly for women.

OBJECTIVE

In a large, prospective cohort of women, we examined the hypothesis that higher fruit and vegetable intake reduces CVD risk.

DESIGN

In 1993 we assessed fruit and vegetable intake among 39876 female health professionals with no previous history of CVD or cancer by use of a detailed food-frequency questionnaire. We subsequently followed these women for an average of 5 y for incidence of nonfatal myocardial infarction (MI), stroke, percutaneous transluminal coronary angioplasty, coronary artery bypass graft, or death due to CVD.

RESULTS

During 195647 person-years of follow-up, we documented 418 incident cases of CVD including 126 MIs. After adjustment for age, randomized treatment status, and smoking, we observed a significant inverse association between fruit and vegetable intake and CVD risk. For increasing quintiles of total fruit and vegetable intake (median servings/d: 2. 6, 4.1, 5.5, 7.1, and 10.2), the corresponding relative risks (RRs) were 1.0 (reference), 0.78, 0.72, 0.68, and 0.68 (95% CI comparing the 2 extreme quintiles: 0.51, 0.92; P: for trend = 0.01). An inverse, though not statistically significant, trend remained after additional adjustment for other known CVD risk factors, with RRs of 1.0, 0.75, 0.83, 0.80, and 0.85 (95% CI for extreme quintiles: 0.61, 1.17). After excluding participants with a self-reported history of diabetes, hypertension, or high cholesterol at baseline, the multivariate-adjusted RR was 0.45 when extreme quintiles were compared (95% CI: 0.22, 0.91; P: for trend = 0.09). Higher fruit and vegetable intake was also associated with a lower risk of MI, with an adjusted RR of 0.62 for extreme quintiles (95% CI: 0.37, 1.04; P: for trend = 0.07).

CONCLUSION

These data suggest that higher intake of fruit and vegetables may be protective against CVD and support current dietary guidelines to increase fruit and vegetable intake.

Seven-year changes in alcohol consumption and subsequent risk of cardiovascular disease in men

BACKGROUND

Few studies have examined whether changes in alcohol consumption influence future cardiovascular risk.

OBJECTIVE

To examine whether 7-year changes in alcohol consumption are associated with the subsequent risk of cardiovascular disease (CVD).

METHODS

We prospectively followed up 18,455 men aged 40 to 84 years from the Physicians' Health Study with no history of CVD or cancer. Alcohol consumption was reported on the baseline and the 7-year questionnaires; follow-up for this analysis began after the 7-year questionnaire (median follow-up, 5.8 years). There were 1091 CVD cases, including myocardial infarction, angina pectoris, revascularization, stroke, and CVD-related death.

RESULTS

Among men initially consuming 1 drink per week or less (n=7360), those with moderate increases (>1 to <6 drinks per week) in alcohol consumption had a borderline significant (P=.05) 29% reduced risk of CVD compared with men with no changes (-1 to 1 drink per week). Among men initially consuming greater than 1 to 6 drinks per week (n=6612), those with moderate increases had a nonsignificant (P=.32) 15% decrease in CVD risk compared with men with no changes. Finally, among men initially consuming 1 drink per day or more (n=4483), those who increased intake had a 63% increased risk of CVD compared with men with no changes.

CONCLUSIONS

These prospective data suggest that, among men with initially low alcohol consumption (</=1 drink per week), a subsequent moderate increase in alcohol consumption may lower their CVD risk. The possible reduction in CVD risk from increasing alcohol intake did not extend to men initially consuming greater than 1 drink per week. Given the potential risks and benefits associated with alcohol consumption, physician counseling of patients must be individualized in the context of the primary prevention of CVD.

A prospective study of whole-grain intake and risk of type 2 diabetes mellitus in US women

OBJECTIVES

This study examined the association between intake of whole vs refined grain and the risk of type 2 diabetes mellitus.

METHODS

We used a food frequency questionnaire for repeated dietary assessments to prospectively evaluate the relation between whole-grain intake and the risk of diabetes mellitus in a cohort of 75,521 women aged 38 to 63 years without a previous diagnosis of diabetes or cardiovascular disease in 1984.

RESULTS

During the 10-year follow-up, we confirmed 1879 incident cases of diabetes mellitus. When the highest and the lowest quintiles of intake were compared, the age and energy-adjusted relative risks were 0.62 (95% confidence interval [CI] = 0.53, 0.71, P trend < .0001) for whole grain, 1.31 (95% CI = 1.12, 1.53, P trend = .0003) for refined grain, and 1.57 (95% CI = 1.36, 1.82, P trend < .0001) for the ratio of refined- to whole-grain intake. These findings remained significant in multivariate analyses. The findings were most evident for women with a body mass index greater than 25 and were not entirely explained by dietary fiber, magnesium, and vitamin E.

CONCLUSIONS

These findings suggest that substituting whole- for refined-grain products may decrease the risk of diabetes mellitus.

Smoking cessation and risk of age-related cataract in men

CONTEXT

Although cigarette smoking has been shown to be a risk factor for age-related cataract, data are inconclusive on the risk of cataract in individuals who quit smoking.

OBJECTIVE

To examine the association between smoking cessation and incidence of age-related cataract.

DESIGN

Prospective cohort study conducted from 1982 through 1997, with an average follow-up of 13.6 years.

SETTING AND PARTICIPANTS

A total of 20,907 US male physicians participating in the Physicians' Health Study I who did not have a diagnosis of age-related cataract at baseline and had reported their level of smoking at baseline.

MAIN OUTCOME MEASURES

Incident age-related cataract defined as self-report confirmed by medical record review, diagnosed after study randomization and responsible for vision loss to 20/30 or worse, and surgical extraction of incident age-related cataract, in relation to smoking status and years since quitting smoking.

RESULTS

At baseline, 11% were current smokers, 39% were past smokers, and 50% were never smokers. Average reported cumulative dose of smoking at baseline was approximately 2-fold greater in current than in past smokers (35.8 vs 20.5 pack-years). Two thousand seventy-four incident cases of age-related cataract and 1193 cataract extractions were confirmed during follow-up. Compared with current smokers, multivariate relative risks (RRs) of cataract in past smokers who quit smoking fewer than 10 years, 10 to fewer than 20 years, and 20 or more years before the study were 0.79 (95% confidence interval [CI], 0.64-0.98), 0.73 (95% CI, 0.61-0.88), and 0.74 (95% CI, 0.63-0.87), respectively, after adjustment for other risk factors for cataract and age at smoking inception. The RR for never smokers was 0.64 (95% CI, 0.54-0.76). The reduced risk in past smokers was principally due to a lower total cumulative dose (RR of cataract for increase of 10 pack-years of smoking, 1.07; 95% CI, 1.04-1.10). A benefit of stopping smoking independent of cumulative dose was suggested in some analyses. Results for cataract extraction were similar.

CONCLUSION

These prospective data indicate that while some smoking-related damage to the lens may be reversible, smoking cessation reduces the risk of cataract primarily by limiting total dose-related damage to the lens. JAMA. 2000;284:713-716

Alcohol consumption and risk of coronary heart disease by diabetes status

BACKGROUND

An inverse association between moderate alcohol consumption and coronary heart disease (CHD) has been observed in several epidemiological studies. To assess whether a similar association exists among diabetics, we examined the relation between light to moderate alcohol consumption and CHD in men with and without diabetes mellitus in a prospective cohort study.

METHODS AND RESULTS

A total of 87 938 US physicians (2790 with diagnosed diabetes mellitus) who were invited to participate in the Physicians' Health Study and were free of myocardial infarction, stroke, cancer, or liver disease at baseline were followed for an average of 5.5 years for death with CHD as the underlying cause. During 480 876 person-years of follow-up, 850 deaths caused by CHD were documented: 717 deaths among nondiabetic men and 133 deaths among diabetic men. Among men without diabetes at baseline, the relative risk estimates for those reporting rarely/never, monthly, weekly, and daily alcohol consumption were 1.00 (referent), 1.02, 0. 82, and 0.61 (95% CI 0.49 to 0.78; P for trend <0.0001) after adjustment for age, aspirin use, smoking, physical activity, body mass index, and history of angina, hypertension, and high cholesterol. Among men with diabetes at baseline, the relative risk estimates were 1.00 (referent), 1.11, 0.67, and 0.42 (95% CI 0.23 to 0.77; P for trend=0.0019).

CONCLUSIONS

These results suggest that light to moderate alcohol consumption is associated with similar risk reductions in CHD among diabetic and nondiabetic men.

Plasma concentration of soluble vascular cell adhesion molecule-1 and subsequent cardiovascular risk

OBJECTIVES

The purpose of this study was to evaluate whether soluble vascular cell adhesion molecule-1 (sVCAM-1) is a marker for increased cardiovascular risk.

BACKGROUND

Soluble forms of cellular adhesion molecules (CAMs) may be useful markers of endothelial activation and local or systemic inflammation. Recent studies indicate that plasma concentration of soluble intercellular adhesion molecule-1 (sICAM-1) is elevated many years before a first myocardial infarction (MI) occurs. However, only a few prospective studies have evaluated whether sVCAM-1 is also a marker for increased cardiovascular risk.

METHODS

Baseline plasma samples were obtained prospectively from 14,916 healthy participants in the Physicians' Health Study. In a nested, case-control study design, the plasma concentration of sVCAM-1 was measured in 474 men with confirmed MI during the nine-year follow-up period, and in an equal number of control subjects who remained free of reported cardiovascular disease and who were matched for age, smoking status and length of follow-up.

RESULTS

No significant difference in the median baseline sVCAM-1 concentration was found between case and control subjects (638 vs. 634 ng/ml; p = NS). Cardiovascular risk was similar between patients with sVCAM-1 levels in the highest quartile and those in the lowest quartile, in both crude (relative risk [RR] 1.28, 95% confidence interval [CI] 0.85 to 1.92) and adjusted (RR 1.17, 95% CI 0.71 to 1.91) matched-pairs analyses.

CONCLUSIONS

In contrast to previous data on sICAM-1, we found no evidence of an association between sVCAM-1 levels and the risk of future MI in a large cohort of apparently healthy men. These data suggest important pathophysiologic differences between sVCAM-1 and sICAM-1 in the genesis of atherothrombosis.

Effects of beta-carotene supplementation on cancer incidence by baseline characteristics in the Physicians' Health Study (United States)

OBJECTIVES

The Physicians' Health Study (PHS) was a randomized trial of beta-carotene (50 mg, alternate days) and aspirin in primary prevention of cancer and cardiovascular disease among 22,071 US male physicians. This report updates results for beta-carotene and examines effect modification by baseline characteristics.

METHODS

Beta-carotene's effect on cancer over nearly 13 years was examined overall and within subgroups defined by baseline characteristics using proportional-hazards models.

RESULTS

2667 incident cancers were confirmed, with 1117 prostate, 267 colon, and 178 lung cancers. There were no significant differences with supplementation in total (relative risk (RR) = 1.0, 95% confidence interval (CI) = 0.9-1.0); prostate (RR = 1.0, 95% CI = 0.9-1.1); colon (RR = 0.9, 95% CI = 0.7-1.2); or lung (RR = 0.9, 95% CI = 0.7-1.2) cancer, and no differences over time. In subgroup analyses, total cancer was modestly reduced with supplementation among those aged 70+ years (RR = 0.8, 95% CI = 0.7-1.0), daily drinkers of alcohol (RR = 0.9, 95% CI = 0.8-1.0), and those in the highest BMI quartile (RR = 0.9, 95% CI = 0.7-1.0). Prostate cancer was reduced with supplementation among those in the highest BMI quartile (RR = 0.8, 95% CI = 0.6-1.0), and colon cancer was reduced among daily drinkers of alcohol (RR = 0.5, 95% CI = 0.3-0.8).

CONCLUSIONS

The PHS found no overall effect of beta-carotene on total cancer, or the three most common site-specific cancers. The possibility of risk reduction within specific subgroups remains.

Two-year changes in blood pressure and subsequent risk of cardiovascular disease in men

BACKGROUND-It is unclear whether, given a current blood pressure level, the previous 2-year change in blood pressure adds important predictive information for cardiovascular disease (CVD). METHODS AND RESULTS-We conducted a prospective cohort study of 11 150 middle-aged and older men reporting blood pressure in the Physicians' Health Study. These men had no history of CVD or antihypertensive medication use through the time of the 2-year follow-up questionnaire; after this time, follow-up for the current study began. A total of 905 incident cases of CVD (705 cases of coronary heart disease and 200 cases of stroke) occurred during a median follow-up of 10.8 years. After controlling for current blood pressure and other coronary risk factors, we found that previous 2-year changes in systolic blood pressure were not associated with the risk of CVD. A similar lack of association was found for individual end points of coronary heart disease and stroke. However, previous 2-year changes in diastolic blood pressure (DBP) may be inversely associated with the risk of CVD (linear trend, P=0.049) independent of coronary risk factors and current DBP. In subgroup analyses, previous 2-year blood pressure changes only added information in leaner men (body mass index <24.39 kg/m(2)). CONCLUSIONS-In this normotensive population of men, the prior 2-year change in DBP, but not systolic blood pressure, may add information to current levels in relation to the risk of CVD. Clinicians may need to consider the previous pattern of DBP change when considering the risk associated with the current DBP level. These data require confirmation in other studies in which blood pressure is measured.

Cigarette smoking and risk of prostate cancer in the physicians' health study (United States)

To assess whether cigarette smoking is associated with prostate cancer incidence or mortality, we analyzed a large cohort of 22,071 men, aged 40-84 at baseline, in the Physicians' Health Study. During an average of 12.5 years of follow-up, we documented 996 cases of prostate cancer, including 113 fatal cases. Men were categorized according to smoking status, total pack-years smoked, and duration of smoking. We used Cox proportional hazard models to estimate the relative risks associated with smoking. Compared to never smokers, the age-adjusted relative risks (RR) of total prostate cancer were 1. 14 (95% confidence interval [CI] = 1.00-1.30) for past smokers, 1.10 (95% CI = 0.78-1.55) for current smokers of less than 20 cigarettes per day, and 1.10 (95% CI = 0.84-1.44) for current smokers of 20 or more cigarettes per day. Adjustment for body mass index, height, alcohol intake, and physical activity did not materially alter these findings. No significant association was observed in analyses of total pack-years smoked or duration of smoking. The results were similar for non-fatal and fatal prostate cancer. These data indicate no material association between cigarette smoking and prostate cancer incidence or mortality.

Baseline self-reported cataract and subsequent mortality in Physicians' Health Study I

PURPOSE

To examine whether a reported history of cataract, a possible marker of aging, is associated with future mortality.

METHODS

Participants were 18,669 of the 22,071 U.S. male physicians enrolled in the Physicians' Health Study I who had complete information at study entry, including self-report of presence or absence of baseline cataract. Participants were without a previous history of myocardial infarction, stroke, transient cerebral ischemia, or cancer (except non-melanoma skin cancer). Reported deaths were confirmed by an End Points Committee of physicians.

RESULTS

A total of 581 participants reported a personal history of cataract at baseline. During an average of 12.4 years of follow-up, there were 1,514 deaths including 496 due to cardiovascular (CV) and 1,018 due to non-CV causes. After adjustment for differences in age, men who reported cataract at baseline had a non-significant 9% increased risk of death from any cause compared to men who did not report cataract (RR, 1.09; 95% CI, 0.91-1.30). The RRs were 1.03 (95% CI, 0.75-1.41) for CV death and 1.12 (95% CI, 0.90-1.40) for non-CV death. Adjustment for other risk factors had little effect on these estimates. Similar results were obtained in analyses conducted separately among those with and without self-reported diabetes at baseline.

CONCLUSIONS

These results from a population of generally healthy physicians indicate that a report of a history of cataract is not associated with any material increase in mortality after adjustment for differences in age between men with and without cataract. Additional investigation of this cohort is in progress to determine whether incident age-related cataracts as well as their subtypes, confirmed by medical record review, are associated with increased mortality.

A prospective study of dietary glycemic load, carbohydrate intake, and risk of coronary heart disease in US women

BACKGROUND

Little is known about the effects of the amount and type of carbohydrates on risk of coronary heart disease (CHD).

OBJECTIVE

The objective of this study was to prospectively evaluate the relations of the amount and type of carbohydrates with risk of CHD.

DESIGN

A cohort of 75521 women aged 38-63 y with no previous diagnosis of diabetes mellitus, myocardial infarction, angina, stroke, or other cardiovascular diseases in 1984 was followed for 10 y. Each participant's dietary glycemic load was calculated as a function of glycemic index, carbohydrate content, and frequency of intake of individual foods reported on a validated food-frequency questionnaire at baseline. All dietary variables were updated in 1986 and 1990.

RESULTS

During 10 y of follow-up (729472 person-years), 761 cases of CHD (208 fatal and 553 nonfatal) were documented. Dietary glycemic load was directly associated with risk of CHD after adjustment for age, smoking status, total energy intake, and other coronary disease risk factors. The relative risks from the lowest to highest quintiles of glycemic load were 1.00, 1.01, 1. 25, 1.51, and 1.98 (95% CI: 1.41, 2.77 for the highest quintile; P for trend < 0.0001). Carbohydrate classified by glycemic index, as opposed to its traditional classification as either simple or complex, was a better predictor of CHD risk. The association between dietary glycemic load and CHD risk was most evident among women with body weights above average ¿ie, body mass index (in kg/m(2)) >/= 23.

CONCLUSION

These epidemiologic data suggest that a high dietary glycemic load from refined carbohydrates increases the risk of CHD, independent of known coronary disease risk factors.

Plasma concentration of interleukin-6 and the risk of future myocardial infarction among apparently healthy men

BACKGROUND

Interleukin-6 (IL-6) plays a central role in inflammation and tissue injury. However, epidemiological data evaluating the role of IL-6 in atherogenesis are sparse.

METHODS AND RESULTS

In a prospective study involving 14 916 apparently healthy men, we measured baseline plasma concentration of IL-6 in 202 participants who subsequently developed myocardial infarction (MI) and in 202 study participants matched for age and smoking status who did not report vascular disease during a 6-year follow-up. Median concentrations of IL-6 at baseline were higher among men who subsequently had an MI than among those who did not (1.81 versus 1. 46 pg/mL; P=0.002). The risk of future MI increased with increasing quartiles of baseline IL-6 concentration (P for trend <0.001) such that men in the highest quartile at entry had a relative risk 2.3 times higher than those in the lowest quartile (95% CI 1.3 to 4.3, P=0.005); for each quartile increase in IL-6, there was a 38% increase in risk (P=0.001).This relationship remained significant after adjustment for other cardiovascular risk factors, was stable over long periods of follow-up, and was present in all low-risk subgroups, including nonsmokers. Although the strongest correlate of IL-6 in these data was C-reactive protein (r=0.43, P<0.001), the relationship of IL-6 with subsequent risk remained after control for this factor (P<0.001).

CONCLUSIONS

In apparently healthy men, elevated levels of IL-6 are associated with increased risk of future MI. These data thus support a role for cytokine-mediated inflammation in the early stages of atherogenesis.

Alcohol consumption and risk of type 2 diabetes mellitus among US male physicians

OBJECTIVE

To examine the association between low to moderate alcohol consumption and the incidence of type 2 diabetes mellitus (DM) in men.

DESIGN

Prospective cohort study.

SUBJECTS AND METHODS

Over an average period of 12.1 years, we evaluated 20 951 participants in the Physicians' Health Study between ages 40 and 84 years who were free of cardiovascular disease, cancer, and diabetes and provided data on alcohol consumption at baseline.

MAIN OUTCOME MEASURE

Type 2 DM diagnosed after randomization.

RESULTS

Among 20 951 physicians, 766 cases of incident DM were reported over an average follow-up period of 12.1 years. After adjustment for age, randomized treatment assignment, smoking, physical activity, and body mass index, the relative risk estimates and 95% confidence intervals for those reporting alcohol use of rarely/ never, 1 to 3 drinks per month, 1 drink per week, 2 to 4 drinks per week, 5 to 6 drinks per week, and 1 or more drinks per day were 1.00 (referent), 1.03 (0.80-1.33), 0.89 (0.70-1.14), 0.74 (0.59-0.93), 0.67 (0.51-0.89), and 0.57 (0.45-0.73), respectively (linear trend, P<.001). Additional adjustment for baseline history of hypertension, high cholesterol level, or parental history of myocardial infarction or family history of diabetes (data collected at 9 years) did not materially alter the results. These associations persisted in analyses stratified by age, smoking status, body mass index, physical activity, and family history of DM.

CONCLUSION

These data indicate that apparently healthy men who self-select for light to moderate alcohol consumption have a decreased subsequent risk of type 2 DM.

Self-selected posttrial aspirin use and subsequent cardiovascular disease and mortality in the physicians' health study

BACKGROUND

The randomized aspirin component of the Physicians' Health Study (PHS) was terminated early, after 5 years, primarily because of the emergence of a statistically extreme (P<.00001) 44% reduction of first myocardial infarction (MI) among those assigned to aspirin. As a result, there were insufficient numbers of strokes or cardiovascular disease (CVD)-related deaths to evaluate these end points definitively.

METHODS

Data on self-selected aspirin use were collected until the beta carotene component ended as scheduled after 12 years. Posttrial use of aspirin was assessed at the 7-year follow-up among 18 496 participants with no previous reported CVD. Randomized and posttrial observational results in the PHS were compared, and differences between those self-selecting aspirin and those not were examined.

RESULTS

At 7 years, 59.5% of participants without CVD reported self-selected aspirin use for at least 180 d/y, and 20.8% for 0 to 13 d/y. Use was significantly associated with family history of MI, hypertension, elevated cholesterol levels, body mass index, alcohol consumption, exercise, and use of vitamin E supplements. In multivariate analyses, self-selected aspirin use for at least 180 vs 0 to 13 d/y was associated with lower risk for subsequent MI (relative risk [RR], 0.72; 95% confidence interval [CI], 0.55-0.95), no relation with stroke (RR, 1.02; 95% CI, 0.74-1.39), and significant reductions in CVD-related (RR, 0.65; CI, 0.47-0.89) and total mortality (RR, 0.64; CI, 0.54-0.77).

CONCLUSION

These associations between self-selected aspirin use and CVD risk factors increase the likelihood of residual confounding and emphasize the need for large-scale randomized trials, such as the ongoing Women's Health Study, to detect reliably the most plausible small to moderate effects of aspirin in the primary prevention of stroke and CVD-related death.

C-reactive protein and other markers of inflammation in the prediction of cardiovascular disease in women

BACKGROUND

Since inflammation is believed to have a role in the pathogenesis of cardiovascular events, measurement of markers of inflammation has been proposed as a method to improve the prediction of the risk of these events.

METHODS

We conducted a prospective, nested case-control study among 28,263 apparently healthy postmenopausal women over a mean follow-up period of three years to assess the risk of cardiovascular events associated with base-line levels of markers of inflammation. The markers included high-sensitivity C-reactive protein (hs-CRP), serum amyloid A, interleukin-6, and soluble intercellular adhesion molecule type 1 (sICAM-1). We also studied homocysteine and a variety of lipid and lipoprotein measurements. Cardiovascular events were defined as death from coronary heart disease, nonfatal myocardial infarction or stroke, or the need for coronary-revascularization procedures.

RESULTS

Of the 12 markers measured, hs-CRP was the strongest univariate predictor of the risk of cardiovascular events; the relative risk of events for women in the highest as compared with the lowest quartile for this marker was 4.4 (95 percent confidence interval, 2.2 to 8.9). Other markers significantly associated with the risk of cardiovascular events were serum amyloid A (relative risk for the highest as compared with the lowest quartile, 3.0), sICAM-1 (2.6), interleukin-6 (2.2), homocysteine (2.0), total cholesterol (2.4), LDL cholesterol (2.4), apolipoprotein B-100 (3.4), HDL cholesterol (0.3), and the ratio of total cholesterol to HDL cholesterol (3.4). Prediction models that incorporated markers of inflammation in addition to lipids were significantly better at predicting risk than models based on lipid levels alone (P<0.001). The levels of hs-CRP and serum amyloid A were significant predictors of risk even in the subgroup of women with LDL cholesterol levels below 130 mg per deciliter (3.4 mmol per liter), the target for primary prevention established by the National Cholesterol Education Program. In multivariate analyses, the only plasma markers that independently predicted risk were hs-CRP (relative risk for the highest as compared with the lowest quartile, 1.5; 95 percent confidence interval, 1.1 to 2.1) and the ratio of total cholesterol to HDL cholesterol (relative risk, 1.4; 95 percent confidence interval, 1.1 to 1.9).

CONCLUSIONS

The addition of the measurement of C-reactive protein to screening based on lipid levels may provide an improved method of identifying persons at risk for cardiovascular events.

Blood levels of homocysteine and increased risks of cardiovascular disease: causal or casual?

BACKGROUND

Accumulating data from epidemiological studies suggest that individuals with elevated blood levels of homocysteine have increased risks of cardiovascular disease. We reviewed the currently available evidence of an association between homocysteine and cardiovascular disease and examined whether the strength of the evidence varies according to study design.

METHODS

We used a computerized MEDLINE literature search, 1966 through September 1998, to identify all epidemiological studies that examined the relationship of homocysteine level with risks of coronary heart or cerebrovascular disease. Two measures of plasma homocysteine level and its association with risk of cardiovascular disease were extracted: mean homocysteine level in cases and controls, and relative risk of cardiovascular disease for elevated homocysteine level.

RESULTS

A total of 43 studies were reviewed. Most crosssectional and case-control studies indicated higher mean homocysteine levels (either fasting or after methionine load) and/or a greater frequency of elevated homocysteine level in persons with cardiovascular disease as compared with persons without cardiovascular disease. Results of most prospective studies, however, indicated smaller or no association. The few prospective studies that reported a positive association between homocysteine level and risks of cardiovascular disease included patients with preexisting vascular disease.

CONCLUSIONS

In contrast to cross-sectional and case-control studies, results of prospective studies indicated less or no predictive ability for plasma homocysteine in cardiovascular disease. Instead, elevated homocysteine level may be an acute-phase reactant that is predominantly a marker of atherogenesis, or a consequence of other factors more closely linked to risks of cardiovascular disease. Randomized trials are necessary to test reliably whether lowering homocysteine levels will decrease risks of cardiovascular disease.

A prospective study of physical activity and risk of prostate cancer in US physicians

BACKGROUND

Exercise can suppress androgen production and may thus decrease the risk of prostate cancer. However, findings from epidemiological studies assessing physical activity and risk of prostate cancer are inconsistent.

METHODS

We prospectively examined the association between physical activity and prostate cancer risk in the Physicians' Health Study (PHS), a randomized trial of low-dose aspirin and beta-carotene among 22,071 men aged 40-84 without self-reported myocardial infarction, stroke and cancer. At baseline in 1982, men were asked about the frequency of exercise vigorous enough to work up a sweat. Physical activity was assessed in a similar fashion again at 36 months of follow-up.

RESULTS

During 11.1 years of follow-up (258 779 person-years), 982 cases of prostate cancer occurred and were confirmed by medical record review. After adjustment for potential confounding factors (including age, height, randomized treatment assignment, smoking status, alcohol intake, use of multivitamins, history of diabetes, history of hypertension and history of high cholesterol), the relative risks for prostate cancer associated with exercise vigorous enough to work up a sweat were 1.0 (referent) for frequency less than once per week, 1.02 (95% CI: 0.82-1.26) for once per week, 1.07 (95% CI: 0.90-1.27) for 2-4 times per week, and 1.11 (95% CI: 0.90-1.36) for 5+ times per week. Across all subgroups of men categorized by age, body mass index, smoking status, alcohol intake, use of multivitamins, history of diabetes, history of hypertension and history of high cholesterol, there were no significant associations between frequency of exercise vigorous enough to work up a sweat and prostate cancer risk. After excluding cases of prostate cancer that occurred during the first 36 months of follow-up, again, there was no significant association. Combining physical activity assessments at baseline and at 36 months also yielded no significant association with prostate cancer risk.

CONCLUSIONS

These observational data from the Physicians' Health Study do not support the hypothesis that increased physical activity reduces the risk of prostate cancer.