The Family Risk Score for coronary heart disease: associations with lipids, lipoproteins, and body habitus in a middle-aged bi-racial cohort: The ARIC study

Physical Activity, Parental History of Premature Coronary Heart Disease, and Incident Atherosclerotic Cardiovascular Disease in the Atherosclerosis Risk in Communities (ARIC) Study

Background

The effects of some atherosclerotic cardiovascular disease (ASCVD) risk factors vary according to whether an individual has a family history (FHx) of premature coronary heart disease (CHD). Physical activity (PA) is associated with reduced risk of ASCVD, but whether this association varies by FHx status is not well established.

Methods and Results

We evaluated 9996 participants free of ASCVD at baseline. FHx of premature CHD was defined as CHD occurring in a father before age 55 or mother before age 60. PA, assessed by a Baecke questionnaire, was converted into minutes/week of moderate or vigorous exercise and categorized per American Heart Association guidelines as recommended, intermediate, or poor. Incident ASCVD was defined as incident myocardial infarction, fatal CHD, or stroke. Multivariable‐adjusted Cox hazard models were used. The mean age was 54±6 years, 56% were women, and 21% of black race. Participants with and without a FHx of premature CHD reported similar levels of PA at baseline (423 versus 409 metabolic equivalents of task×min/week, respectively, P=0.852), and ≈40% of both groups met American Heart Association recommended PA levels. Over a mean follow−up of 20.9 years, there were 1723 incident ASCVD events. Compared to those with poor PA adherence to American Heart Association guidelines, participants who reported PA at recommended levels had significantly lower risk of incident ASCVD after adjustment for demographics and lifestyle factors (hazard ratio 0.84, 95% CI 0.74–0.94), but this association was not modified by FHx status (P−interaction=0.680).

Conclusions

PA was associated with a reduced risk of ASCVD among individuals with and without a FHx of premature CHD.

Ethnicity differences in plasma apoC-III levels between African American and Caucasian youths

BACKGROUND

Little is known about the association between apoC-III and lipoprotein-lipids in African American (AA) and Caucasian (CA) youths. The aim of this study was to investigate if plasma apoC-III level is associated with ethnicity differences in atherogenic lipoprotein-lipids between AA and CA youths.

METHODS

A total of 202 youths (mean age 16.1±1.3 y, range 13.8-18.9 y) consisting of 122 AA (boys/girls, 52/70) and 80 CA (boys/girls, 40/40) youths were recruited via flyers sent to local high schools. For AA youths, body mass index (BMI) values were 22.5±5.0 kg/m(2) and 25.0±6.8 kg/m(2) for boys and girls, respectively. For CA youths, BMI values were 22.0±4.8 kg/m(2) and 22.1±5.0 kg/m(2) for boys and girls, respectively. Anthropometric variables were measured using standard procedures. Body fat was measured by dual-energy X-ray absorptiometry. Fasting glucose and insulin, lipoprotein-lipids, and apolipoproteins were measured in fasting plasma samples.

RESULTS

AA youths had significantly lower values in apoC-III (P<0.001), triglyceride (P<0.001), and total cholesterol/high-density lipoprotein cholesterol (P=0.011) and higher values in HDLC (P=0.004), apoE (P=0.016), insulin (P=0.027), and homoeostasis model of assessment insulin resistance (HOMA-IR) (P=0.025) than CA youths. Body composition and insulin resistance parameters were significantly associated with apoC-III levels in CA youths, but not in AA youths. Regression analyses showed that waist circumference and HOMA-IR were significant predictors for apoC-III in CA, not AA, youths.

CONCLUSIONS

The findings of the current study suggest that ethnicity differences in atherogenic lipids between AA and CA youths may be associated with differences in apoC-III and apoE levels.

Family history in public health practice: a genomic tool for disease prevention and health promotion

Family history is a risk factor for many chronic diseases, including cancer, cardiovascular disease, and diabetes. Professional guidelines usually include family history to assess health risk, initiate interventions, and motivate behavioral changes. The advantages of family history over other genomic tools include a lower cost, greater acceptability, and a reflection of shared genetic and environmental factors. However, the utility of family history in public health has been poorly explored. To establish family history as a public health tool, it needs to be evaluated within the ACCE framework (analytical validity; clinical validity; clinical utility; and ethical, legal, and social issues). Currently, private and public organizations are developing tools to collect standardized family histories of many diseases. Their goal is to create family history tools that have decision support capabilities and are compatible with electronic health records. These advances will help realize the potential of family history as a public health tool.

A family longevity selection score: ranking sibships by their longevity, size, and availability for study

Family studies of exceptional longevity can potentially identify genetic and other factors contributing to long life and healthy aging. Although such studies seek families that are exceptionally long lived, they also need living members who can provide DNA and phenotype information. On the basis of these considerations, the authors developed a metric to rank families for selection into a family study of longevity. Their measure, the family longevity selection score (FLoSS), is the sum of 2 components: 1) an estimated family longevity score built from birth-, gender-, and nation-specific cohort survival probabilities and 2) a bonus for older living siblings. The authors examined properties of FLoSS-based family rankings by using data from 3 ongoing studies: the New England Centenarian Study, the Framingham Heart Study, and screenees for the Long Life Family Study. FLoSS-based selection yields families with exceptional longevity, satisfactory sibship sizes and numbers of living siblings, and high ages. Parameters in the FLoSS formula can be tailored for studies of specific populations or age ranges or with different conditions. The first component of the FLoSS also provides a conceptually sound survival measure to characterize exceptional longevity in individuals or families in various types of studies and correlates well with later-observed longevity.

Investigating the Genetic Determinants of Cardiovascular Disease Using Candidate Genes and Meta-analysis of Association Studies

Coronary artery disease (CAD) has a polygenic basis, and identification of CAD susceptibility genes has the potential to aid the development of new treatments and enhance prediction of disease risk. Thus far, the strategy has firstly been to choose "candidate" genes coding for important "rate-limiting" proteins in the homeostatic systems involved in maintaining cardiovascular health; secondly to identify common variants in these candidate genes; thirdly to carry out genotyping and statistical analysis using genetic association studies; and finally to test the functional effects of the identified variants in vitro and in vivo. However, lack of reproducibility of genetic association studies has led to uncertainty about the nature and number of genes involved. In part this is because many of the studies conducted have not been adequately powered to detect small risk effects, or to permit adequate exploration of gene-gene or gene-environment interactions in a robust manner. Spurious positive and negative associations due to type I and type II statistical errors are likely to co-exist with real associations in the published literature. By utilising all available data to increase statistical power, meta-analysis of genetic association studies is increasingly being used to identify genotypic risk with a greater degree of precision. Though potentially powerful, this approach may be prone to publication bias. Therefore, very large genetic association studies will also be required to identify risk genes for CAD. This review lays out the framework for the candidate gene approach for CAD and illustrates this with published results from a UK prospective study of 3000 middle-aged men.

Visceral Adiposity and Apolipoprotein C-III in Apolipoprotein B-Containing Lipoproteins Are Independent Predictors in Determining Atherogenic Lipid Profiles

BACKGROUND/AIMS

Little is known about how visceral adiposity and apolipoprotein CIII in apoB-containing lipoproteins influence atherogenic lipids profiles. The purpose of this study was to determine the relationships of visceral adiposity and apoC-III in apoB-containing lipoproteins (LpB:C-III) with lipoprotein lipids in circulating plasma.

METHODS

A subgroup of 46 men (n = 20, aged 29.1-33.4 years) and women (n = 26, aged 29.1-33.8 years) were recruited from an ongoing population study at our institution. Anthropometric variables including weight, height, and waist circumference were measured using standard procedures, and body mass index was calculated (kg/m(2)). Visceral adipose tissue (VAT) was measured with magnetic resonance imaging. Plasma apolipoproteins, lipids, glucose, and insulin were measured after an overnight fasting.

RESULTS

The men had a significantly higher waist circumference, glucose, and TC/HDL-C ratio, while the women had a significantly higher HDL-C and apoA-I. In particular, this is the first study to report that VAT and LpB:C-III were independent predictors in determining plasma triglyceride concentrations.

CONCLUSION

The relations of plasma triglyceride concentration with VAT and LpB:C-III suggest that information on VAT and apoC-III in apoB-containing lipoproteins may provide additional information on the atherogenic lipid profiles.

Modeling premature occurrence of acute coronary syndrome with atherogenic and thrombogenic risk factors and gene markers in extended families

BACKGROUND

The interaction between genetic and environmental risk factors in determining premature cardiovascular events has been largely investigated in case-control association studies. By contrast, few family based analyses have been performed so far.

PATIENTS/METHODS

From a series of 2936 subjects aged 45-64, we selected probands who died for a premature (<50 years) ischemic heart disease (IHD) and with at least one family member with a history of IHD also occurring under the age of 50. Ninety-four families from 32 pedigrees including 296 subjects were identified. In this population, we analyzed the relationship between background risk factors [age, gender, the G1691A polymorphisms of factor V gene, the C677T polymorphisms of the methylenetetrahydrofolate reductase (MTHFR) gene, the 844ins68bp polymorphisms of the cystathionine-beta-synthase (CBS) gene, and the apolipoprotein E (APOE) polymorphisms] and environmental risk factors, both atherogenic (smoke, hypertension, diabetes, dyslipidemia, obesity) and thrombogenic (smoke, homocysteine, fibrinogen) by a Markov block-recursive modeling approach.

RESULTS

None of the studied polymorphisms had an independent direct effect on the risk of IHD. As opposed to atherogenic factors, thrombogenic factors (homocysteine and fibrinogen) turned out to be possible mediators of the indirect effect of the MTHFR gene on IHD risk (OR: 1.30; 95% CI: 1.01-1.69, for every 8 mm increase in plasma levels of homocysteine in TT-carriers compared with CT/CC-carriers (OR: 1.11; 95% CI: 1.01-1.22), for every 20 g L(-1) increase in plasma levels of fibrinogen in TT-carriers compared with CT/CC-carriers).

CONCLUSION

Plasma levels of homocysteine and fibrinogen may be interpreted as intermediate factors mediating the effect of predisposing genes on the risk premature cardiovascular disease.

Measurement of abdominal fat by CT compared to waist circumference and BMI in explaining the presence of coronary calcium

OBJECTIVE

To evaluate the association between standard and computed tomography (CT)-based measures of obesity and subclinical atherosclerosis, defined as coronary artery calcium (CAC) by Electron Beam Computed Tomography (EBCT).

DESIGN

Cross-sectional, observational study of anthropometric and CT obesity measures and presence of CAC.

SUBJECTS

Participants were 383 men and 379 women, aged 20-58 y and asymptomatic for coronary artery disease (CAD).

MEASUREMENTS

Intra-abdominal fat (IAF) and subcutaneous fat (SQF) were measured at the level of lumbar 2-3 and 4-5 spaces, using EBCT. Body mass index (BMI) was calculated from height and weight, and minimum waist circumference and maximum hip circumference were measured. CAC was measured by EBCT.

RESULTS

In both men and women, BMI, waist circumference, IAF, and SQF were significantly related to CAC. However, BMI or waist circumference explained variation in the presence of CAC as well as IAF or SQF, univariately and after adjustment for additional cardiovascular risk factors.

CONCLUSION

CT-based obesity exposure measures are not superior to BMI or waist circumference in association studies of subclinical CAD.

Dyslipidemia and high waist-hip ratio in women with self-reported social anxiety

Previous research has indicated that phobic anxiety is associated with coronary heart disease. In this study, the possible association between social anxiety and various anthropometric, metabolic, and endocrine measurements known to be associated with cardiovascular disease were studied in a population-based cohort of 216 women 41-42 years old. Each participant was assessed by means of a DSM-IV based self-report questionnaire regarding social anxiety and related psychiatric diagnoses. Waist-to-hip ratio (WHR), body mass index (BMI), and serum levels of lipids and hormones were assessed. The prevalence of social anxiety was 14% (n=31). The social anxiety group displayed higher serum levels of triglycerides (1.3+/-0.9 vs. 1.0+/-0.5, P=0.003) and low-density lipoprotein (LDL) (3.3+/-0.8 vs. 3.0+/-0.7, P=0.03), but lower high-density lipoprotein (HDL) (1.4+/-0.3 vs. 1.6+/-0.4, P=0.04) and HDL/LDL ratio (0.46+/-0.15 vs. 0.57+/-0.22, P=0.008) than the other women. Serum levels of total testosterone (1.6+/-0.8 vs. 2.2+/-1.1, P=0.013) and free thyroxin (14+/-2 vs. 16+/-4, P=0.04) were lower in subjects confirming social anxiety. While WHR was significantly higher in the social anxiety group (0.83+/-0.06 vs. 0.80+/-0.07, P=0.016), BMI did not differ between the groups. Our data suggest that self-reported social anxiety is associated with two established risk factors for cardiovascular disease: dyslipidemia and increased WHR.

Apolipoprotein C-III SstI genotypes modulate exercise-induced hypotriglyceridemia

PURPOSE

To investigate whether the efficacy of exercise as an antitriglyceridemic treatment was dependent on the apolipoprotein (apo) C-III SstI gene polymorphism.

METHODS

A subgroup of 100 Korean men, who were prescreened by genotypes (S1S1 = 40, S1S2 = 40, S2S2 = 20), participated in a 6-d moderate-exercise intervention using either a motor-driven treadmill or a cycle ergometer. Height and weight for body mass index and waist circumference were measured. Fasting total cholesterol, triglycerides (TG), high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, glucose, and insulin were measured. Univariate analysis of variance and ANCOVA followed by Bonferroni post hoc tests were used to compare the preintervention values and the pre- to postexercise change (delta) scores in the measured variables across the genotypes, respectively. Multivariate linear regressions were carried out with age, smoking, waist circumference, body mass index, and genotype as independent variables and lipids, glucose, and insulin as dependent variables.

RESULTS

Subjects with the S2S2 genotype had a significantly higher preintervention TG concentration than subjects with the S1S1 genotype (P = 0.022). Waist circumference and genotype were the only significant predictors for the preintervention TG (P < 0.001). With respect to the delta scores, the subjects with the S2S2 genotype had a greater reduction in TG than the subjects with the S1S1 genotype, adjusted for the preintervention difference (P = 0.047).

CONCLUSION

This study suggests that the apo C-III SstI gene polymorphism might be useful for determining who is most susceptible to intervention by exercise in lowering fasting TG concentration.

Influence of selected lifestyle factors on risk of acute myocardial infarction in subjects with familial predisposition for the disease

BACKGROUND

The joint effect of family history of acute myocardial infarction (AMI) and selected adult life risk factors on the risk of the disease is not clear.

METHODS

We used the combined data set from three Italian case-control studies including 1737 cases of incident, nonfatal AMI and 2317 hospital controls, aged less than 75 years. An adult lifestyle risk score (ALRS) was computed, including tobacco, body mass index, physical activity, and consumption of coffee, alcohol, fish, and vegetables.

RESULTS

Compared to the reference category (subjects with no family history of AMI and low ALRS), the risk of AMI was 4.97 (95% confidence intervals, CI: 4.00-6.18) in subjects without family history and high ALRS, 2.19 (95% CI: 1.65-2.90) in subjects with family history and low ALRS, and 11.90 (95% CI: 8.94-15.84) in subjects with family history and high ALRS.

CONCLUSIONS

The risk of AMI in subjects with a familial predisposition to ischaemic heart disease might be substantially reduced by intervention on selected lifestyle risk factors for AMI. In absolute terms, any such intervention would be more effective than a comparable one on subjects without a familial predisposition.

Tracking of body mass index during childhood: a 15-year prospective population-based family study in eastern Finland

OBJECTIVES

To investigate the tracking of body mass index (BMI) during childhood. The effect of birth weight and family history of obesity on BMI development during childhood was also evaluated.

METHODS

All children born during 1981-1982 in a rural community of eastern Finland were followed at ages 6 months, 7 and 15 y (-6 m, -7y, -15y). Out of 205 children, 138 completed the full follow-up period, of which 100 (45 girls) were included in the analysis with complete data.

RESULTS

BMI-6 m was significantly associated with BMI-7y (r=0.320; P-value=0.001), but no longer with BMI-15y. BMI-7y was significantly associated with BMI-15y (r=0.686; P-value <0.001). Children in the highest tertile of BMI-6 m did not have a higher risk of being in the highest tertile of either BMI-7y or BMI-15y compared with children in other tertiles of BMI-6 m. Children in the highest tertile of BMI-7y had a significantly higher risk of being in the highest tertile of BMI-15y (relative risk=3.6 (2.0-6.3)) compared with children in other tertiles of BMI-7y. BMI-7y was predicted negatively by parents' education and male gender and positively by BMI-6 m. BMI-15y was predicted positively by BMI-7y, the difference in BMI between ages 7 y and 6 months and the mean of BMI between ages 6 months and 7 y. Birth weight was not a good predictor of BMI during childhood. Children with at least one obese parent seemed to have higher BMI during childhood; however, this association did not reach a significant level.

CONCLUSION

The study confirmed the tracking of BMI during childhood. Neither birth weight nor family history of obesity was found a good predictor of BMI during childhood. The risk of obesity in adolescence can be determined during middle childhood and obese children may be targeted in lifestyle advice to reverse this trend. Parental education may have a key role in the prevention of obesity during childhood.

[Effect of weight reduction on lipids and lipoprotein (a) serum levels]

BACKGROUND AND OBJECTIVE

A quasi-experimental study to determine the effects of a body weight reduction treatment on lipids and lipoprotein (a) serum levels.

PATIENTS AND METHOD

Ponderal and lipidogram values were determined in 69 premenopausic obese women before and after treatment. Differences were determined at a given time and at intervals.

RESULTS

Apart from a high fasting HDLc, a reduction of the lipid values was observed.

CONCLUSIONS

Our results suggest that weight reduction modifies favourably the lipid profile in premenopausic obese women.

Family studies: their role in the evaluation of genetic cardiovascular risk factors

Early epidemiological studies showed that genetic factors contribute to the risk of cardiovascular disease. Genetic epidemiological studies based upon families can be used to investigate familial trait aggregation, to localize genes implicated in cardiovascular diseases in the human genome, and to establish the role of environmental factors. Family studies can be also used to identify the physiological role of candidate genes for cardiovascular diseases, and to characterize shared environmental risk factors and their impact on the expression of genetic predisposition. The present paper reviews the existing family studies with special emphasis on those which have studied healthy populations in relation to cardiovascular disease such as the Framingham Heart Study, the National Heart, Lung, and Blood Institute Family Heart Study, and the STANISLAS cohort.

Epidemiology and prevention of coronary heart disease in families

Although family histories are used primarily to aid in diagnosis and risk assessment, their value is enhanced when the family is considered as a unit for research and disease prevention. The value of a family history of coronary heart disease (CHD) is increased when the age, sex, number of relatives, and age at onset of disease are incorporated in a quantitative family risk score. Medical and lifestyle risk factors that aggregate in families include dyslipidemia, hypertension, obesity, hyperfibrinogenemia, diabetes mellitus, smoking habits, eating patterns, alcohol consumption, physical activity, and socioeconomic status. Advances in detecting and understanding interactions between genetic susceptibility and modifiable risk factors should lead to improvements in prevention and treatment. However, working with families can be difficult. In the United States, families are usually small, are often widely dispersed, and may not be intact. Family histories may be unknown, affected relatives may be dead, and secular trends mask similarities among generations. Many exposures occur outside the home, and families change over time. Ethical, legal, and social issues arise when dealing with families. Nevertheless, opportunities are missed when research, clinical practice, and prevention focus on individual patients. Greater emphasis on families is needed to reduce the burden of CHD.