Family risk score of coronary heart disease (CHD) as a predictor of CHD: the Atherosclerosis Risk in Communities (ARIC) study and the NHLBI family heart study

Developing and Validating Risk Scores for Predicting Major Cardiovascular Events Using Population Surveys Linked with Electronic Health Insurance Records

A risk prediction model for major cardiovascular events was developed using population survey data linked to National Health Insurance (NHI) claim data and the death registry. Another set of population survey data were used to validate the model. The model was built using the Nutrition and Health Survey in Taiwan (NAHSIT) collected from 1993–1996 and linked with 10 years of events from NHI data. Major adverse cardiovascular events (MACEs) were identified based on hospital admission or death from coronary heart disease or stroke. The Taiwanese Survey on Hypertension, Hyperglycemia, and Hyperlipidemia (TwSHHH), conducted in 2002 was used for external validation. The NAHSIT data consisted of 1658 men and 1652 women aged 35–70 years. The incidence rates for MACE per 1000 person-years were 13.77 for men and 7.76 for women. These incidence rates for the TwSHHH were 7.27 for men and 3.58 for women. The model had reasonable discrimination (C-indexes: 0.76 for men; 0.75 for women), thus can be used to predict MACE risks in the general population. NHI data can be used to identify disease statuses if the definition and algorithm are clearly defined. Precise preventive health services in Taiwan can be based on this model.

Basic vs More Complex Definitions of Family History in the Prediction of Coronary Heart Disease: The Multi-Ethnic Study of Atherosclerosis

OBJECTIVE

To determine whether family history of coronary heart disease (FH) definitions differ in their association with atherosclerotic cardiovascular disease (ASCVD) events.

PATIENTS AND METHODS

Participants who provided FH data from July 17, 2000, through February 24, 2004, were identified. Definitions of FH were any, premature, and Familial Risk Assessment (FRA). Outcomes included coronary heart disease (CHD), stroke, peripheral artery disease, angina, and congestive heart failure. Multivariable-adjusted Cox models examined the association of FH definitions with events. C statistics and the net reclassification index examined the incremental prognostic contribution of each definition.

RESULTS

In 6200 participants, the proportions of any FH and premature FH were 36% and 16%, respectively, and of weak, moderate, and strong familial risk were 20%, 16%, and 20%, respectively. Over median follow-up of 10.1 years (range, 0.02-11.5 years), 741 participants experienced a composite event. Compared with no FH, any FH was associated with incident CHD, angina, and composite ASCVD (hazard ratios [95% CIs]: 1.4 [1.1-1.8], 1.6 [1.2-2.1], and 1.3 [1.1-1.5], respectively). Similar results were obtained for premature FH compared with no FH and for strong compared with weak FRA for these 3 outcomes. There was no association between the FH definitions and noncoronary cardiovascular events. Compared with traditional risk factors (C statistic = 0.740), any FH, premature FH, and FRA all improved discrimination of composite ASCVD (all P < .01); however, the differences in C statistics among any FH (0.743), premature FH (0.742), and FRA (0.744) were numerically small, as were differences in the net reclassification index.

CONCLUSION

A single question regarding the presence of FH in any first-degree relative performs just as well as more complicated assessments in predicting CHD.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT00005487.

Methods for Polygenic Traits

An important aspect of public health is disease prediction and health promotion through better targeting of preventive strategies. Well-targeted preventive strategies will eventually decrease burden of diseases and thus precise prediction plays a crucial role in public health. Many investigators put efforts into finding models that improve prediction using known risk factors of diseases. Recently with the overwhelming load of genetic loci discovered for complex diseases through genome-wide association studies (GWAS), much of attention has been focused on the role of these genetic loci to improve prediction models. Genetic loci in solo explain little variance of diseases. It is thus necessary to create new genetic parameters that combine the effect of as many genetic loci as possible. Such new parameters aim to better distinguish individuals who will develop a disease from those who will not. In this chapter, various polygenic methods that use multiple genetic loci to directly or indirectly improve precision of genetic prediction are discussed.

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.

Clinically relevant lessons from Family HealthLink: a cancer and coronary heart disease familial risk assessment tool

PURPOSE

A descriptive retrospective study was performed using two separate user cohorts to determine the effectiveness of Family HealthLink as a clinical triage tool.

METHODS

Cohort 1 consisted of 2,502 users who accessed the public website. Cohort 2 consisted of 194 new patients in a Comprehensive Breast Center setting. For patient users, we assessed documentation of family history and genetics referral. For all users seen in a genetics clinic, the Family HealthLink assessment was compared with that performed by genetic counselors and genetic testing outcomes.

RESULTS

For general public users, the percentage meeting high-risk criteria were: for cancer only, 22.2%; for coronary heart disease only, 24.3%; and for both diseases, 10.4%. These risk stratification percentages were similar for the patient users. For the patient users, there often was documentation of family history of certain cancer types by oncology professionals, but age of onset and coronary heart disease family history were less complete. Of 142 with high-risk assignments seen in a genetics clinic, 130 (91.5%) of these assignments were corroborated. Forty-two underwent genetic testing and 17 (40.5%) had new molecular diagnoses established.

CONCLUSION

A significant percentage of individuals are at high familial risk and may require more intensive screening and referral. Interactive family history triage tools can aid this process.Genet Med 17 6, 493-500.

Clinical profile and impact of family history of premature coronary artery disease on clinical outcomes of patients undergoing primary percutaneous coronary intervention for ST-elevation myocardial infarction: analysis from the HORIZONS-AMI Trial

BACKGROUND/PURPOSE

Family history of coronary artery disease (CAD) is a well-established risk factor of future cardiovascular events. The authors sought to examine the relationship between family history of CAD and clinical profile and prognosis of patients with ST-elevation myocardial infarction (STEMI) undergoing primary percutaneous coronary intervention (PCI).

MATERIALS/METHODS

Baseline features and clinical outcomes at 30 days and at 3 years from 3601 patients with STEMI enrolled in the HORIZONS-AMI trial were compared in patients with and without family history of premature CAD, which was present in 1059 patients (29.4%).

RESULTS

These patients were younger (median 56.7 vs. 62.1years, P<0.0001) and more often current smokers (52.4% vs. 43.5%, P<0.0001), had more dyslipidemia (47.7% vs. 41.1%, P=0.0003), less diabetes mellitus (14.1% vs. 17.5%, P=0.01) and had shorter symptom onset to balloon times (median 213 vs. 225 min, P=0.02). Patients with a family history of premature CAD had higher rates of final TIMI 3 flow (93.8% vs. 90.6%, P=0.002), and myocardial blush grade 2 or 3 (83.2% vs. 78.0% P=0.0008), and fewer procedural complications. Although the unadjusted 30-day and 3-year mortality rates were lower in patients with a family history of premature CAD (1.8% vs. 3.0%, P=0.046 and 4.8% vs. 7.7%, P=0.002, respectively), by multivariable analysis the presence of a family history of premature CAD was not an independent predictor of death at 3 years (HR [95%CI]=1.00 [0.70, 1.44], P=0.98).

CONCLUSIONS

A family history of premature CAD is not an independent predictor of higher mortality.

Improving assessment of cardiovascular disease risk by using family history: an integrative literature review

BACKGROUND

Cardiovascular disease (CVD) is the number one killer in the United States. Although the causes of CVD are multifactorial, including genetic and environmental influences, it is largely a preventable disease. The cornerstone of CVD prevention is accuracy in risk prediction to identify patients who will benefit from interventions aimed at reducing risk. Nurse practitioners commonly perform CVD risk assessments and are well positioned to impact preventive therapy. Cardiovascular disease risk scoring systems currently in use substantially underestimate risk in large part because these do not include family history of premature CVD as a high-risk factor.

PURPOSE

We sought to examine the state of evidence for the use of family history as a predictor in CVD risk stratification.

CONCLUSIONS

A comprehensive literature search using the Medical Subject Headings terms of family history of CVD, family history of premature CVD, risk assessment, and risk estimation displayed 416 articles; a review of the titles and subsequent evaluation of the articles eliminated 392 references, leaving 24 for review. By incorporating family history in risk assessment, categorization of CVD risk improves substantially. The evidence demonstrates that family history is an independent contributor to risk appraisal and unequivocally supports its incorporation to improve accuracy in global CVD risk estimation.

CLINICAL IMPLICATIONS

Underestimation of CVD risk leaves patients and providers misinformed, promoting the ongoing epidemic of chronic disease. Translating this evidence into practice by establishing a clinical algorithm that incorporates family history into risk prediction will standardize CVD risk assessment, improve the identification of high-risk patients, and provide the indicated aggressive care to prevent CVD.

Associations between a parental history of premature cardiovascular disease and coronary artery calcium and carotid intima-media thickness: the Coronary Artery Risk Development In Young Adults (CARDIA) study

BACKGROUND

It is unclear if associations between a parental history of premature CVD (pCVD) and subclinical atherosclerosis are attenuated by adjustment for long-term risk factor levels through middle adulthood.

DESIGN

Prospective community-based cohort study.

METHODS

CARDIA participants who attended the year-20 exam (n = 2283, mean age 45 years) were grouped by pCVD status: maternal only, paternal only, any parental, and no parental history (referent). We used separate logistic regression models, adjusted for average risk factor levels over a 20-year follow up to assess associations of parental pCVD and subclinical atherosclerosis in offspring.

RESULTS

White participants with any parental history of pCVD had a higher odds of coronary artery calcium (CAC) >0 than participants with no parental history (OR 1.55, 95% CI 1.01-2.37). This was largely driven by the association of a paternal history of pCVD with CAC >0 (OR 2.15, 95% CI 1.42-3.23), which was minimally attenuated by multivariable adjustment (OR 2.09, 95% CI 1.31-3.32). Similarly, adjusted associations between parental pCVD and intima-media thickness (IMT) >90% were observed in white participants with a paternal history of pCVD (OR 1.93, 95% CI 1.10-3.39) and any parental history pCVD (OR 1.67, 95% CI 1.02-2.74). No significant associations between a parental history of pCVD and the odds of subclinical atherosclerosis were observed in black participants.

CONCLUSIONS

Parental pCVD is independently associated with early development of subclinical atherosclerosis; these associations may be race-specific for participants in their fifth decade of life.

Prevalence Pattern of Risk Factors for Coronary Artery Disease among Patients Presenting for Coronary Artery Bypass Grafting in Oman

OBJECTIVES

To identify the pattern of prevalence of risk factors in patients presenting for coronary artery bypass grafting at a single center in Oman.

METHODS

All patients who had coronary artery bypass grafting between March 2008 to March 2010 were included and data were obtained from history and laboratory investigations. The prevalence rates of eight conventional risk factors are presented as a retrospective single center observational study.

RESULTS

Out of 146 total patients, 107 (73.29%) were male. The age ranged from 31 to 87 years old. The mean age was 58.18 ± 10.08 years (males = 56.81 ± 10.42, females = 61.95 ± 7.97). Hypertension was present in 119 patients (81.51%), 115 patients (78.77%) had dyslipidemia, 107 patients (73.29%) were male, 79 patients (54.11%) had diabetes mellitus, 70 patients (47.95%) were over the age of 60 years, 41 patients (28.08%) gave a history of smoking, 31 patients (21.23%) were obese, and 19 patients (13.01%) gave a positive family history.

CONCLUSIONS

The most common risk factor was hypertension, followed by dyslipidemia, male gender, diabetes mellitus, old age, smoking, obesity and positive family history; 87.7% had three or more risk factors. The females in this study were older than the males and had more risk factors at presentation. The most common combination of factors seen together was diabetes, hypertension, dyslipidemia and male gender.

Should your family history of coronary heart disease scare you?

Traditional risk factors explain most of the risk associated with coronary heart disease, and after adjustment for risk factors family history was believed to contribute very little to population-attributable risk of coronary heart disease. However, the INTERHEART study demonstrated an independent association of family history of coronary heart disease with acute myocardial infarction. To assess this relationship more comprehensively in multiple datasets in different populations, we carried out a detailed review of the available evidence. Case-control studies involving 17,202 cases and 30,088 controls yielded a pooled unadjusted odds ratio (random-effects model, overall I(2) = 64.6%, P = 0.000) of 2.03 (95% confidence interval: 1.79-2.30), whereas cohort studies that included 313,837 individuals yielded an unadjusted relative risk for future coronary heart disease (random-effects model, overall I(2) = 88.7%, P = 0.000) of 1.60 (95% confidence interval: 1.44-1.77). Although the presence of family history of coronary heart disease indicates a cumulative exposure of shared genes and environment, the risk estimates for family history did not attenuate significantly after adjustment for conventional coronary heart disease risk factors in several studies. It is probably an oversimplification to dichotomize the family history variable into a simple "yes" or "no" risk factor, as the significance of family history is influenced by several variables, such as age, sex, number of relatives, and age at onset of disease in the relatives. Moreover, a quantitative risk-assessment model for the family history variable, such as the "family risk score," has a positive linear relationship with coronary heart disease. More studies are warranted to assess the benefits and risks of intensive interventions, both targeted individually and at the family level, among individuals with a valid family history and borderline elevated risk factors.

Impact of family history of coronary artery disease in young individuals (from the CONFIRM registry)

Although family history (FH) of coronary artery disease (CAD) is considered a risk factor for future cardiovascular events, the prevalence, extent, severity, and prognosis of young patients with FH of CAD have been inadequately studied. From 27,125 consecutive patients who underwent coronary computed tomographic angiography, 6,308 young patients (men aged <55 years and women aged <65 years) without known CAD were identified. Obstructive CAD was defined as >50% stenosis in a coronary artery >2 mm diameter. Risk-adjusted logistic regression, Kaplan-Meier, and Cox proportional-hazards models were used to compare patients with and without FH of CAD. Compared with subjects without FH of CAD, those with FH of CAD (FH+) had higher prevalences of any CAD (40% vs 30%, p <0.001) and obstructive CAD (11% vs 7%, p <0.001), with multivariate odds of FH+ increasing the likelihood of obstructive CAD by 71% (p <0.001). After a mean follow-up period of 2 ± 1 years (42 myocardial infarctions and 39 all-cause deaths), FH+ patients experienced higher annual rates of myocardial infarction (0.5% vs 0.2%, log-rank p = 0.001), with a positive FH the strongest predictor of myocardial infarction (hazard ratio 2.6, 95% confidence interval 1.4 to 4.8, p = 0.002). In conclusion, young FH+ patients have higher presence, extent, and severity of CAD, which are associated with increased risk for myocardial infarction. Compared with other clinical CAD risk factors, positive FH in young patients is the strongest clinical predictor of future unheralded myocardial infarction.

Perceived familiarity with and importance of family health history among a medically underserved population

Inadequate knowledge of family health history (FHH) continues to be a major obstacle limiting its usefulness in public health and clinical practice; strategies to facilitate FHH dissemination are needed. Data (N = 1,334) were obtained through waiting-room surveys completed by a diverse sample of patients attending three community health centers. Perceptions about the importance of genetic information (β = 0.13, p < 0.001; β = 0.11, p < 0.001) and higher genetic self-efficacy (β = 0.14, p < 0.001; β = 0.23, p < 0.001) were significantly associated with higher levels of perceived familiarity with and importance of FHH, respectively. Furthermore, beliefs about genetic causation of illnesses (β = 0.12, p < 0.001) and a wider reach of health communication within one's family (β = 0.15, p < 0.001) were associated with higher levels of perceived familiarity with one's FHH. Participants in the oldest group (>50 years) reported higher familiarity than those in the youngest (18-25 years). Those with higher familiarity were significantly less likely to answer "don't know" when reporting diabetes and heart disease diagnoses among immediate (OR = 0.35 and OR = 0.29, respectively) and extended (OR = 0.50 and OR = 0.46, respectively) family members. Having a wider health communication reach within a family may be beneficial in increasing familiarity with FHH; however, the reported levels of communication reach were limited among most participants. Women, older-generation family members, and those who believe in the importance of genetics in health or feel confident about using genetic information may be particularly important as targets of public health interventions to facilitate FHH dissemination within families.

Parental history and lifestyle behaviors in relation to mortality from stroke among Japanese men and women: the Japan Collaborative Cohort Study

BACKGROUND

We assessed the impact of parental history of stroke on stroke mortality, as well as the effect modification between lifestyle and stroke mortality, among Japanese.

METHODS

In this community-based, prospective cohort study, 22,763 men and 30,928 women aged 40 to 79 years with no history of cardiovascular disease or cancer at baseline (1988-1990) were followed through 2008. We examined the association between parental history of stroke and stroke mortality and estimated the impact of the combination of lifestyle and parental history on stroke mortality in offspring.

RESULTS

During a mean follow-up period of 15.9 years, there were 1502 stroke deaths. In both sexes, participants with a parental history of stroke had a higher risk of stroke mortality as compared with those without such a history. The respective multivariable hazard ratio (95% CI) and population attributable fraction were 1.28 (1.10-1.49) and 5.4% in men, 1.22 (1.04-1.43) and 4.3% in women, and 1.25 (1.12-1.40) and 4.8% in all participants, for offspring with a maternal and/or paternal history of stroke. There was an inverse association between healthy-lifestyle score and stroke mortality, irrespective of parental history of stroke. The overall multivariable hazard ratio for the highest (6-8) versus the lowest (0-3) score categories was 0.56 (95% CI, 0.43-0.72) for participants with a maternal and/or paternal history of stroke and 0.44 (0.36-0.53) for those without such a history.

CONCLUSIONS

Parental history of stroke was associated with stroke mortality in offspring. The inverse association between healthy lifestyle behaviors and stroke mortality, regardless of parental history, suggests that lifestyle modification is beneficial, even among individuals with a parental history of stroke.

Association between family history and coronary heart disease death across long-term follow-up in men: the Cooper Center Longitudinal Study

BACKGROUND

Family history of coronary heart disease (CHD) has been well studied as an independent risk factor for CHD events in the short term (<10 years). However, data are sparse on the association between family history and risk for CHD across long-term follow-up.

METHODS AND RESULTS

We included 49 255 men from the Cooper Center Longitudinal Study. Premature family history of CHD was defined as the presence of angina, myocardial infarction, angioplasty, or bypass surgery in a relative <50 years of age. Cause-specific mortality was obtained from the National Death Index. The association between premature family history and cardiovascular disease (CVD) or CHD death was compared across 3 unique follow-up periods (0-10, >10-20, and >20 years). Lifetime risk was estimated by use of a modified survival analytic technique adjusted for competing risk with non-CVD death as the competing event. After 811 708 person-years of follow-up, there were 919 CHD deaths and 1456 CVD deaths. After adjustment for traditional risk factors, premature family history was associated with CHD mortality >10 to 20 years (1.59; 95% confidence interval, 1.14-2.22) and >20 years (1.43; 95% confidence interval, 1.05-1.95) with wider confidence intervals at 0 to 10 years (1.32; 95% confidence interval, 0.76-2.31). Similar findings were observed for CVD mortality. Compared with men without a family history of coronary artery disease, premature family history was associated with an ≈50% higher lifetime risk for both CHD and CVD mortality (13.7% versus 8.9% and 21% versus 14.1%, respectively).

CONCLUSION

Premature family history was associated with a persistent increase in both CHD and CVD mortality risk across long-term follow-up, resulting in significantly higher lifetime risk estimates.

Familial [corrected] transmission of coronary heart disease: a cohort study of 80,214 Swedish adoptees linked to their biological and adoptive parents

BACKGROUND

Studies of adoptees have the potential to disentangle the contributions of genetic versus family environmental factors in the familial [corrected] transmission of coronary heart disease (CHD) because adoptees do not share the same family environment as their biological parents. The aims of this study were as follows: (1) to examine the risk of CHD in adopted men and women with at least one biological parent with CHD and (2) to examine the risk of CHD in adopted men and women with at least one adoptive parent with CHD.

METHODS

The Swedish Multigenerational register was used to follow all Swedish-born adoptees (born in or after 1932, n = 80,214) between January 1, 1973, and December 31, 2008, for CHD. The risk of CHD was estimated in adopted men and women with at least one biological parent with CHD and adopted men and women with at least one adoptive parent with CHD. The control groups consisted of adopted men or women without a biological parent with CHD or adopted men or women without an adoptive parent with CHD.

RESULTS

Adopted men and women with at least one biological parent with CHD (n = 749) were 1.4 to 1.6 times (statistically significant, 95% CI) more likely to have CHD than adoptees without a biological parent with CHD. In contrast, men and women with at least one adoptive parent with CHD (n = 1,009) were not at increased risk of the disease.

CONCLUSIONS

These findings (based on validated hospital diagnoses unbiased by recall) suggest that the familial [corrected] transmission of CHD from parents to offspring is more related to genetic factors than to family environmental factors.

Genomewide linkage and peakwide association analyses of carotid plaque in Caribbean Hispanics

BACKGROUND AND PURPOSE

Atherosclerosis is a complex subclinical cardiovascular disorder with a substantial genetic component. This study sought to identify genetic loci influencing carotid plaque in 2 independent samples.

METHODS

B-mode ultrasound was performed to determine the presence and area of carotid plaque. Variance components analysis was used to test for linkage using 383 autosomal microsatellite markers in 1308 subjects from 100 Dominican families. Multiple linear and logistic regression models were used to investigate the association between plaque traits and 18,904 single nucleotide polymorphisms under the 1-logarithm of odds unit down regions of linkage peaks in an independent community-based data set (N = 941, 41% Dominicans) from the Northern Manhattan Study.

RESULTS

After adjustment for age, hypertension, diabetes mellitus, cigarette pack-years, body mass index, and waist-to-hip ratio, significant heritability was detected for plaque presence (h² = 0.50 ± 0.14, P < 0.0001) and plaque area (h²=0.17 ± 0.04, P < 0.0001). Quantitative and dichotomous trait linkage analyses obtained similar results and identified 4 regions with multipoint logarithm of odds scores ≥ 2.00 on 7q36, 11p15, 14q32, and 15q23. In the association analysis of the 4 linkage peaks, several single nucleotide polymorphisms in or near SOX6, FSD2, AP3S2, EFTUD1, and MYOD1 were associated with carotid plaque traits with a nominal P ≤ 0.0005 in the Northern Manhattan Study data set and with a P ≤ 0.01 in Northern Manhattan Study Dominican subset.

CONCLUSIONS

Carotid plaque has considerable heritability and may be influenced by loci on chromosomes 11p15, 14q32, and 15q23. The SOX6 gene within the bone morphogenic protein pathway could be a candidate for carotid plaque. Larger independent studies are needed to validate these findings.

Family history of premature coronary heart disease and risk prediction in the EPIC-Norfolk prospective population study

OBJECTIVE

The value of a family history for coronary heart disease (CHD) in addition to established cardiovascular risk factors in predicting an individual's risk of CHD is unclear. In the European Prospective Investigation of Cancer (EPIC)-Norfolk cohort, the authors tested whether adding family history of premature CHD in first-degree relatives improves risk prediction compared with the Framingham risk score (FRS) alone.

METHODS AND RESULTS

This study comprised 10,288 men and 12,553 women aged 40-79 years participating in the EPIC-Norfolk cohort who were followed for a mean of 10.9±2.1 years (mean±SD). The authors computed the FRS as well as a modified score taking into account family history of premature CHD. A family history of CHD was indeed associated with an increased risk of future CHD, independent of established risk factors (FRS-adjusted HR of 1.74 (95% CI 1.56 to 1.95) for family history of premature CHD). However, adding family history of CHD to the FRS resulted in a negative net reclassification of 2%. In the subgroup of individuals estimated to be at intermediate risk, family history of premature CHD resulted in an increase in net reclassification of 2%. The sensitivity increased with 0.4%, and the specificity decreased 0.8%.

CONCLUSION

Although family history of CHD was an independent risk factor of future CHD, its use did not improve classification of individuals into clinically relevant risk categories based on the FRS. Among study participants at intermediate risk of CHD, adding family history of premature CHD resulted in, at best, a modest improvement in reclassification of individuals into a more accurate risk category.

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.

Family history of myocardial infarction predicts incident coronary heart disease in postmenopausal women with diabetes: the Women's Health Initiative Observational Study

BACKGROUND

Diabetes is a risk factor for coronary heart disease (CHD) but CHD does not occur in all diabetic individuals. The goal of this study was to assess the relationship between family history of myocardial infarction (MI) and incident CHD in diabetic postmenopausal women.

METHODS

We conducted a prospective cohort study among 2642 diabetic postmenopausal women without CHD at baseline in the Women's Health Initiative Observational Study. Family history was defined as a proband report of MI in first-degree relatives. Incident CHD was defined as non-fatal MI, coronary revascularization, or CHD death.

RESULTS

During 7.3 ( +/- 1.8) years of follow-up, 14.3% of the participants had incident CHD. The risk of incident CHD was 50% higher (HR = 1.50, 95% CI: 1.20-1.87, p = 0.0003) in those with a family history of an MI in at least one first-degree relative, and 79% higher (HR = 1.79, 95% CI: 1.36-2.35, P < 0.0001) if two or more first-degree relatives had an MI, compared to participants without a family history, after adjustment for covariates. The CHD risk increased with elevated systolic blood pressure (SBP) (HR = 1.01, 95% CI: 1.003-1.02, p = 0.001) but decreased with elevated diastolic BP (HR = 0.98, 95% CI: 0.97-0.999, p = 0.005) and with two or more episodes per week of physical activity (HR = 0.70, 95% CI: 0.52-0.93, p = 0.02).

CONCLUSIONS

The results suggest that a family history of MI predicts CHD in diabetic postmenopausal women. Close attention should be paid to BP control and physical activity in these women.

A new estimate of family disease history providing improved prediction of disease risks

Complex diseases often aggregate within families and using the history of family members' disease can potentially increase the accuracy of the risk assessment and allow clinicians to better target on high risk individuals. However, available family risk scores do not reflect the age of disease onset, gender and family structures simultaneously. In this paper, we propose an alternative approach for a family risk score, the stratified log-rank family score (SLFS), which incorporates the age of disease onset of family members, gender differences and the relationship among family members. Via simulation, we demonstrate that the new SLFS is more closely associated with the true family risk for the disease and more robust to family sizes than two existing methods. We apply our proposed method and the two existing methods to a study of stroke and heart disease. The results show that assessing family history can improve the prediction of disease risks and the SLFS has strongest positive associations with both myocardial infarction and stroke.

Prospective analysis of traffic exposure as a risk factor for incident coronary heart disease: the Atherosclerosis Risk in Communities (ARIC) study

BACKGROUND

For people living close to busy roads, traffic is a major source of air pollution. Few prospective data have been published on the effects of long-term exposure to traffic on the incidence of coronary heart disease (CHD).

OBJECTIVES

In this article, we examined the association between long-term traffic exposure and incidence of fatal and nonfatal CHD in a population-based prospective cohort study.

METHODS

We studied 13,309 middle-age men and women in the Atherosclerosis Risk in Communities study, without previous CHD at enrollment, from 1987 to 1989 in four U.S. communities. Geographic information system-mapped traffic density and distance to major roads served as measures of traffic exposure. We examined the association between traffic exposure and incident CHD using proportional hazards regression models, with adjustment for background air pollution and a wide range of individual cardiovascular risk factors.

RESULTS

Over an average of 13 years of follow-up, 976 subjects developed CHD. Relative to those in the lowest quartile of traffic density, the adjusted hazard ratio (HR) in the highest quartile was 1.32 [95% confidence interval (CI), 1.06-1.65; p-value for trend across quartiles = 0.042]. When we treated traffic density as a continuous variable, the adjusted HR per one unit increase of log-transformed density was 1.03 (95% CI, 1.01-1.05; p = 0.006). For residents living within 300 m of major roads compared with those living farther away, the adjusted HR was 1.12 (95% CI, 0.95-1.32; p = 0.189). We found little evidence of effect modification for sex, smoking status, obesity, low-density lipoprotein cholesterol level, hypertension, age, or education.

CONCLUSION

Higher long-term exposure to traffic is associated with incidence of CHD, independent of other risk factors. These prospective data support an effect of traffic-related air pollution on the development of CHD in middle-age persons.

Mechanisms of disease: The genetic basis of coronary heart disease

Since completion of the human genome sequence, considerable progress has been made in determining the genetic basis of human diseases. Understanding the genetic basis of coronary heart disease (CHD), the leading cause of mortality in developed countries, is a priority. Here we provide an update on the genetic basis of CHD, focusing mainly on the clinical manifestations rather than the risk factors, most of which are heritable and also influenced by genetic factors. The challenges faced when identifying clinically relevant genetic determinants of CHD include phenotypic and genetic heterogeneity, and gene-gene and gene-environment interactions. In addition, the etiologic spectrum includes common genetic variants with small effects, as well as rare genetic variants with large effects. Advances such as the cataloging of human genetic variation, new statistical approaches for analyzing massive amounts of genetic data, and the development of high-throughput single-nucleotide polymorphism genotyping platforms, will increase the likelihood of success in the search for genetic determinants of CHD. Such knowledge could refine cardiovascular risk stratification and facilitate the development of new therapies.

Family history of premature coronary heart disease and coronary artery calcification: Multi-Ethnic Study of Atherosclerosis (MESA)

BACKGROUND

A family history of premature coronary heart disease (CHD) is a known risk factor for CHD events. The purpose of this study was to assess the strength of the association between a family history of premature CHD and coronary artery calcification (CAC) in a multiethnic cohort of asymptomatic individuals. We also sought to determine whether individuals with a reported family history of premature CHD have an increased atherosclerotic burden among those classified as being at low to intermediate risk on the basis of the conventional Framingham risk score.

METHODS AND RESULTS

The association of family history of premature CHD with CAC was assessed in 5347 asymptomatic individuals (47% men; mean age 62+/-10 years) in the Multi-Ethnic Study of Atherosclerosis (MESA). The demographics (age, gender, and race)-adjusted OR for CAC > 0 with versus without a family history of premature CHD was 1.94 (95% CI, 1.64 to 2.29). On adjustment for CHD risk factors, the association was slightly attenuated to an OR of 1.84 (95% CI, 1.55 to 2.19). Family history of premature CHD was significantly associated with CAC in all ethnic groups. The age-, gender-, and race-adjusted prevalence of CAC > 0 was significantly higher with presence of any family history of premature CHD than for those with no family history of premature CHD among individuals classified as low risk (35% versus 23%, P<0.0001) and among those at intermediate risk (70% versus 60%, P=0.01). Similarly, the prevalence of age-gender-race-based CAC > or = 75th percentile in low-risk (24% versus 14%, P=0.0003) and intermediate-risk (34% versus 20%, P<0.001) individuals was also higher among those with a family history of premature CHD. Compared with those without a family history of premature CHD, the association with the presence of CAC was strongest in participants reporting such history in both a parent and a sibling (odds ratio, 2.74; 95% CI, 1.64 to 4.59), followed by those reporting a family history in a sibling only (odds ratio, 2.06; 95% CI, 1.64 to 2.58) and those reporting a family history of premature CHD only in a parent (odds ratio, 1.52; 95% CI, 1.19 to 1.93).

CONCLUSIONS

An association between family history of premature CHD and the presence of any CAC, as well as advanced CAC, was observed in the present population-based multiethnic study. The relationship was independent of other risk factors and Framingham risk score, which supports the utility of including information on family history of premature CHD in current methods of global risk assessment and practice guidelines.

Importance of Family History in Lifestyle Management

Families affect the health of their members by transmitting genetic predisposition to wellness and illness. Families also model and teach health beliefs, attitudes, and behaviors. Eliciting an individual's family history can identify potential genetic vulnerabilities to disease and lifestyle influences. This review explores the implications of family history for patient education about lifestyle. Family history is particularly useful for helping health care providers be effective with individuals who have strong family patterns of atherosclerotic cardiovascular disease, major risk factors (dyslipidemia, hypertension, diabetes, and tobacco use), and related factors (obesity, poor nutrition, physical inactivity, and alcohol excess). Gathering and recording family history information can be problematic, even with an electronic medical record (EMR). The genogram (expanded genetic pedigree) is an efficient way to record and display family history data. Family history data in genogram format can be used as a versatile patient education tool. Despite its clinical utility, the genogram has been used more for teaching than for patient care. Thus far, the genogram has not been integrated into the EMR. Adding relevant cultural information to the conventional genogram might increase its utility for helping health care providers encourage lifestyle changes that promote wellness and prevent disease, disability, and premature death in ethnically diverse populations.

Differences in maternal and paternal transmission of coronary heart disease

BACKGROUND

Few studies have investigated the possible differential transmission of maternal and/or paternal coronary heart disease (CHD) to offspring, after accounting for sociodemographic characteristics.

METHODS

The Multigeneration Register was linked to hospital data in this study of all Swedish individuals born since 1932 and their parents. Registered cases of CHD between January 1, 1987, and December 31, 2001, were evaluated. Poisson regression was used to calculate standardized incidence ratios (SIRs) for men and women with mothers and/or fathers affected by CHD compared with men and women whose parents were not affected. All analyses were conducted in 2005.

RESULTS

Maternal transmission was stronger than paternal transmission and the confidence intervals did not overlap. For women, the overall SIRs were 1.43 (95% confidence interval [CI]=1.34-1.51) for maternal transmission and 1.17 (95% CI=1.11-1.23) for paternal transmission. For men, the corresponding SIRs were 1.55 (95% CI=1.50-1.60) and 1.41 (95% CI=1.37-1.45). Even higher SIRs were found in the youngest age groups, among those with both parents affected by coronary heart disease, and among those with premature parental CHD.

CONCLUSIONS

These findings might ultimately influence treatment decisions regarding risk factors and suggest the need for research focusing on genetic and intrauterine risk factors.

Gene by sex interaction in the etiology of coronary heart disease and the preceding metabolic syndrome

BACKGROUND

Despite decades of research, the genetic basis of coronary heart disease and its metabolic risk factors is poorly understood. Few studies consider that sex may modify the effect of gene variants on disease. Investigation of gene by sex interaction may help to elucidate underlying genetic susceptibilities and explain the sexual dimorphism of these complex traits.

AIMS

The aim of this review is to summarize evidence for gene by sex interaction in the etiology of coronary heart disease and the metabolic syndrome.

DATA SYNTHESIS

Published literature was examined in the areas of familial aggregation of coronary heart disease; heritability of body mass, insulin resistance, hypertension and dyslipidemia; genome-wide linkage analysis in humans and rodents; and large-scale genetic association studies. Possible mechanisms of gene by sex interaction are discussed including X-linked inheritance, confounding by risk factors and the effect of sex hormones.

CONCLUSIONS

The strongest evidence for gene by sex interaction in relation to coronary heart disease and the metabolic syndrome is in the etiology of body mass, insulin resistance and possibly dyslipidemia. Genetic studies of these traits would benefit from taking sex differences into account. Alternative mechanisms underlying gene by sex interaction, besides obvious sex hormone differences, should be considered.

Family history of coronary heart disease: evidence-based applications

Clinicians sometimes consider family history of CHD when evaluating CHD risk and deciding whether to prescribe a lipid medication. Most clinicians who take family history of CHD into account do so by categorically adjusting the aggressiveness of patient education and preventive medication recommendations (eg, from a low-key informational mode to a more direct influential or persuasive mode). Quantitative methods exist for taking into account any family history of CHD in parents and siblings, when estimating an individual's 10-year risk for a CHD event; at present, these methods are not readily available. For those individuals who have a positive family history of CHD, using family history-adjusted risk estimates could help clinicians more accurately target high-risk individuals who are the most appropriate candidates for therapeutic lifestyle changes and dyslipidemia drug therapy. Electronic health records (EHR) that now include CHD risk estimation as a decision support feature exclude family history from the calculation. Unless family CHD history is included in EHR decision support modules, family history of CHD will be increasingly discounted or ignored, as clinicians come to rely more and more on computerized decision support aids.

Impact of a Community-Based Multiple Risk Factor Intervention on Cardiovascular Risk in Black Families With a History of Premature Coronary Disease

BACKGROUND

Black subjects with a family history of premature coronary heart disease (CHD) have a marked excess risk, yet barriers prevent effective risk reduction. We tested a community-based multiple risk factor intervention (community-based care [CBC]) and compared it with "enhanced" primary care (EPC) to reduce CHD risk in high-risk black families.

METHODS AND RESULTS

Black 30- to 59-year-old siblings of a proband with CHD aged <60 years were randomized for care of BP > or =140/90 mm Hg, LDL cholesterol > or =3.37 mmol/L, or current smoking to EPC (n=168) or CBC (n=196) and monitored for 1 year. EPC and CBC were designed to eliminate barriers to care. The CBC group received care by a nurse practitioner and a community health worker in a community setting. The CBC group was 2 times more likely to achieve goal levels of LDL cholesterol and blood pressure compared with the EPC group (95% CI, 1.11 to 4.20 and 1.39 to 3.88, respectively) with adjustment for baseline levels of age, sex, education, and baseline use of medications. The CBC group demonstrated a significant reduction in global CHD risk, whereas no reduction was seen in the EPC group (P<0.0001).

CONCLUSIONS

Eliminating known barriers may not be sufficient to reduce CHD risk in primary care settings. An alternative community care model that addresses barriers may be a more effective way to ameliorate CHD risk in high-risk black families.

Genetic influences on CHD-death and the impact of known risk factors: comparison of two frailty models

The importance of some recognized risk factors on genetic influences for coronary heart disease (CHD) needs further clarification. The aim of the present study was therefore to study the impact of known risk factors on genetic influences for CHD-death. Both twin (correlated gamma-frailty) and non-twin models (univariate gamma-frailty) were utilized and compared regarding their suitability for genetic analyses. The study population consisted of twins born in Sweden between 1886 and 1925. As expected, our findings indicate that genetic influences are important for CHD-death. Inclusion of risk factors in the twin-model increased heritability estimates, primarily due to a substantial reduction in non-shared environmental variances. The genetic influences for CHD-death are only marginally mediated through the risk factors among males, but more so among females. Although the outcome phenotype used in the present study is not behavioral, the analyses demonstrate the potential of frailty models for quantitative genetic analyses of categorical phenotypes.

The effect of disease penetrance, family size, and age of onset on family history with application to setting eligibility criteria for genetic testing

The concept of family history of disease has been used as a surrogate for genetic susceptibility in many epidemiological studies and has also been important as a criterion for selecting individuals for genetic testing. However, little is known about the precise interplay between the true genetic model (genotype-specific penetrances, age of onset distribution), life expectancy, and reproductive patterns in determining the level of family history. In order to address these questions, we performed a simulation study to address these relationships. Factors examined were the age-, sex-, and genotype-specific penetrance of the disease and the distribution of the number of offspring per family. When considering the average number of affected individuals among first-degree relatives of mutation positive probands, penetrance-related factors accounted for 64% of the variance in the average number of affected first-degree relatives, and 58% of the variance in the number of affected first- or second-degree relatives. In general, the average proportion of mutation-positive probands with at least one affected first-degree relative was low, especially for a sex-limited disease, ranging between 20% and 46%, depending on the lifetime penetrance in mutation carriers. Lack of family history among first-degree relatives of mutation positive probands is not necessarily unexpected even for loci conferring relatively high lifetime risk. In selecting probands for genetic testing, we found that under a wide variety of conditions, criteria based on the number of affected among first- and second-degree relatives were superior to those based on first-degree family history alone.

Family history is a coronary heart disease risk factor in the Second Northwick Park Heart Study

We have estimated the risk of coronary heart disease (CHD) from family history of CHD (FHCHD) in 2827 healthy European middle-aged men, and explored the extent to which this can be explained by classical and genetic risk factors. Men with FHCHD (obtained by questionnaire) had a hazard ratio of CHD of 1.73 (95% confidence interval: 1.30, 2.31) compared to those without FHCHD; after adjusting for classical risk factors this did not change substantially. Those with FHCHD had 2.3% lower Factor VIIc (p = 0.03) and 1.14% higher systolic and 1.21% higher diastolic blood pressure (p = 0.04 and p = 0.02), with evidence of interaction between blood pressure and FHCHD status on risk (p = 0.01). The risk for those with a positive family history who were also current smokers was 3.01 compared to non-smokers without FHCHD, which is greater than the risk posed by smoking or FHCHD alone (1.96 and 2.05 respectively compared to non-smokers without FHCHD), but not significantly different from a multiplicative model (p-value for interaction 0.33). Allele frequencies for 13 candidate gene variants were not significantly different between those with and without FHCHD. In those with FHCHD, current smokers who carried the APOE4 allele (e4+) had a hazard ratio of 5.66 compared to non-smokers who had no FHCHD and were not APOE4+, with a significant interaction between smoking and APOE4 in those with FHCHD p = 0.001. These data demonstrate the complex interaction between genetic and environmental factors in determining CHD risk, and suggest that the causes of the familial clustering of CHD remain largely unexplained.

Family history, longevity, and risk of coronary heart disease: the PRIME Study

BACKGROUND

To assess the contribution of family history of coronary heart disease (CHD) and longevity in parents to 5-year incidence of coronary events in middle-aged men.

METHODS

A prospective study in men from Northern Ireland and the French cities and environs of Lille, Strasbourg, and Toulouse. A total of 10 600 men aged 50-59 years were examined between 1991 and 1994 and followed annually by questionnaire for incident cases of coronary disease. A detailed family history was taken and a quantitative family risk score for CHD was calculated for each subject. Five-year follow-up is complete; all coronary events (coronary deaths, myocardial infarction, and angina) documented by clinical records were reviewed by an independent medical committee.

RESULTS

At screening, 9758 subjects were free of clinical and historical evidence of CHD; in this group there were 317 coronary events by 5 years of follow-up. Subjects whose parents had both survived until >/=80 years showed a relative odds of 0.49 (95% CI: 0.31-0.77) for risk of a coronary event compared with subjects whose parents had not survived until >/=80 years old with adjustment for age and nine other risk factors including family history. The pattern of results was similar in France and Northern Ireland, although parental survival was longer in France. Likewise, subjects with a strong family history showed a relative odds of 1.93 (95% CI: 1.25-3.00) compared with subjects without such a history, after adjustment for age and the nine risk factors including parental longevity. The pattern of results was similar in France and Northern Ireland.

CONCLUSIONS

These results indicate that a family history of coronary disease and parental longevity, although related, act independently of one another and of other major cardiovascular risk factors in predicting 5-year risk of subsequent coronary events.

Family-centered approaches to understanding and preventing coronary heart disease

Family history represents the contributions and interactions of unique genomic and ecologic factors that affect the metabolic profile and life course of a family and its members. It is well known that a family history of coronary heart disease (CHD) is a significant predictor of an individual's risk for CHD even after adjusting for an individual's own established risk factors, such as hypertension, smoking, and abnormal lipoprotein levels. The explanation for the observed familial disease aggregation is not well understood except for the general knowledge that genetic and environmental factors predisposing to CHD also aggregate in families. Given the multifactorial nature of an individual's risk, it can be argued that an individual's familial risk of disease may, in fact, be a better indicator of the many complex interactions among predisposing genetic and environmental factors than can be captured by an individual's own risk factors. Issues of how to assess, quantitate, and apply family history information in clinical settings still need to be resolved. Some clinical risk indicators, such as the National Cholesterol Education Program III guidelines, take into account family history, while others, such as the Framingham Risk Score, do not. Moreover, several family-centered intervention studies have demonstrated the particular advantages of focusing on families rather than just individuals. Although there has been tremendous progress in primary prevention of CHD over the last 20 years, substantial advancements may still be achieved by focusing on the family as its own unit of inference and as a specific target for disease prevention.

The effects of errors in lipid measurement and assessment

Accurate cholesterol and lipoprotein measurements have provided dependable and powerful basic risk factors for cardiovascular disease. A battery of total cholesterol (TC), high-density lipoprotein (HDL) and low-density lipoprotein (LDL) cholesterol, and triglycerides (TG) is recommended in the initial evaluation for classification of patients (based on lipids) into highly desirable, desirable, borderline, high, and very high lipid risk factor for cardiovascular disease. Treatment is based largely on the LDL cholesterol measurement result of the patient. The risk factor score of a patient greatly increases when other risk factors for cardiovascular disease exist, along with increased lipid risk factors. Attainment of the needed acceptable accurate lipid and lipoprotein measurements depends upon prevention or control of multiple sources of errors or variation that can exist in preanalytic, analytic, and postanalytic stages of determination of the reported result. Highly important is to control nonfasting, posture, diet, and alcohol intake in the preanalytic part, elimination of matrix effects and use of accurate calibrators in the analytic part, and check for transcription errors in preparation of reports in the postanalytic part of the measurement of lipids.

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.

Heritability of death from coronary heart disease: a 36-year follow-up of 20 966 Swedish twins

OBJECTIVE

The aim of the present study was to evaluate and distinguish between environmental and genetic effects for death from coronary heart disease (CHD) as well as to determine whether the importance of genetic influences is changing with age.

DESIGN

A cohort study with a follow-up time of 36 years.

SUBJECTS

The cohort drawn for the present study includes 20 966 twins born in Sweden between 1886 and 1925 where both twins within a pair still lived within the country in 1961.

METHODS

Concordances and correlated gamma-frailty model were used to assess and distinguish between genetic and environmental influences as well as to evaluate age-related changes in genetic influences.

RESULTS

A total number of 4007 CHD-deaths (2208 males, and 1799 females) was observed. The probability of dying from CHD given that one's twin partner already has died from CHD decreased with increasing age, particularly amongst males. The genetic variation in susceptibility to death from CHD was moderately large, and decreased slightly across time, particularly amongst males. The heritability was 0.57 (95% CI, 0.45-0.69) amongst male twins, and 0.38 (0.26-0.50) amongst female twins.

CONCLUSIONS

The genetic contribution to the variation in CHD-mortality was moderate both in females and males. Furthermore, although genetic effects appeared to be greater at younger ages of death, our findings clearly suggest that genetic factors are in operation throughout the entire life span.