PubMed Health⌕ Search

Biomedical subjects

A R Sharrett

Publications and source records attributed to A R Sharrett.

At least 55 records · Page 3Linked to original sources
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

Clustering of dyslipidemia, hyperuricemia, diabetes, and hypertension and its association with fasting insulin and central and overall obesity in a general population. Atherosclerosis Risk in Communities Study Investigators.

Clustering of elevated triglycerides, decreased high-density lipoprotein cholesterol (HDL-C), hyperuricemia, diabetes, and hypertension has been related to insulin resistance/high insulin levels and central and/or overall obesity. The extent to which these abnormalities cluster and whether hyperinsulinemia, central adiposity, and overall obesity each independently associate with this clustering were evaluated in 14,481 US whites and African-Americans 45 to 64 years of age. With the exception of hypertension, abnormalities rarely existed in isolated form. Clustering greatly exceeded chance association (P < .001). Although this clustering was greater in relative terms (ratio of observed to expected cluster frequency) in the lean and less centrally obese, it was greater in absolute terms (observed minus expected cluster frequency as a percent of total population) in the more centrally and more generally obese. The greatest excesses were found for clusters that included both hypertriglyceridemia and low HDL-C. Multiple logistic regression models showed strong and independent graded relationships of clusters with quintiles of fasting insulin (fifth quintile odds ratio, 10 to 54, P < .001) and to a lesser degree with quintiles of the waist to hip ratio (2.2 to 5.4, P < .001 for most) and of body mass index (1.6 to 4.5, P < .05 for most). In conclusion, all abnormalities cluster in excess of that predicted by chance, with clusters showing remarkable and graded independent associations with fasting hyperinsulinemia and to a lesser extent with central and overall obesity. Thus, a metabolic syndrome occurs in both lean and obese middle-aged US adults.

Cluster Analysis↗
PubMed1996

Risk factors and segment-specific carotid arterial enlargement in the Atherosclerosis Risk in Communities (ARIC) cohort.

BACKGROUND AND PURPOSE: B-mode ultrasound imaging affords the opportunity to quantify both intimal-medial thickness (IMT) and lumen diameter of extracranial carotid arteries in ambulatory populations. Since the relation of IMT to lumen diameter may be complex, we asked whether cardiovascular disease risk factors (previously shown to be associated with greater arterial IMT) are related to smaller lumen diameters. METHODS: We used B-mode ultrasound to quantify lumen diameter, interadventitial diameter, and IMT of the extracranial carotid arteries and assessed the relationship of these measures to body mass index, smoking, low-density lipoprotein (LDL) and high-density lipoprotein cholesterol, hypertension, and diabetes in 6088 male and 7493 female participants in the Atherosclerosis Risk in Communities (ARIC) cohort. RESULTS: Smoking, hypertension, and LDL cholesterol were consistently related to greater IMT in the common and internal carotid arteries of men and women, as has been previously reported. In the internal carotid artery, smoking, hypertension, and LDL cholesterol were consistently related to smaller lumens. In the common carotid artery, body mass index, smoking, and hypertension were related to significantly larger, and LDL cholesterol to smaller, lumens. Thus, only LDL cholesterol was consistently associated with smaller lumens in both the common and internal carotid arteries. CONCLUSIONS: Risk factors relate positively to IMT in both the common and internal carotid arteries and inversely with lumen diameter in the internal carotid artery, in parallel with their relation to clinical events. However, their association with lumen diameters of the common carotid artery in population-based samples is more complex, and in some cases adverse levels of risk factors may be associated with larger lumens.

Arteriosclerosis↗
PubMed1996

A metabolic syndrome in whites and African-Americans. The Atherosclerosis Risk in Communities baseline study.

OBJECTIVE: To describe clustering of hypertriglyceridemia, low HDL cholesterol, hypertension, diabetes, and hyperuricemia and its association with fasting insulin, waist-to-hip ratio (WHR), and BMI for African-American and white men and women. RESEARCH DESIGN AND METHODS: Observed frequencies of clusters were compared with those expected in 14,481 participants, 45-64 years of age, of the Atherosclerosis Risk in Communities (ARIC) baseline survey, 1987-1989. Associations of clusters with insulin, central adiposity, and overall obesity, as well as with abnormalities, were analyzed through multiple logistic regression. RESULTS: Clustering beyond chance was observed in all four sex/ethnic groups (P < 0.001), with 7% of the sample presenting 30% of the abnormalities in large clusters (> or = 3 abnormalities per individual). The odds ratio (OR) for the association of each abnormality with clustering of the remaining four ranged from 1.6 to 8.8 (P < 0.01). These odds of clustering were notably large in white women. Of the abnormalities, hypertriglyceridemia demonstrated the highest OR (5.0-8.8) and diabetes had the lower OR in African-American subjects than in white subjects (P < 0.001). Insulin, WHR, and BMI were statistically associated with clustering in all groups (P < 0.001, except for BMI in African-Americans.

Arteriosclerosis↗
PubMed1995

Effect of apolipoprotein E polymorphism on fasting retinyl palmitate level.

The effect of apolipoprotein E (apo E) common genotypes on fasting retinyl palmitate (RP) level was studied in 344 white individuals, of which 130 had intimal thickening of the carotid artery ("cases") and 214 were controls. In this sample the common apo E genotypes possessed a statistically significant effect on fasting RP level in cases, while in controls the effect observed was not statistically significant. It is suggested that the effect of apo E may be expressed at the level of remnant clearance particles. Additionally, in cases other traits interact with the apo E genotype to influence fasting RP level.

Apolipoproteins E↗
PubMed1995

Associations of serum and dietary magnesium with cardiovascular disease, hypertension, diabetes, insulin, and carotid arterial wall thickness: the ARIC study. Atherosclerosis Risk in Communities Study.

The objective of this study was to examine the relationships of serum and dietary magnesium (Mg) with prevalent cardiovascular disease (CVD), hypertension, diabetes mellitus, fasting insulin, and average carotid intimal-medial wall thickness measured by B-mode ultrasound. A cross-sectional design was used. The setting was the Atherosclerosis Risk in Communities (ARIC) Study in four US communities. A total of 15,248 participants took part, male and female, black and white, aged 45-64 years. Fasting serum Mg, lipids, fasting glucose and insulin were measured; as was usual dietary intake by food frequency questionnaire and carotid intima-media thickness by standardized B-mode ultrasound methods. The results showed that serum Mg levels and dietary Mg intake were both lower in blacks than whites. Mean serum Mg levels were significantly lower in participants with prevalent CVD, hypertension, and diabetes than in those free of these diseases. In participants without CVD, serum Mg levels were also inversely associated with fasting serum insulin, glucose, systolic blood pressure and smoking. Dietary Mg intake was inversely associated with fasting serum insulin, plasma high density lipoprotein-cholesterol, systolic and diastolic blood pressure. Adjusted for age, race, body mass index, smoking, hypertension, Low density lipoprotein-cholesterol, and field center, mean carotid wall thickness increased in women by 0.0118 mm (p = 0.006) in diuretic users and 0.0048 mm (p = 0.017) in nonusers for each 0.1 mmol/l decrease in serum Mg level; the multivariate association in men was not significant. In conclusion, low serum and dietary Mg may be related to the etiologies of CVD, hypertension, diabetes, and atherosclerosis.

Black People↗
PubMed1995

Association of postprandial triglyceride and retinyl palmitate responses with asymptomatic carotid artery atherosclerosis in middle-aged men and women. The Atherosclerosis Risk in Communities (ARIC) Study.

Blood lipid alterations after a fatty meal may be atherogenic, but there is little information regarding their associations with disease independent of fasting lipids. Asymptomatic atherosclerosis cases (n = 229) and 373 control subjects free of atherosclerosis, as defined by carotid intima-media thickness on ultrasound images, were given a fatty meal with vitamin A, followed by 3.5- and 8-hour measurements of triglycerides (TGs), TG-rich lipoprotein TGs, apoproteinB48, and retinyl palmitate. Among white men and women but not among blacks, case status was associated with greater postprandial responses of TGs and TG-rich lipoprotein TGs, but only in nonobese persons (body mass index < 30 kg/m2). The associations were strong and significant after controlling for coronary risk factors (odds ratio, approximately 2.0) and fasting TGs (odds ratio, 1.5). Associations with other postprandial lipid measurements did not persist after controlling for fasting lipids. Elevated postprandial TGs appear to be an independent risk factor for carotid intimal thickening in nonobese whites. The lack of such a relation in obese subjects and the lipid profile they manifest suggest that postprandial TGs must be accompanied by accumulation of TG-rich lipoprotein remnants to be atherogenic.

Apolipoprotein B-48↗
PubMed1995

Arterial wall thickness is associated with prevalent cardiovascular disease in middle-aged adults. The Atherosclerosis Risk in Communities (ARIC) Study.

BACKGROUND AND PURPOSE: This study was done to assess the relationship between prevalent cardiovascular disease and arterial wall thickness in middle-aged US adults. METHODS: The association of preexisting coronary heart disease, cerebrovascular disease, and peripheral vascular disease with carotid and popliteal intimal-medial thickness (IMT) (measured by B-mode ultrasound) was assessed in 13,870 black and white men and women, aged 45 to 64, during the Atherosclerosis Risk in Communities (ARIC) Study baseline examination (1987 through 1989). Prevalent disease was determined according to both participant self-report and measurements at the baseline examination (including electrocardiogram, fasting blood glucose, and medication use). RESULTS: Across four race and gender strata, mean carotid far wall IMT was consistently greater in participants with prevalent clinical cardiovascular disease than in disease-free subjects. Similarly, the prevalence of cardiovascular disease was consistently greater in participants with progressively thicker IMT. The greatest differences in carotid IMT associated with prevalent disease were observed for reported symptomatic peripheral vascular disease (0.09 to 0.22 mm greater IMT in the four race-gender groups). CONCLUSIONS: These data document the substantially greater arterial wall thickness observed in middle-aged adults with prevalent cardiovascular disease. Both carotid and popliteal arterial IMT were related to clinically manifest cardiovascular disease affecting distant vascular beds, such as the cerebral, peripheral, and coronary artery vascular beds.

Age Factors↗
PubMed1994

Associations of allelic differences at the A-I/C-III/A-IV gene cluster with carotid artery intima-media thickness and plasma lipid transport in hypercholesterolemic-hypertriglyceridemic humans.

Individuals with elevated levels of plasma cholesterol and triglyceride may be at higher risk for coronary artery disease than those with isolated elevations of either cholesterol or triglyceride. Sequence variation in the A-I/C-III/A-IV gene cluster has been implicated in the etiology of some disorders associated with premature atherosclerosis and/or hypertriglyceridemias with or without elevations of cholesterol. This led to the hypothesis that allelic variation at this gene locus alters plasma lipid transport and affects susceptibility for atherosclerosis. The study population, from the Atherosclerosis Risk in Communities (ARIC) Study, consisted of 50 normolipidemic individuals, 48 subjects with elevated plasma cholesterol, 47 subjects with elevated plasma triglyceride, and 123 subjects with both elevated plasma cholesterol and triglyceride who were used to evaluate associations between an Xmn I polymorphic site 2.5 kilobase pairs (kbp) upstream of the structural gene for apolipoprotein (apo) A-I, intimal-medial thickening of the extracranial carotid arteries, and several plasma lipid factors. The relative allele frequencies of the 8.3-kbp allele and the 6.6-kbp allele were .86 and .14, respectively, in the entire study population and did not differ among the lipid phenotypes. In the group with elevated plasma cholesterol and triglyceride, subjects possessing the 6.6-kbp allele exhibited a greater carotid artery intimal-medial thickness (P = .034) and higher plasma levels of apoA-I, high-density lipoprotein (HDL) cholesterol, and HDL3 cholesterol (P < .02) than subjects homozygous for the 8.3-kbp allele. In contrast, subjects with the 6.6-kbp allele displayed lower mean ratios of apolipoproteins C-II to C-III, C-II to A-IV and E to A-IV in plasma (P < .05) and a lower mean ratio of apolipoprotein C-II to C-III in the triglyceride-rich lipoproteins (P = .026). Sequence variation in or near the genes encoding apolipoproteins A-I, C-III, and A-IV may therefore identify a group of hypercholesterolemic-hypertriglyceridemic persons who are at higher risk for atherosclerosis than others with the same lipoprotein phenotype.

Adult↗
PubMed1994

Associations of lipoprotein cholesterols, apolipoproteins A-I and B, and triglycerides with carotid atherosclerosis and coronary heart disease. The Atherosclerosis Risk in Communities (ARIC) Study.

Previous research shows generally greater proportional elevation in apolipoprotein B (apoB) levels than in low-density lipoprotein cholesterol (LDL-C) in coronary heart disease (CHD) case subjects compared with control subjects. The Atherosclerosis Risk in Communities study provided general populations of 7261 men and women free of cardiovascular symptoms for evaluating the associations between intima-media thickening in extracranial carotid arteries measured using ultrasound imaging and fasting plasma LDL-C, high-density lipoprotein cholesterol (HDL-C), apoB, apolipoprotein A-I (apoA-I), triglycerides, and HDL density subfractions. A CHD group was selected for comparison. Lipid factors show approximately linear associations with carotid thickness: positive for LDL-C and plasma apoB and negative for HDL-C and apoA-I levels. Apolipoproteins and HDL density subfractions did not contribute to the association after accounting for LDL-C and HDL-C. Compared with control subjects, persons whose carotid thickness exceeded 0.9 mm had greater proportional elevations in LDL-C than in apoB, whereas HDL-C reductions were small. CHD case subjects showed greater proportional elevations of apoB than LDL-C. Although the lipid profiles associated with asymptomatic carotid wall thickening and stenotic coronary disease are similar, the differences found suggest that LDL-C is the most important lipid factor in earlier stages of atherogenesis, whereas the metabolism of triglyceride-rich lipoproteins and its effects on LDL and HDL may be more relevant to later atherothrombotic processes.

Apolipoprotein A-I↗
PubMed1994

B-mode-detected carotid artery plaque in a general population. Atherosclerosis Risk in Communities (ARIC) Study Investigators.

BACKGROUND AND PURPOSE: There is little information on the distribution of atherosclerotic lesions of the extracranial carotid artery wall in free-living populations. The purpose of the present study was to describe the prevalence from 1987 through 1989 of extracranial carotid artery plaque and plaque with acoustic attenuation (shadowing) lesions in a general population of white and black adults from four US communities. METHODS: B-mode ultrasound was used to characterize wall lesions in the common and internal carotid arteries and at the carotid artery bifurcation in 14,046 men and women 45 to 64 years old who participated in the Atherosclerosis Risk in Communities Study baseline survey. RESULTS: Thirty-four percent of participants had plaque and 6.4% had plaque with acoustic shadowing. The prevalence of plaque with acoustic shadowing increased steadily with age from 2.5% at ages 45 to 49 to 12.4% at ages 60 to 64. Overall, whites had more plaque with acoustic shadowing lesions than blacks (odds ratio [OR], 1.22; 95% confidence interval [CI], 1.02 to 1.46), and men had more than women (OR, 1.42; 95% CI, 1.22 to 1.63). However, plaque lesions in the common carotid artery were less common among whites than among blacks, and no racial difference was observed in the prevalence of plaque with acoustic shadowing at this segment. CONCLUSIONS: Although these prevalence rates are likely to be underestimated because of the emphasis on arterial boundary visualization of the scanning protocol, they show a large, mostly asymptomatic burden of atherosclerosis in these populations, especially among older individuals. Site-specific frequency rates of plaque varied between blacks and whites. Among those with plaque, however, whites had more lesions with acoustic shadowing attenuation.

Adult↗
PubMed1994

Arterial enlargement in the atherosclerosis risk in communities (ARIC) cohort. In vivo quantification of carotid arterial enlargement. The ARIC Investigators.

BACKGROUND AND PURPOSE: The relation between arterial wall (intimal-medial) thickness and lumen narrowing is complex and has previously been studied predominantly at autopsy. B-mode ultrasound affords the opportunity to visualize both wall and lumen of the extracranial carotid arteries in vivo. Several studies have quantified the relation of various independent variables to wall thickness of carotid arteries in population-based samples, but the relation of age and wall thickness to interadventitial and lumen diameter has not previously been investigated in these samples. METHODS: We used B-mode ultrasound to quantify the relation of arterial lumen diameter to age, arterial wall thickness, and arterial size (interadventitial diameter) of the extracranial carotid artery in 13,711 members of the Atherosclerosis Risk in Communities (ARIC) cohort. RESULTS: Men had greater interadventitial diameters, thicker walls, and wider lumens than women. Wall thicknesses of the common carotid artery were greater by 21% in men and 22% in women aged 60 to 64 years compared with those aged 45 to 49 years (P < .001). However, lumen diameters were also greater in older individuals because interadventitial diameters were greater. Wall thickness of the internal carotid artery was also associated positively with age, but the lumen diameter of the internal carotid artery was smaller in older individuals. Diameters of the carotid artery segments also differed in their relation to arterial wall thickening. The lumen of the internal carotid artery was uniformly progressively narrower with increasing wall thickness. For the common carotid artery greater wall thickness bore only a small correlation with narrower lumen diameter for thickening of the arterial wall up to 1.2 mm, but the association was more marked for the range of thicknesses between 1.2 mm and 2.5 mm. CONCLUSIONS: When arterial enlargement accompanies increased wall thickness, less lumen constriction results than expected. Quantification of these complex relations in vivo may provide new insight into the pathogenesis of symptoms related to vascular disease. Narrowing of the internal carotid artery lumen associated with thicker walls is consistent with the observation that stenosis develops in this region and often leads to symptoms.

Age Factors↗
PubMed1994

Apolipoprotein E polymorphism influences postprandial retinyl palmitate but not triglyceride concentrations.

To quantify the effect of the apolipoprotein (apo) E polymorphism on the magnitude of postprandial lipemia, we have defined its role in determining the response to a single high-fat meal in a large sample of (N = 474) individuals taking part in the biethnic Atherosclerosis Risk in Communities Study. The profile of postprandial response in plasma was monitored over 8 h by triglyceride, triglyceride-rich lipoprotein (TGRL)-triglyceride, apo B-48/apo B-100 ratio, and retinyl palmitate concentrations, and the apo E polymorphism was determined by DNA amplification and digestion. The frequency of the apo E alleles and their effects on fasting lipid levels in this sample were similar to those reported elsewhere. Postprandial plasma retinyl palmitate response to a high-fat meal with vitamin A was significantly different among apo E genotypes, with delayed clearance in individuals with an epsilon 2 allele, compared with epsilon 3/3 and epsilon 3/4 individuals. In the sample of 397 Caucasians, average retinyl palmitate response was 1,489 micrograms/dl in epsilon 2/3 individuals, compared with 1,037 micrograms/dl in epsilon 3/3 individuals and 1,108 micrograms/dl in epsilon 3/4 individuals. The apo E polymorphism accounted for 7.1% of the interindividual variation in postprandial retinyl palmitate response, a contribution proportionally greater than its well-known effect on fasting LDL-cholesterol. However, despite this effect on postprandial retinyl palmitate, the profile of postprandial triglyceride response was not significantly different among apo E genotypes. The profile of postprandial response was consistent between the sample of Caucasians and a smaller sample of black subjects. While these data indicate that the removal of remnant particles from circulation is delayed in subjects with the epsilon 2/3 genotype, there is no reported evidence that the epsilon 2 allele predisposes to coronary artery disease (CAD). The results of this study provide not only a reliable estimate of the magnitude of the effect of the apo E polymorphism on various measurements commonly used to characterize postprandial lipemia, but also provide mechanistic insight into the effects of the apo E gene polymorphism on postprandial lipemia and CAD.

Apolipoproteins B↗
PubMed1993

Lipoprotein[a] as a risk factor for preclinical atherosclerosis.

Elevated mean levels of lipoprotein[a] (Lp[a]) have been associated with symptomatic cardiovascular diseases such as clinically manifest myocardial infarction (MI), coronary artery disease, restenosis of coronary artery vein grafts after bypass, and a family history of MI. Associations of Lp[a] with arterial wall thickening in asymptomatic individuals previously have not been addressed and are evaluated in this report among participants of the Atherosclerosis Risk in Communities (ARIC) Study. Intima-media wall thickening in the extracranial carotid arteries was assessed noninvasively with B-mode ultrasonography; Lp[a] was measured as its total protein component. Individuals with wall thickening > or = 90th percentile of the population maximum far-wall thickness were pair matched to participants < 75th percentile of wall thickness by race, gender, center, 10-year age group, and time of examination. These selection criteria yielded 492 matched pairs, with 395 white pairs and 97 black pairs. The mean Lp[a] protein level for all black participants was 174.6 micrograms/mL compared with 77.8 micrograms/mL for whites. Conditional logistic regression analysis for the association of Lp[a] with case-control status yielded a statistically significant prevalence odds ratio (OR) estimate of 1.49, based on a 1-SD difference in Lp[a] protein, after adjusting for age, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, fibrinogen, hypertension, and cigarette smoking. None of these risk factors significantly altered the OR, in agreement with reports that Lp[a] is unaffected by environmental influences. In addition, no differential effect of Lp[a] protein on case-control status (effect modification) was observed by race, gender, low-density lipoprotein cholesterol, or fibrinogen in this population.(ABSTRACT TRUNCATED AT 250 WORDS)

Arteriosclerosis↗
PubMed1993

Carotid artery intimal-medial thickness distribution in general populations as evaluated by B-mode ultrasound. ARIC Investigators.

BACKGROUND AND PURPOSE: B-mode ultrasound is a widely used technique for the clinical and epidemiological assessment of carotid atherosclerosis. This article provides a description of the distribution of carotid atherosclerosis in the general population. METHODS: Intimal-medial arterial wall thickness was measured by B-mode real-time ultrasound as an index of atherosclerotic involvement in the extracranial carotid arteries as part of the population-based Atherosclerosis Risk in Communities (ARIC) study. The distribution was described by race-sex strata, in which 759 to 4952 individuals were imaged depending on strata and location in the carotid system. RESULTS: Median wall thickness ranged between 0.5 and 1 mm at all ages; fewer than 5% of ARIC participants had values exceeding 2 mm. Individuals tended to have a larger wall thickness in the carotid bifurcation than in the common carotid artery. Internal carotid artery values were more variable, with higher proportions of both large and small wall thicknesses than in the common carotid. The proportion of individuals with a large wall thickness was greatest at the bifurcation and smallest at the common carotid artery. Men had uniformly larger wall thickness than women. Cross-sectional analysis suggests that age-related increases in wall thickness average approximately 0.015 mm/y in women and 0.018 mm/y in men in the carotid bifurcation, 0.010 mm/y for women and 0.014 mm/y for men in the internal carotid artery, and 0.010 mm/y in both sexes in the common carotid artery. CONCLUSIONS: Estimates provided for wall thickness percentiles can serve as "nomograms" by age, race, and sex.

Arteriosclerosis↗
PubMed1993

Invasive versus noninvasive studies of risk factors and atherosclerosis.

Associations of risk factors with atherosclerosis may be assessed by either invasive methods for measuring the arterial disease, such as angiography, or noninvasive methods; these methods differ in their potential for bias. Biases associated with coronary angiography may be difficult to control in statistical analysis, either because they are unrecognized or because they are amenable to neither stratification nor multivariate analysis. Problems in control selection include the likelihood that angiography controls overrepresent related ischemic or noncoronary cardiac conditions with their own risk factor associations. Differential misclassification is more likely in the clinical setting when invasive studies are used than in a research setting involving ultrasound imaging of carotid arteries. Nondifferential misclassification, however, affects both types of studies and clouds interpretation of the comparative strength of risk factor associations with atherosclerosis assessed by the two methods. Recent angiographic studies have generally provided insufficient information to evaluate these biases. However, with proper attention to such biases, one may be able to learn much about early and late stages of atherosclerosis by comparing risk factor associations with disease measured by both coronary angiography and carotid ultrasound.

Angiography↗
PubMed1992

Postprandial lipemia: reliability in an epidemiologic field study.

Ten subjects from the Forsyth County, North Carolina, and Washington County, Maryland, field centers in the Atherosclerosis Risk in Communities Study had two fat tolerance tests within a 10-day period from September 1988 to February 1989 to determine the reproducibility of markers for postprandial lipemia. No significant differences between visits were found in fasting mean plasma lipids, lipoproteins, and apolipoproteins. Postprandial triglycerides and retinyl palmitate were measured at 3.5 and 9.0 hours after the test meal in whole plasma. There were no significant differences in the mean levels of these analytes between visits. The correlation of triglycerides between repeat visits at 9.0 hours (r = 0.87) was stronger than in fasting samples (r = 0.67) or at 3.5 hours (r = 0.69). The mean plasma retinyl palmitate level at 3.5 hours was 15% higher than at the 9.0-hour level. The correlation of repeat measures of retinyl palmitate at 9.0 hours (r = 0.94) was much stronger than at 3.5 hours (r = 0.79). In conclusion, estimates of reliability in postprandial measurements of 9.0-hour triglycerides and retinyl palmitate levels were as strong as fasting lipid measurements of total cholesterol, high density lipoprotein cholesterol, low density lipoprotein cholesterol, and high density lipoprotein cholesterol, and both postprandial triglyceride measurements exceeded that of fasting triglyceride (r = 0.67).

Apolipoproteins↗