Biomedical subjects

Lloyd E Chambless

Publications and source records attributed to Lloyd E Chambless.

At least 37 records · Page 2Linked to original sources

PubMed2004

Trends in the sensitivity, positive predictive value, false-positive rate, and comparability ratio of hospital discharge diagnosis codes for acute myocardial infarction in four US communities, 1987-2000.

Variations in the validity of hospital discharge diagnoses can complicate the assessment of trends in incidence of acute myocardial infarction (AMI). To clarify trends in the validity of discharge codes, the authors compared event classification based on published Atherosclerosis Risk in Communities (ARIC) Study criteria with the presence or absence of an International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) hospital discharge code for AMI (code 410). Between 1987 and 2000, 154,836 coronary heart disease events involving hospitalization in the four ARIC communities had ICD-9-CM codes screened for AMI. The sensitivity of ICD-9-CM code 410 for classifying AMI in men (sensitivity = 0.65, 95% confidence interval (CI): 0.63, 0.66) was statistically significantly greater than that found for women (sensitivity = 0.60, 95% CI: 0.58, 0.62) and was greater in Whites (sensitivity = 0.67, 95% CI: 0.65, 0.68) than in Blacks (sensitivity = 0.50, 95% CI: 0.47, 0.53). The ethnic difference was related to a greater frequency of hypertensive heart disease and congestive heart failure codes encompassing AMI among Blacks as compared with Whites. The authors found that although the validity of ICD-9-CM code 410 to identify AMI was generally stable from 1987 through 2000, differences between Blacks and Whites and across geographic locations support investment in validation efforts in ongoing surveillance studies.

Adult↗

PubMed2004

Association between alcoholic beverage consumption and incidence of coronary heart disease in whites and blacks: the Atherosclerosis Risk in Communities Study.

The authors evaluated the relation between consumption of alcoholic beverages and incidence of coronary heart disease in White and African-American participants in the Atherosclerosis Risk in Communities Study. The average duration of follow-up was 9.8 years between 1987 and 1998. The association was analyzed by means of Cox proportional hazards regression models. The authors found a positive association between ethanol consumption and incident coronary heart disease for Black men (for a 13-g/day increment in ethanol consumption, adjusted hazard ratio (HR) = 1.13, 95% confidence interval (CI): 1.01, 1.28) and an inverse association for White men (HR = 0.88, 95% CI: 0.79, 0.99). There was an inverse association of coronary heart disease with rare drinking (HR = 0.47, 95% CI: 0.28, 0.80) and with consumption of > or =70 g of ethanol per week (HR = 0.49, 95% CI: 0.24, 0.98) in White women and with consumption of > or =210 g/week (HR = 0.56, 95% CI: 0.33, 0.95) in White men. In Black men, the association was positive for consumption of 140-<210 g/week (HR = 2.61, 95% CI: 1.11, 6.17). The contrasting findings in Whites and Black men in this cohort raise the question of whether the cardioprotective effect of alcohol is real or may be confounded by lifestyle characteristics of drinkers.

Black People↗

PubMed2004

Prediction of ischemic stroke risk in the Atherosclerosis Risk in Communities Study.

The authors assessed the increase in the predictivity of ischemic stroke (IS) resulting from the addition of nontraditional risk factors and markers of subclinical disease to a basic model containing only traditional risk factors (current smoking, diabetes mellitus, systolic blood pressure, antihypertensive therapy, prior coronary disease, and left ventricular hypertrophy) among 14,685 middle-aged persons in the Atherosclerosis Risk in Communities Study. Participants were recruited from four US communities in 1987-1989. Risk prediction scores for IS through 2000 were estimated from Cox models. The ability to predict which persons would develop IS was assessed by means of the area under the receiver operating characteristic curve-the probability that persons with IS had a higher risk score than those without IS. Among 22 nontraditional factors considered, the joint addition of body mass index, waist:hip ratio, high density lipoprotein cholesterol, albumin, von Willebrand factor, alcohol consumption, peripheral arterial disease, and carotid artery wall thickness modestly and statistically significantly improved prediction of future IS over a risk score that included traditional factors. Further improvement was obtained by adding age and race. For women, the area under the receiver operating characteristic curve went from 0.79 to 0.83 to 0.84; for men, it went from 0.76 to 0.78 to 0.80. These modest improvements are not enough to influence clinical and public health efforts to reduce the community burden of IS.

Antihypertensive Agents↗

PubMed2004

Lowering homocysteine in patients with ischemic stroke to prevent recurrent stroke, myocardial infarction, and death: the Vitamin Intervention for Stroke Prevention (VISP) randomized controlled trial.

CONTEXT: In observational studies, elevated plasma total homocysteine levels have been positively associated with ischemic stroke risk. However the utility of homocysteine-lowering therapy to reduce that risk has not been confirmed by randomized trials. OBJECTIVE: To determine whether high doses of folic acid, pyridoxine (vitamin B6), and cobalamin (vitamin B12), given to lower total homocysteine levels, reduce the risk of recurrent stroke over a 2-year period compared with low doses of these vitamins. DESIGN: Double-blind randomized controlled trial (September 1996-May 2003). SETTING AND PARTICIPANTS: 3680 adults with nondisabling cerebral infarction at 56 university-affiliated hospitals, community hospitals, private neurology practices, and Veterans Affairs medical centers across the United States, Canada, and Scotland. INTERVENTIONS: All participants received best medical and surgical care plus a daily multivitamin containing the US Food and Drug Administration's reference daily intakes of other vitamins; patients were randomly assigned to receive once-daily doses of the high-dose formulation (n = 1827), containing 25 mg of pyridoxine, 0.4 mg of cobalamin, and 2.5 mg of folic acid; or the low-dose formulation (n = 1853), containing 200 microg of pyridoxine, 6 microg of cobalamin and 20 microg of folic acid. MAIN OUTCOME MEASURES: Recurrent cerebral infarction (primary outcome); coronary heart disease (CHD) events and death (secondary outcomes). RESULTS: Mean reduction of total homocysteine was 2 micromol/L greater in the high-dose group than in the low-dose group, but there was no treatment effect on any end point. The unadjusted risk ratio for any stroke, CHD event, or death was 1.0 (95% confidence interval [CI], 0.8-1.1), with chances of an event within 2 years of 18.0% in the high-dose group and 18.6% in the low-dose group. The risk of ischemic stroke within 2 years was 9.2% for the high-dose and 8.8% for the low-dose groups (risk ratio, 1.0; 95% CI, 0.8-1.3) (P =.80 by log-rank test of the primary hypothesis of difference in ischemic stroke between treatment groups). There was a persistent and graded association between baseline total homocysteine level and outcomes. A 3- micromol/L lower total homocysteine level was associated with a 10% lower risk of stroke (P =.05), a 26% lower risk of CHD events (P<.001), and a 16% lower risk of death (P =.001) in the low-dose group and a nonsignificantly lower risk in the high-dose group by 2% for stroke, 7% for CHD events, and 7% for death. CONCLUSIONS: In this trial, moderate reduction of total homocysteine after nondisabling cerebral infarction had no effect on vascular outcomes during the 2 years of follow-up. However, the consistent findings of an association of total homocysteine with vascular risk suggests that further exploration of the hypothesis is warranted and longer trials in different populations with elevated total homocysteine may be necessary.

Adult↗

PubMed2004

Synergism between smoking and vital exhaustion in the risk of ischemic stroke: evidence from the ARIC study.

PURPOSE: To examine the synergism between vital exhaustion and cigarette smoking in producing ischemic stroke. Vital exhaustion (VE), a state characterized by unusual fatigue, irritability, and feelings of demoralization, is measured by the Maastricht questionnaire (MQ), a 21-item inventory of symptoms. METHODS: The Atherosclerosis Risk in Communities (ARIC) Study is an ongoing cohort study, initiated in 1987. The MQ was administered at the second follow-up visit (1990-1992), and participants were subsequently followed for an average of 6.27 years. Four US communities (Minneapolis, Minnesota; Washington County, Maryland; Forsyth County, North Carolina; and Jackson, Mississippi). 13,066 participants aged 48 to 67 years at baseline (Visit 2) with no history of stroke. Validated hospitalized ischemic stroke. RESULTS: During the follow-up period, there were 202 incident ischemic strokes. After multivariate adjustment, current smoking, and high VE were independent risk factors for incident stroke: (smoking vs. non-smoking HR=1.76, p < 0.01; high VE vs. low VE HR=1.94, p < 0.01). For persons with both VE and smoking vs. persons with neither, HR=2.71 (p < 0.001). The proportion of stroke disease burden due to VE and smoking that could be attributed to their interaction was 81 to 93 percent. CONCLUSIONS: The combination of cigarette smoking and VE is synergistic in the production of stroke.

Aged↗

PubMed2004

Repeatability of heart rate variability measures.

Due to the sparse data on the repeatability of short and ultra-short term heart rate variability (HRV) measures, we measured the repeatability of common HRV measures derived from 10-second, 2-minute, and 6-minute recordings in 63 healthy men and women, aged 45-64, in Chapel Hill, North Carolina. Three 10-second and 2 six-minute heart rate recordings were obtained during each of 2 visits, separated by 1 to 2 weeks. We partitioned the measurement error into components and computed intraclass correlation coefficients using nested, random effects models. Repeatability improved with the length of recording: intraclass correlation coefficients were greater than 0.7 for 6-minute measures and 2-minute time domain measures and greater than 0.5 for 2-minute frequency domain measures. Repeatability of measures from 10-second records was lower, but improved considerably when the mean from 2 or 3 records was used. Correlations between the same measures from different length recordings were quite high. Our findings support the use of records of at least 5 minutes in length in epidemiological studies, in accordance with previous guidelines. Researchers using 10-second records should consider taking the mean of several recordings, when possible, or using statistical methods to correct for measurement error.

Electrocardiography↗

PubMed2003

Risk factors for progression to incident hyperinsulinemia: the Atherosclerosis Risk in Communities Study, 1987-1998.

Hyperinsulinemia is a marker of insulin resistance, a correlate of the metabolic syndrome, and an established precursor of type 2 diabetes. This US study investigated the role of risk factors associated with hyperinsulinemia in cross-sectional studies in progression to incident hyperinsulinemia. Nondiabetic participants from the Atherosclerosis Risk in Communities Study (n = 9,020) were followed from 1987 to 1998 for the development of hyperinsulinemia (fasting serum insulin > or = 90th percentile, 19.1 micro U/ml). After adjustment for demographic characteristics, all risk factors simultaneously, and baseline insulin value, the risk of progressing to hyperinsulinemia increased per standard deviation increase in baseline uric acid (odds ratio (OR) = 1.3, 95% confidence interval (CI): 1.2, 1.4; per 1.4 mg/dl) and waist/hip ratio (OR = 1.4, 95% CI: 1.2, 1.5; per 0.08) and was inversely associated with high density lipoprotein cholesterol (OR = 0.8, 95% CI: 0.7, 0.9; per 0.4 mmol/liter). Starting to smoke (OR = 1.5, 95% CI: 1.2, 2.0) and becoming obese (OR = 2.4, 95% CI: 1.8, 3.1) during the study were also associated with increased risk. The associations were similar across race and gender groups. These data suggest that, in addition to weight gain, hyperuricemia, dyslipidemia, and smoking can be detected prior to development of hyperinsulinemia.

Arteriosclerosis↗

PubMed2003

Hypertension, blood pressure, and heart rate variability: the Atherosclerosis Risk in Communities (ARIC) study.

Dysregulation of the autonomic nervous system has been implicated in the development of hypertension. Heart rate variability is a noninvasive tool to quantitatively estimate cardiac autonomic activity and has been used to document decreased cardiac autonomic activity in hypertension. The ability of decreased heart rate variability to predict incident hypertension has not been well studied, and there are no studies of whether hypertension leads to changes in heart rate variability. We investigated the temporal sequence linking hypertension, blood pressure, and heart rate variability in a population-based cohort of 11 061 individuals aged 45 to 54 years at baseline. Individuals with hypertension had decreased heart rate variability at baseline, and this association was present across the full blood pressure range. Among 7099 individuals without hypertension at baseline, low heart rate variability predicted greater risk of incident hypertension over 9 years of follow-up. The hazard ratio (95% confidence interval [CI]) for the lowest compared with the highest quartile of the standard deviation of normal-to-normal R-R intervals was 1.24 (95% CI, 1.10-1.40), for the root mean square of successive differences in normal-to-normal R-R intervals was 1.36 (95% CI, 1.21-1.54), and for R-R interval was 1.44 (95% CI, 1.27-1.63). Over 9 years, there was no measurable difference in the rate of change in heart rate variability among those with and without hypertension, although the differences in heart rate variability at follow-up were smaller than those at baseline. These findings thus support the thesis that the autonomic nervous system is involved in the development of hypertension, yet suggest that differences in the autonomic profile of hypertensives and normotensives do not increase with time.

Blood Pressure↗

PubMed2003

Analysis of associations with change in a multivariate outcome variable when baseline is subject to measurement error.

A simple general algorithm is described for correcting for bias caused by measurement error in independent variables in multivariate linear regression. This algorithm, using standard software, is then applied to several approaches to the analysis of change from baseline as a function of baseline value of the outcome measure plus other covariates, any of which might have measurement error. The algorithm may also be used when the independent variables differ by component of the multivariate independent variable. Simulations indicate that under various conditions bias is much reduced, as is mean squared error, and coverage of 95 per cent confidence intervals is good.

Algorithms↗

PubMed2003

Plasma lipid profile and incident ischemic stroke: the Atherosclerosis Risk in Communities (ARIC) study.

BACKGROUND AND PURPOSE: The role of circulating lipids and lipoproteins in the pathogenesis of ischemic stroke remains uncertain despite 3 decades of research. We examined this issue in a large population-based cohort. METHODS: Between 1987 and 1989, 14 175 middle-aged men and women, free of clinical cardiovascular disease, took part in the first examination of the Atherosclerosis Risk in Communities (ARIC) study cohort. Baseline measurements included plasma levels of LDL cholesterol, HDL cholesterol, apolipoprotein B, apolipoprotein A-1, and triglycerides and myriad risk factors for cardiovascular disease. The cohort was followed for cardiovascular disease end points. RESULTS: Over an average follow-up of 10 years (142 704 person-years at risk), we documented clinical ischemic stroke in 305 participants (161 men and 144 women). After multivariable adjustment for stroke risk factors, categorical and spline regression analyses of the entire sample, as well as the sample of men alone, revealed weak and inconsistent associations between ischemic stroke and each of the 5 lipid factors. Among women, the most consistent findings were decreasing risk of ischemic stroke within the top half of the distribution of HDL cholesterol and increasing risk within the lower range of the triglyceride distribution. CONCLUSIONS: The relation of circulating cholesterol to ischemic stroke does not resemble its well-known relation to coronary heart disease. Either the pathogenesis of a substantial proportion of ischemic strokes does not involve classic atherosclerotic mechanisms, or the effect of plasma lipids on atherogenesis is substantially different in the intracranial vascular bed.

Apolipoprotein A-I↗

PubMed2003

B vitamin status and inflammatory markers.

Limited evidence has suggested that low levels of circulating pyridoxal-5'-phosphate (PLP) may be associated with elevation of the inflammatory marker, C-reactive protein (CRP). We sought to determine whether the reported association of CRP with PLP was specific versus generalizable to other inflammation or hemostasis markers. Among 519 healthy middle aged adults in the Atherosclerosis Risk in Communities (ARIC) Study, we analyzed the cross-sectional relation of homocysteine, plasma and dietary B vitamin levels with multiple markers implicated in inflammation, endothelial dysfunction, or thrombogenesis: CRP, fibrinogen, white blood cell count, intracellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1), E-selectin, factor VIII, and von Willebrand factor. There was no significant association (P>0.05) of von Willebrand factor, I-CAM, or V-CAM with any of the plasma or dietary measures examined, and no marker was associated significantly with serum homocysteine. Contrary to our hypothesis, plasma PLP was not associated with CRP concentration. A higher white blood cell count was associated with lower B vitamin status (lower plasma PLP and folate, lower dietary B6 and B12), though not with use of vitamin supplements. In ostensibly healthy adults, B-vitamin status is not a strong correlate of circulating levels of inflammatory markers, cellular adhesion molecules, or thrombogenic factors.

Arteriosclerosis↗

PubMed2003

Coronary heart disease risk prediction in the Atherosclerosis Risk in Communities (ARIC) study.

Risk prediction functions for incident coronary heart disease (CHD) were estimated using data from the Atherosclerosis Risk in Communities (ARIC) Study, a prospective study of CHD in 15,792 persons recruited in 1987-1989 from four U.S. communities, with follow-up through 1998. Predictivity of which individuals had incident CHD was assessed by increase in area under ROC curves resulting from adding nontraditional risk factors and markers of subclinical disease to a basic model containing only traditional risk factors. We also assessed the increase in population attributable risk. The additional factors were body mass index; waist-hip ratio; sport activity index; forced expiratory volume; plasma fibrinogen, factor VIII, von Willebrand factor, and Lp(a); heart rate; Keys score; pack-years smoking; and subclinical disease marker carotid intima-media thickness. These factors substantially improved prediction of future CHD for men, less for women, and also increased attributable risks.

Age Factors↗

PubMed2003

Inflammation markers predict increased weight gain in smoking quitters.

OBJECTIVE: Undesirable weight gain often follows smoking cessation. We investigated whether weight gain after smoking cessation is greater in those with higher levels of inflammatory markers. RESEARCH METHODS AND PROCEDURES: We studied weight gain and risk of a large gain (> or = 90th percentile) over 3 years in a cohort study of 11,687 U.S. men and women, 45 to 64 years old, with focus on the 2664 who continued and the 493 who quit smoking. RESULTS: Among new quitters, adjusted weight gain for those in the highest (vs. lowest) quartile of leukocytes was 0.56 kg/yr more (95% confidence interval, 0.17 to 0.95); for those in the highest (vs. lowest) quartile of fibrinogen, 0.60 kg/yr more (95% confidence interval, 0.27 to 0.92; p = 0.02 and 0.001 for adjusted smoking status by leukocyte and smoking status by fibrinogen interaction terms, respectively). In adjusted analyses, the odds ratio for a large gain associated with quitting (vs. continuing) was 6.2 for those in the highest quartile of leukocytes vs. 2.2 for those in the lowest leukocyte quartile (p = 0.03 for smoking status by inflammatory marker interaction). Similarly, the odds ratio for a large gain associated with quitting was 4.5 in the highest fibrinogen quartile vs. 2.5 in the lowest (p = 0. 09 for the interaction term). DISCUSSION: Weight gain after smoking cessation is increased in those with higher baseline levels of leukocytes and fibrinogen. These findings suggest a close relationship between inflammatory mediators and regulators of energy balance that may have important clinical implications.

Biomarkers↗

PubMed2003

Prediction of coronary heart disease in middle-aged adults with diabetes.

OBJECTIVE: To determine the 10-year probability of coronary heart disease (CHD) in diabetic adults and how well basic and novel risk factors predict CHD risk. RESEARCH DESIGN AND METHODS: We measured risk factors in 14054 participants (1500 with diabetes) initially free of CHD in the Atherosclerosis Risk in Communities study from 1987 to 1989 and followed them prospectively for CHD incidence through 1998. We used proportional hazards regression models and receiver operating characteristic (ROC) curves for CHD risk prediction. RESULTS: Based on our model using basic risk factors (age, race, total and HDL cholesterol, systolic blood pressure, antihypertensives, and smoking status), approximately 61% of diabetic women and 86% of diabetic men had a predicted 10-year CHD probability >or=10%. This CHD risk-prediction model had an area under the ROC curve of 0.72 in diabetic women and 0.67 in diabetic men. Novel risk factors or subclinical disease markers individually added only modest predictivity, but the addition of multiple markers (BMI, waist-to-hip ratio, Keys dietary score, serum albumin and creatinine, factor VIII, white blood cell count, left ventricular hypertrophy determined by electrocardiogram, and carotid intima-media thickness) increased the area under the curve by approximately 10%. CONCLUSIONS: Although all diabetic adults are at high risk for CHD, their variation in CHD risk can be predicted moderately well by basic risk factors. No single novel risk marker greatly enhanced absolute CHD risk assessment, but a battery of novel markers did. Our model can provide estimates of CHD risk for the primary prevention of this disease in people with type 2 diabetes.

Coronary Disease↗

PubMed2003

Risk of atherosclerosis: interaction of smoking and glutathione S-transferase genes.

BACKGROUND: Cigarette smoking is a well-known risk factor for not only incident events of coronary heart disease, but also preclinical atherosclerosis. Enzymes including glutathione S-transferase mu (GSTM1) and theta (GSTT1) are involved in the metabolism of tobacco smoke chemicals and are expressed in human vessels and smooth muscle cells. METHODS: We estimated the effect of interaction of smoking with the deletion polymorphisms of GSTM1 and GSTT1 on the risk of carotid artery atherosclerosis. We analyzed a stratified random sample of 1394 individuals from the Atherosclerosis Risk in Communities (ARIC) study, which is a prospective cohort study of 15,792 white and black men and women randomly selected from four U.S. communities between 1987 and 1989. As an index of generalized atherosclerosis, we used carotid artery intimal-medial thickness, as determined by B-mode ultrasound at the baseline or first follow-up examination in asymptomatic individuals. RESULTS: We found a suggestion of an interaction between the functional GSTT-1 genotype (GSTT-1) and heavy smoking. For 20 or more pack-years and GSTT1-1, the odds ratio for increased intimal-medial thickness was 4.7 (95% confidence interval = 1.9-11.8); for 20 or more pack-years and GSTT1-0, 1.7 (0.5-5.5); and for nonsmokers and GSTT1-1, 0.7 (0.3-1.5). We found no interaction between smoking and GSTM1. CONCLUSIONS: The results of this analysis of preclinical atherosclerosis extend reports from the ARIC study of an interaction between smoking and GSTT1-1 in relation to the risk of incident coronary heart disease and lower extremity arterial disease.

Arteriosclerosis↗

PubMed2002

Occurrence of unrecognized myocardial infarction in subjects aged 45 to 65 years (the ARIC study).

Previous observational studies conducted predominantly in white men before 1988 estimated that 20% to 40% of myocardial infarctions (MIs) are unrecognized. Recent data on the proportion of MIs that are unrecognized, especially in women and African-Americans, are largely unavailable. Participants in the Atherosclerosis Risk in Communities (ARIC) study were men and women, aged 45 to 65 years, who were free of clinically recognized coronary heart disease and electrocardiographic evidence of MI at baseline (n = 12,843). Three follow-up clinic examinations were conducted approximately 3, 6, and 9 years after baseline, and included a 12-lead electrocardiogram at rest. Electrocardiographic evidence of infarction was defined as the appearance between the baseline and subsequent examinations of a major Q wave or a minor Q wave with ischemic ST-T changes. Clinically recognized (hospitalized) MI events were also identified and validated. Incident unrecognized MI was defined as electrocardiographic evidence of MI before, or in the absence of, a clinically recognized MI during the follow-up period. Of 508 MIs, 20% were unrecognized (95% confidence interval 16% to 23%), with African-Americans having a slightly higher percentage (23%) than whites (19%). The percentage of unrecognized MIs in men and women was similar. The percentage of unrecognized MIs in the ARIC sample between 1987 and 1998 was slightly lower than previous estimates from other populations.

Aged↗

PubMed2002

Risk factors for progression of common carotid atherosclerosis: the Atherosclerosis Risk in Communities Study, 1987-1998.

Intima-media thickness of the common carotid arteries is a marker of atherosclerosis and has been shown to be associated with prevalent and incident coronary heart disease and with coronary heart disease risk factors. The authors examined the association of baseline risk factors or change in risk factors with change in intima-media thickness over follow-up (1987-1998) in the Atherosclerosis Risk in Communities (ARIC) population-based cohort (baseline: age 45-64 years, n = 15,792). Subjects were members of households sampled in four areas of the United States. Either not adjusting for baseline intima-media thickness or doing so with correction for its measurement error resulted in statistically significant associations of change in intima-media thickness with baseline diabetes, current smoking, high density lipoprotein cholesterol, pulse pressure, white blood cell count, and fibrinogen. The associations were of a similar order of magnitude as anticipated from the authors' cross-sectional findings. Statistically significant associations were found between change in intima-media thickness and change in low density lipoprotein cholesterol and triglycerides and with onset of diabetes and hypertension. In summary, established risk factors for coronary heart disease are associated with the rate of change of subclinical atherosclerosis.

Carotid Artery Diseases↗

PubMed2002

Does the cardiac autonomic response to postural change predict incident coronary heart disease and mortality? The Atherosclerosis Risk in Communities Study.

This study evaluated whether small shifts in cardiac autonomic balance with standing, as measured by heart rate variability (HRV), were prospectively associated with incident coronary heart disease (CHD) and mortality. Both Black and White men and women aged 45-64 years from the Atherosclerosis Risk in Communities Study (n = 9,267) were followed from 1987 to 1997 for myocardial infarction (n = 296), fatal CHD (n = 63), and non-CHD mortality (n = 533). HRV indices and mean R-R interval length (inverse of heart rate) were measured in the supine and standing positions for 2 minutes each; HRV shift was calculated as the difference between positions. After adjustment for demographic characteristics and medication use, HRV in each position was significantly inversely related to events in Cox proportional hazards models. With the exception of R-R interval length shift and myocardial infarction (hazard ratio = 1.42, 95% confidence interval: 1.02, 1.98 for the smallest vs. the largest quartile), there was no association between HRV shift and the other events. Despite clinical research suggesting that HRV shift with standing is a more sensitive measure of autonomic balance than is HRV in one position, simple measures such as heart rate change and supine and standing HRV were better predictors of events.

Autonomic Nervous System↗