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Biomedical subjects

L E Chambless

Publications and source records attributed to L E Chambless.

At least 55 records · Page 3Linked to original sources
PubMed1998

Trends in the incidence of myocardial infarction and in mortality due to coronary heart disease, 1987 to 1994.

BACKGROUND AND METHODS: To clarify the determinants of contemporary trends in mortality from coronary heart disease (CHD), we conducted surveillance of hospital admissions for myocardial infarction and of in-hospital and out-of-hospital deaths due to CHD among 35-to-74-year-old residents of four communities of varying size in the United States (a total of 352,481 persons in 1994). Between 1987 and 1994, we estimate that there were 11,869 hospitalizations for myocardial infarction (on the basis of 8572 hospitalizations sampled) and 3407 fatal coronary events (3023 sampled). RESULTS: The largest average annual decrease in mortality due to CHD occurred among white men (change in mortality, -4.7 percent; 95 percent confidence interval, -2.2 to -7.1 percent), followed by white women (-4.5 percent; 95 percent confidence interval, -0.7 to -8.2 percent), black women (-4.1 percent; 95 percent confidence interval, -10.3 to +2.5 percent), and black men (-2.5 percent; 95 percent confidence interval, -6.9 to +2.2 percent). Overall, in-hospital mortality from CHD fell by 5.1 percent per year, whereas out-of-hospital mortality declined by 3.6 percent per year. There was no evidence of a decline in the incidence of hospitalization for a first myocardial infarction among either men or women; in fact, such hospital admissions increased by 7.4 percent per year (95 percent confidence interval for the change, +0.5 to +14.8 percent) among black women and 2.9 percent per year (95 percent confidence interval, -3.6 to +9.9 percent) among black men. Rates of recurrent myocardial infarction decreased, and survival after myocardial infarction improved. CONCLUSIONS: From 1987 to 1994, we observed a stable or slightly increasing incidence of hospitalization for myocardial infarction. Nevertheless, there were significant annual decreases in mortality from CHD. The decline in mortality in the four communities we studied may be due largely to improvements in the treatment and secondary prevention of myocardial infarction.

Adult↗
PubMed1998

Helicobacter pylori seropositivity and coronary heart disease incidence. Atherosclerosis Risk In Communities (ARIC) Study Investigators.

BACKGROUND: Several epidemiological and clinical reports have suggested seropositivity for Helicobacter pylori may be a risk factor for coronary heart disease. However, there has been no prospective study of this association involving an ethnically diverse sample of middle-aged men and women. METHODS AND RESULTS: Using a prospective, case-cohort design, we determined H pylori seropositivity in relation to coronary heart disease incidence over a median follow-up period of 3.3 years among middle-aged men and women. There were 217 incident coronary heart disease cases and a cohort sample of 498. We determined H pylori antibody status by measuring IgG antibody to the high-molecular-weight cell-associated proteins of H pylori using a sensitive and specific ELISA. The prevalence of H pylori seropositivity was higher in blacks than whites, in those with less than high school education, in those with lower plasma pyridoxal 5'-phosphate and higher homocyst(e)ine concentrations, in those who did not use vitamin supplements, in those with higher fibrinogen levels, and in those seropositive for cytomegalovirus and herpes simplex type I (all P<0.05). The age-, sex-, race-, and field center-adjusted hazard ratio of coronary heart disease for H pylori seropositivity was 1.03 (95% CI=0.68 to 1.57). After adjustment for other risk factors, including fibrinogen, cytomegalovirus seropositivity, and herpes simplex type I seropositivity, the hazard ratio was 0.85 (95% CI=0.43 to 1.69). H pylori seropositivity also was not associated with increased mean intima-media thickness of the carotid artery, a measure of subclinical atherosclerosis. CONCLUSIONS: H pylori infection is probably not an important contributor to clinical coronary heart disease events.

Antibodies, Bacterial↗
PubMed1998

Body weight change and carotid artery wall thickness. The Atherosclerosis Risk in Communities (ARIC) Study.

The impact of weight change in adulthood on cardiovascular disease is controversial. This study examined the association of change in body weight, from young adulthood to middle age, with average carotid artery intimal-medial wall thickness by B-mode ultrasound measured in middle age. Participants were 13,282 men and women aged 45-64 years from the baseline examination of the Atherosclerosis Risk in Communities (ARIC) Study (1987-1989). Weight change was calculated as the difference between weight at the baseline examination and self-reported weight at age 25. White men gained a mean of 9.7 kg; black men, 10.1 kg; white women, 12.0 kg; and black women, 20.8 kg. Weight change was positively, albeit modestly, associated with intimal-medial thickness in black men and white men and in white women, but not in black women. Adjusted for age, examination center, smoking, education, sports activity level, height, and body mass index at age 25, the differences in intimal-medial thickness associated with a 10-kg increment in weight change were 0.016 (95% confidence interval 0.010 to 0.022) mm in white men, 0.008 (95% confidence interval 0.001 to 0.015) mm in black men, 0.013 (95% confidence interval 0.009 to 0.017) mm in white women, and 0.002 (95% confidence interval -0.002 to 0.006) mm in black women. These findings support the hypothesis that weight gain in adulthood promotes atherosclerotic changes in white men and women and in black men.

Arteriosclerosis↗
PubMed1997

Assessing differences in clinical trials comparing surgical vs nonsurgical therapy: using common (statistical) sense.

The statement of hypotheses and choice of statistical tests in clinical trials that compare surgical with nonsurgical treatment are complicated by the likelihood of excess risk in the surgical group during the perioperative period but lower risk after that compared with the more uniform risk in the nonsurgical group. Commonly used statistical survival analyses implicitly assume a constant ratio of risks in the 2 groups during the follow-up period. However, the changing pattern of risk for one treatment but not the other implies that the assessment of the relative efficacy of the treatments varies with the length of the follow-up. As such, determining whether survival curves for the 2 groups are different may not translate easily into selecting the best treatment. Alternative statements of the hypothesis based on consideration of the time horizon of patients and on clinical judgment may be more consistent with the goals of the study. Regardless of the choice of a statistical test, the choice of treatment is a decision specific to the individual patient and should be influenced by the patient's life expectancy, attitude toward taking risks, quality of life, and cost considerations. When the survival curves cross, there is a trade-off between the risk of surgery and the increase in life expectancy among the survivors of surgery. Accordingly, assessment of differences in outcomes in clinical trials comparing surgical vs nonsurgical therapy should provide both a conclusion about whether 1 treatment can reasonably be considered best for most patients and should provide information to the individual patient and physician on the expected outcome to aid in the decision-making process.

Clinical Medicine↗
PubMed1997

Association of coronary heart disease incidence with carotid arterial wall thickness and major risk factors: the Atherosclerosis Risk in Communities (ARIC) Study, 1987-1993.

Few studies have determined whether greater carotid artery intima-media thickness (IMT) in asymptomatic individuals is associated prospectively with increased risk of coronary heart disease (CHD). In the Atherosclerosis Risk in Communities Study, carotid IMT, an index of generalized atherosclerosis, was defined as the mean of IMT measurements at six sites of the carotid arteries using B-mode ultrasound. The authors assessed its relation to CHD incidence over 4-7 years of follow-up (1987-1993) in four US communities (Forsyth County, North Carolina; Jackson, Mississippi; Minneapolis, Minnesota; and Washington County, Maryland) from samples of 7,289 women and 5,552 men aged 45-64 years who were free of clinical CHD at baseline. There were 96 incident events for women and 194 for men. In sex-specific Cox proportional hazards models adjusted only for age, race, and center, the hazard rate ratio comparing extreme mean IMT (> or = 1 mm) to not extreme (< 1 mm) was 5.07 for women (95% confidence interval 3.08-8.36) and 1.85 for men (95% confidence interval 1.28-2.69). The relation was graded (monotonic), and models with cubic splines indicated significant nonlinearity. The strength of the association was reduced by including major CHD risk factors, but remained elevated at higher IMT. Up to 1 mm mean IMT, women had lower adjusted annual event rates than did men, but above 1 mm their event rate was closer to that of men. Thus, mean carotid IMT is a noninvasive predictor of future CHD incidence.

Age Distribution↗
PubMed1997

Prospective study of hemostatic factors and incidence of coronary heart disease: the Atherosclerosis Risk in Communities (ARIC) Study.

BACKGROUND: Although hemostatic factors contribute to acute coronary syndromes and atherogenesis, few studies have prospectively evaluated the association between multiple hemostatic factors and coronary heart disease incidence. METHODS AND RESULTS: The Atherosclerosis Risk in Communities Study recruited 14,477 adults from 45 to 64 years of age who were initially free of coronary heart disease. Coronary disease risk factors and several plasma hemostatic factors were measured, and incidence of coronary heart disease was ascertained during an average follow-up of 5.2 years. Age-, race-, and field center-adjusted relative risks of coronary heart disease were significantly elevated (P < or = .05) per higher value of fibrinogen (relative risk: men, 1.76; women, 1.54), white blood cell count (men, 1.68; women, 2.23), factor VIII coagulant activity (women, 1.25), and von Willebrand factor antigen (men, 1.20; women, 1.18). Adjustment for other risk factors attenuated these associations for fibrinogen (adjusted relative risk: men, 1.48; women, 1.21), and it eliminated the white blood cell count, factor VIII, and von Willebrand factor associations, consistent with the other risk factors either confounding or partly operating through their effects on the hemostatic variables. Adjusted standardized relative risks of total mortality, ranging from 1.13 to 1.37, were also elevated (P < .05) in relation to these four factors. There was no association of coronary disease incidence with factor VII, protein C, antithrombin III, or platelet count. CONCLUSIONS: Elevated levels of fibrinogen, white blood cell count, factor VIII, and von Willebrand factor are risk factors and may play causative roles in coronary heart disease. However, their measurement in healthy adults appears to add little to prediction of coronary events beyond that of more established risk factors.

Aged↗
PubMed1997

Associations of ankle-brachial index with clinical coronary heart disease, stroke and preclinical carotid and popliteal atherosclerosis: the Atherosclerosis Risk in Communities (ARIC) Study.

The resting ankle-brachial index (ABI) is a non-invasive method to assess the patency of the lower extremity arterial system and to screen for the presence of peripheral occlusive arterial disease. To determine how the ABI is associated with clinical coronary heart disease (CHD), stroke, preclinical carotid plaque and far wall intimal-medial thickness (IMT) of the carotid and popliteal arteries, we conducted analyses in 15 106 middle-aged adults from the baseline examination (1987-1989) of the Atherosclerosis Risk in Communities (ARIC) Study. The prevalence of clinical CHD, stroke/transient ischemic attack (TIA) and preclinical carotid plaque increased with decreasing ABI levels, particularly at those of < 0.90. Individuals with ABI < 0.90 were twice as likely to have prevalent CHD as those with ABI > 0.90 (age-adjusted odds ratio (OR) ranging from 2.2 (95% CI: 1.0-5.1) in African-American men to 3.3 (95% CI: 2.1-5.0) in white men). Men with ABI < 0.90 were more than four times as likely to have stroke/TIA as those with ABI > 0.90 (age-adjusted OR: 4.2 (95% CI: 1.8-9.5) in African-American men and 4.9 (95% CI: 2.6-9.0) in white men). In women the association was weaker and not statistically significant. Among those free of clinical cardiovascular disease, individuals with ABI < or = 0.90 had statistically significantly higher prevalence of preclinical carotid plaque compared to those with ABI > 0.90 (age-adjusted ORs ranging from 1.5 (95% CI: 1.0-1.9) in white women to 2.6 (95% CI: 1.0-6.6) in african-american men). The ABI was also inversely associated with far wall IMT of the carotid arteries (in both men and women) and the popliteal arteries (in men only). The associations of ABI with clinical CHD, stroke, preclinical carotid plaque and IMT of the carotid and popliteal arteries were attenuated and often not statistically significant after further adjustment for LDL cholesterol, cigarette smoking, hypertension and diabetes. These data demonstrate that low ABI levels, particularly those of < 0.90, are indicative of generalized atherosclerosis.

Ankle↗
PubMed1997

Vitamin intake: a possible determinant of plasma homocyst(e)ine among middle-aged adults.

PURPOSE: Many epidemiologic studies have identified elevated plasma homocyst(e)ine as a risk factor for atherosclerosis and thromboembolic disease. To examined the relationship between vitamin intakes and plasma homocyst(e)ine, we analyzed dietary intake data from a case-control study of 322 middle-aged individuals with atherosclerosis in the carotid artery and 318 control subjects without evidence of this disease. METHODS: All of these individuals were selected from a probability sample of 15,800 men and women who participated in the Atherosclerosis Risk in Communities (ARIC) Study. RESULTS: Plasma homocyst(e)ine was inversely associated with intakes of folate, vitamin B6, and vitamin B12 (controls only for this vitamin)--the three key vitamins in homocyst(e)ine metabolism. Among nonusers of vitamin supplement products, on average each tertile increase in intake of these vitamins was associated with 0.4 to 0.7 mumol/L decrease in plasma homocyst(e)ine. An inverse association of plasma homocyst(e)ine was also found with thiamin, riboflavin, calcium, phosphorus, and iron. Methionine and protein intake did not show any significant association with plasma homocyst(e)ine. CONCLUSIONS: In almost all analyses, cases and controls showed similar associations between dietary variables and plasma homocyst(e)ine. Plasma homocyst(e)ine among users of vitamin supplement products was 1.5 mumol/L lower than that among nonusers. Further studies to examine possible causal relationships among vitamin intake, plasma homocyst(e)ine, and cardiovascular disease are needed.

Analysis of Variance↗
PubMed1997

The relation of alcohol intake to coronary heart disease and all-cause mortality in a beer-drinking population.

Epidemiologic studies indicate that light to moderate alcohol consumption from beer, wine, or spirits is associated with a reduction in all-cause mortality, owing primarily to a reduced risk of coronary heart disease (CHD). To find out whether this protective effect of small to moderate amounts of alcohol could be confirmed in Germany, where much of the alcohol consumed is taken in the form of beer, we studied the relation between alcohol and CHD and total mortality in a population of southern Germany. We conducted a prospective cohort study from 1984 to 1992 among 1,071 men and 1,013 women, age 45-64 years at baseline, from the Augsburg region. Eighty-seven per cent of men and 56% of women reported drinking alcohol at baseline. Among drinkers, men had an average alcohol intake of 42 gm per day, of which 33 gm per day came from beer. Women who drank had an average alcohol intake of 16 gm per day and derived about half of it from beer and the other half from wine. During the 8 years of follow-up, 96 deaths (all causes) and 62 incident CHD events (nonfatal and fatal) occurred in men, and 45 deaths (all causes) occurred in women. Adjusting for a number of potential confounders, in men the adjusted hazard rate ratio (HRR) of CHD events for drinkers as compared with nondrinkers was 0.51 [95% confidence interval (CI) = 0.27-0.95]; this protective effect starts with the 0.1-19.9 gm per day alcohol category and does not change much with higher intake. In men, the adjusted total mortality HRR for drinkers as compared with nondrinkers was 0.59 (95% CI = 0.36-0.97). The total mortality HRRs for the different alcohol groups compared with nondrinkers show a U-shaped curve, with the lowest HRR of 0.46 (95% CI = 0.20-0.80) for the 20-39.9 gm per day alcohol group and an HRR of 1.04 (95% CI = 0.54-2.00) for the > or = 80 gm per day alcohol group. In women, the total mortality HRR for those drinking up to 19.9 gm per day as compared with nondrinkers was 0.46 (95% CI = 0.22-0.96).

Age Distribution↗
PubMed1997

Educational achievement recorded on certificates of death compared with self-report.

This study reports the agreement of educational achievement obtained from death certificates with self-report among 249 persons. Education was categorized as: less than high school, high school education, and greater than high school education. The overall agreement rate was 84%. Death certificates provided a slight underestimation of educational achievement. The sensitivity and specificity of the death certificate in classifying a decedent as having less than a high school education were both 90%. Educational achievement determined from death certificates has substantial validity, and any misclassification that may occur is likely to be similar across ethnicity and gender groups.

Age Factors↗
PubMed1997

Consistency of Doppler parameters in predicting arteriographically confirmed carotid stenosis. Asymptomatic Carotid Atherosclerosis Study Investigators.

BACKGROUND AND PURPOSE: While internal carotid peak systolic velocity (IPSV) is reportedly the best Doppler parameter for predicting lower grades of carotid artery stenosis, the internal carotid end-diastolic velocity (IEDV) or the ratio of IPSV to common carotid end-diastolic velocity (CEDV) is helpful in increasing prediction of higher grade stenoses. It is important to examine the consistency of these findings across machine and technician. METHODS: Using data from 10 devices from the Asymptomatic Carotid Atherosclerosis Study, we examined the predictive ability of seven Doppler parameters: IPSV, IEDV, CEDV, common carotid peak systolic velocity (CPSV), and the ratios of IPSV/ CEDV, IEDV/CEDV, and IEDV/CEDV. To assess the agreement between Doppler and arteriography in classifying percent stenosis above or below a given criterion, sensitivity, specificity, area under the receiver operating curve, and kappa statistics were obtained from logistic models. The single best Doppler parameter for each of two grades of stenosis (60% and 80%) was determined, and its predictive ability was compared with that of IPSV. The usefulness of IEDV or IPSV/CEDV in addition to IPSV to determine higher grade stenosis was examined. RESULTS: IPSV was the best predictor in 9 of 10 devices at 60% and in 4 devices at 80% stenosis. When another parameter was better than IPSV, the improvement was minimal. Including IEDV or IPSV/CEDV in addition to IPSV did not notably improve predictive ability. CONCLUSIONS: IPSV is the single best Doppler parameter for distinguishing severe (> 80%) from less severe carotid stenosis. Information from other Doppler parameters in addition to IPSV is unlikely to be helpful.

Blood Flow Velocity↗
PubMed1997

Validation of the ACAS TIA/stroke algorithm.

BACKGROUND AND PURPOSE: An easily administered questionnaire and algorithm classifying transient ischemic attacks (TIAs) or strokes, and also their distribution, could be invaluable for identifying endpoints in epidemiologic studies or clinical trials of prevention and therapy of cerebral ischemia. The Asymptomatic Carotid Atherosclerosis Study (ACAS) devised a symptom-based questionnaire and algorithm for detecting events in the trial. The purpose of this study was to determine sensitivity, specificity, and agreement rates of the questionnaire and algorithm against diagnoses of a panel of cerebrovascular disease authorities. METHODS: Three hundred eighty-one men and women at eight medical centers reported symptoms of stroke, TIA, or other neurologic illness. The questionnaire was administered by trained interviewers and the responses were analyzed using the algorithm. A standardized neurologic examination was performed by a neurologist. Data were submitted to two or more external reviewers. Sensitivity, specificity, and the kappa statistic (kappa) were used to evaluate the relationship between the algorithm and the external reviewers' diagnosis. RESULTS: Of the 381 reviews, 196 were diagnosed as TIA or stroke by the external panel. The algorithm's agreement with the diagnosis of TIA or stroke was 80.1%, and kappa was 0.60. Sensitivity was 87.8%, and specificity was 71.9%. CONCLUSION: While statistical agreement rates depend on the method of sample selection, the algorithm has a high agreement with an external panel of experts and is a sensitive tool for event detection. The lower specificity indicates that careful neurologic evaluation may be required to confirm or refute events identified by the screening algorithm.

Adult↗
PubMed1996

Self-reported transient ischemic attack and stroke symptoms: methods and baseline prevalence. The ARIC Study, 1987-1989.

As part of the Atherosclerosis Risk in Communities (ARIC) Study assessment of the etiology and sequelae of atherosclerosis, a standardized questionnaire on transient ischemic attack (TIA) and nonfatal stroke and a computerized diagnostic algorithm simulating clinical reasoning were developed and tested at the four ARIC field centers: Forsyth County, North Carolina; Minneapolis, Minnesota; Jackson, Mississippi; and Washington County, Maryland. The diagnostic algorithm used participant responses to a series of questions about six neurologic trigger symptoms to identify symptoms of TIA or stroke and their vascular distribution. Among 12,205 ARIO participants reporting their lifetime occurrence of one or more symptoms probably due to cerebrovascular causes, nearly half (47%) reported the sudden onset of at least one symptom sometime prior to their ARIC examination. Of those with at least one symptom, only 12.9% were classified by the computer algorithm as having symptoms of TIA or stroke. Dizziness/loss of balance was the most frequently reported symptom (36%); 1.2% of these persons were classified by the algorithm as having a TIA/stroke event. Positive symptoms of speech dysfunction were classified most often (77.%) as being symptoms of TIA or stroke. Symptoms suggesting TIA were reported more frequently than symptoms suggesting stroke by both sexes. TIA or stroke-like phenomena were more frequent (p < 0.001) in females (7%) than in males (5%) and increased with age in both sexes (p = 0.13 for females; p = 0.02 for males). In Forsyth County, TIA and stroke symptoms were greater in African Americans than in Caucasians (p = 0.05, controlling for sex). The association of algorithmically defined symptoms of TIA or stroke with traditional cerebrovascular risk factors is the subject of a companion paper.

Algorithms↗
PubMed1996

Association of transient ischemic attack/stroke symptoms assessed by standardized questionnaire and algorithm with cerebrovascular risk factors and carotid artery wall thickness. The ARIC Study, 1987-1989.

The baseline examination (1987-1989) for the Atherosclerosis Risk in Communities (ARIC) Study was conducted in 15,792 free-living residents aged 45-64 years in four geographically dispersed US communities. A questionnaire on symptoms of transient ischemic attack (TIA) and stroke was evaluated by computer algorithm for 12,205 of these participants. Data were also collected on lipoprotein levels, hemostasis, hematology, anthropometry, blood pressure, medical history, lifestyle, socioeconomic status, and medication use. Noninvasive high resolution B-mode ultrasonographic imaging was used to determine carotid arterial intimal-medial wall thickness (IMT). The cross-sectional relation between the prevalence of TIA/stroke symptoms and putative risk factors was assessed by logistic regression, controlling for age and community. Odds ratios for TIA/stroke symptoms were significantly elevated (p < or = 0.01) for diabetes mellitus, current smoking, hypertension, lower levels of education, income, and work activity, and higher levels of lipoprotein(a), IMT, hemostasis factor VIII, and von Willebrand factor. However, the relations with education and carotid IMT were not present for black Americans. In whites, the relations of TIA/stroke symptoms to IMT were nonlinear. Only at extreme levels of IMT were symptoms substantially more frequent: For example, men with an IMT greater than 1.17 mm or women with an IMT greater than 0.85 mm had approximately twice the odds of having positive TIA/stroke symptoms as those with lower IMTs. The authors plan in future analyses to address the issue prospectively, as well as to examine the relation with magnetic resonance imaging-defined outcomes and clinically defined incident stroke.

Algorithms↗
PubMed1996

Relation of hormone-replacement therapy to measures of plasma fibrinolytic activity. Atherosclerosis Risk in Communities (ARIC) Study Investigators.

BACKGROUND: The mechanisms by which replacement hormones may reduce the risk of coronary heart disease are not fully understood. Of specific interest is a potential effect of replacement hormones on plasma fibrinolytic activity, a putative determinant of thrombotic events. METHODS AND RESULTS: We investigated the relation of current use of replacement hormones to three measures of plasma fibrinolytic activity: tissue-type plasminogen activator (TPA) antigen, plasminogen activator inhibitor-1 (PAI-1) antigen, and D-dimer. The sample was composed of 288 women, free of clinical cardiovascular disease, who were selected for a case-control study of atherosclerosis: 142 women with ultrasonographic evidence of carotid intimal-medial thickening (cases) and 146 control subjects. Twenty percent (59 women) reported current use of replacement hormones. TPA antigen and PAI-1 antigen were highly correlated with each other (r = .67), whereas D-dimer correlated only weakly with TPA or PAI-1. Compared with nonusers, current users of replacement hormones had lower mean levels of TPA and PAI-1 antigens, suggesting enhanced fibrinolytic potential. In the entire sample, the multivariate-adjusted geometric mean values of TPA antigen were 6.3 and 7.3 ng/mL among current users and nonusers, respectively (P = .01); the corresponding values for PAI-1 antigen were 6.1 and 7.5 ng/mL (P = .13). These results were generally consistent for both atherosclerosis cases and their control subjects. D-dimer levels were lower in current hormone users than in nonusers, but the difference was not statistically significant (P > .15) in any of the analyses. CONCLUSIONS: The use of replacement hormones appears to be associated with enhancement of endogenous fibrinolytic potential. Enhanced plasma fibrinolytic activity among hormone users may explain, in part, the inverse association between hormone replacement therapy and coronary heart disease.

Alcohol Drinking↗