Serum triglycerides as a risk factor for cardiovascular diseases in the Asia-Pacific region

Apolipoprotein E and lipoprotein lipase gene polymorphisms interaction on the atherogenic combined expression of hypertriglyceridemia and hyperapobetalipoproteinemia phenotypes

The combination of hypertriglyceridemia (hyperTG) and hyperapobetalipoproteinemia (hyperapoB) is associated with an increased coronary artery disease (CAD) risk. Apolipoprotein (apo) E and lipoprotein lipase (LPL) genes are involved in the catabolism of triglycerides (TG)-rich apoB-containing lipoproteins (VLDL). Several apoE and LPL gene variants affecting CAD risk, plasma TG or apoB concentrations have an allelic frequency of >5% in the general population. This study examined the combined effect of frequent apoE and LPL gene polymorphisms on the expression of hyperTG and hyperapoB. ApoE (E2, E3, and E4) and LPL (D9N, N291S, G188E, and P207L) were genotyped and fasting lipid profiles were assessed among 1,441 French-Canadian subjects. Multivariate analyses were performed to estimate the relationship between apoE and LPL gene variants and the risk of hyperTG (TG>1.7 mmol/l) and hyperapoB (apoB>0.9 g/l). Compared to apoE3 carriers, the apoE4 allele significantly increased the risk of expressing the "hyperTG/hyperapoB" phenotype [odds ratio (OR)=1.95; p=0.014]. This risk was significantly exacerbated (OR=4.69; p=0.017) by the presence of frequent deleterious LPL gene variants in this population. The apoE2 allele was negatively associated with hyperTG/hyperapoB (OR=0.49; p=0.002) in the absence of a deleterious LPL gene variant. These results suggest that epistasis is a phenomenon to consider while assessing the CAD risk associated with gene variants or the effect of frequent alleles on high-risk lipid profiles.

Insulin resistance is associated with hypercortisolemia in Polynesian patients treated with antipsychotic medication

OBJECTIVE

Type 2 diabetes is more prevalent in the indigenous Polynesian population of New Zealand (Maori) than in Europeans. The aim of this study was to determine whether insulin resistance in Maori psychiatric patients was associated with antipsychotic treatment and to investigate the mechanism of an association.

RESEARCH DESIGN AND METHODS

Thirty adult Maori psychiatric patients receiving antipsychotic medication for >6 months and 30 healthy, age-, sex-, and BMI-matched control subjects were enrolled. Early morning fasting blood samples were analyzed for plasma levels of glucose, insulin, A1C, triglycerides, total cholesterol, IGF-1, cortisol, cortisol-binding globulin (CBG), and adiponectin.

RESULTS

The patient group had significantly higher median fasting insulin plasma levels than the control group (P = 0.002), which were independent of BMI, age, and sex. In addition, the patient group had significantly higher total cortisol (P = 0.03) and lower CBG levels (P = 0.004) than the control group, resulting in significantly higher levels of free cortisol (P = 0.004). The patient group was also significantly more hypoglycemic (P = 0.026) and hypertriglyceridemic (P = 0.028) than the control group. There was no significant difference in BMI, waist circumference, A1C, total cholesterol, IGF-1, or adiponectin levels between the two groups.

CONCLUSIONS

An increase in insulin resistance is seen in Maori psychiatric patients treated with antipsychotic medication. Therefore, Polynesian ethnicity should be considered in prescribing practice and general care of this group. In addition, the hypothalamic-pituitary-adrenal axis may have an important role in the mechanism by which this insulin resistance develops.

Decrease in blood triglycerides associated with the consumption of eggs of hens fed with food supplemented with fish oil

BACKGROUND

n-3 polyunsaturated fatty acids (n-3 PUFA) convey several health benefits, including a reduction of serum concentration of triglycerides (TG).

AIM

To examine the effect on blood lipids, particularly TG, of a diet with n-3 PUFA enriched eggs in healthy volunteers in the Seychelles (Indian Ocean).

METHODS

Double-blind crossover trial with one group of volunteers fed with 5 normal eggs per week during 3 weeks followed by 5 enriched eggs per week during the next 3 weeks while the other group received eggs in the inverse sequence. Hen feed was supplemented at 5% with tuna oil. Enriched eggs contained nine times more n-3 PUFA than usual eggs (mainly docosahexaenoic acid).

RESULTS

Twenty-five healthy volunteers participated in the study. Based on pooled results observed during the two 3-week periods, consumption of enriched eggs was associated with a significant 16-18% decrease in serum triglycerides (P<0.01) but with no significant difference in serum LDL-cholesterol and HDL-cholesterol. Serum LDL-cholesterol increased during the first 3-week period and decreased during the second 3-week period with both normal and enriched eggs. Participants did not report a systematic preference for either type of eggs.

CONCLUSIONS

Reasonable consumption of n-3 PUFA enriched eggs was associated with a significant decrease in serum triglycerides. These eggs could be a palatably acceptable source of n-3 PUFA.

Triglycerides and the risk of coronary heart disease: 10,158 incident cases among 262,525 participants in 29 Western prospective studies

BACKGROUND

Many epidemiological studies have reported on associations between serum triglyceride concentrations and the risk of coronary heart disease, but this association has not been reliably quantified. In the present study, we report 2 separate nested case-control comparisons in 2 different prospective, population-based cohorts, plus an updated meta-analysis of 27 additional prospective studies in general Western populations.

METHODS AND RESULTS

Measurements were made in a total of 3582 incident cases of fatal and nonfatal coronary heart disease and 6175 controls selected from among the 44,237 men and women screened in the Reykjavik and the European Prospective Investigation of Cancer (EPIC)-Norfolk studies. Repeat measurements were obtained an average of 4 years apart in 1933 participants in the EPIC-Norfolk Study and an average of 12 years apart in 379 participants in the Reykjavik study. The long-term stability of log-triglyceride values (within-person correlation coefficients of 0.64 [95% CI, 0.60 to 0.68] over 4 years and 0.63 [95% CI, 0.57 to 0.70] over 12 years) was similar to those of blood pressure and total serum cholesterol. After adjustment for baseline values of several established risk factors, the strength of the association was substantially attenuated, and the adjusted odds ratio for coronary heart disease was 1.76 (95% CI, 1.39 to 2.21) in the Reykjavik study and 1.57 (95% CI, 1.10 to 2.24) in the EPIC-Norfolk study in a comparison of individuals in the top third with those in the bottom third of usual log-triglyceride values. Similar overall findings (adjusted odds ratio, 1.72; 95% CI, 1.56 to 1.90) were observed in an updated meta-analysis involving a total of 10,158 incident coronary heart disease cases from 262,525 participants in 29 studies.

CONCLUSIONS

Available prospective studies in Western populations consistently indicate moderate and highly significant associations between triglyceride values and coronary heart disease risk. Because these associations depend considerably on levels of established risk factors, however, further studies are needed to help assess the nature of any independent associations.

The influence of estimated creatinine clearance on plasma homocysteine in hypertensive patients with normal serum creatinine

OBJECTIVES

To examine the relation of estimated creatinine clearance (eCrCl) and plasma total homocysteine (tHcy) in hypertensive patients with a normal serum creatinine level.

DESIGN AND METHODS

A total of 137 hypertensive patients (mean age 66.6 years, 69 men) with serum creatinine level </=1.5 mg/dL gave 10-h fasting blood samples for measurement of tHcy, serum folic acid, and serum vitamin B(12).

RESULTS

95 patients fell into a chronic renal insufficiency (CRI) group (eCrCl< or =60 mL/min/1.73 m(2)) and 42 into a normal renal function (NRF) group (eCrCl>60 mL/min/1.73 m(2)). The CRI group was older (p<0.001), had higher tHcy (p<0.001), higher serum urea nitrogen (p<0.001), higher serum creatinine (p<0.001), lower eCrCl (p<0.001), and lower diastolic blood pressure (p=0.001). In univariate analysis, eCrCl had the strongest correlation with tHcy (r=-0.453, p<0.001). Significant correlations, ranging in decreasing order from r=-0.418, p<0.001 to r=-0.170, p=0.047, were also noted between tHcy and twelve other variables. In multivariate analysis, only eCrCl (p<0.001), usage of fibrate (p<0.001), serum level of vitamin B(12) (p=0.002), serum level of folic acid (p=0.009), and smoking (p=0.027) were independent predictors of tHcy.

CONCLUSION

eCrCl is a strong independent predictor of tHcy in hypertensive patients with normal serum creatinine.

An evaluation of metabolic risks for coronary death in the Asia Pacific region

AIM

To investigate the generalizability of current definitions of the metabolic syndrome in Asia-Pacific populations, and whether information on metabolic risk factors could be better used to discriminate fatal coronary heart disease (CHD) risk.

METHODS AND RESULTS

Analyses were performed on individual participant data from 26 cohorts involving 329, 166 participants from the Asia Pacific region. Sensitivity and specificity estimates for CHD death associated with cut-points as defined by the U.S. National Cholesterol Education Panel (NCEP) were determined for component risk factors of a modified NCEP-defined metabolic syndrome. Five cohorts (6437 subjects, 53 CHD deaths) measuring all five risk factors at baseline were used to evaluate the association between the metabolic syndrome and CHD, and to compare risk discrimination using a definition including each risk factor as a continuous variable. Sensitivity and specificity estimates for risk factor cut-points varied considerably by region (Asia versus Australia/New Zealand) and moderately by sex. The adjusted hazard ratio for CHD death associated with the modified NCEP-defined metabolic syndrome was 2.05 (95%CI, 1.13-3.72). On receiver operator characteristic analysis, the area-under-the-curve for CHD death was 0.586 (95%CI: 0.439-0.732) for the modified NCEP-defined metabolic syndrome, and 0.733, 95%CI: 0.664-0.802) for a definition including each of the metabolic risk factors in their continuous form.

CONCLUSION

Specific cut-points for metabolic risk factors are not generalizable between populations. This finding is not restricted to measures of central obesity. A multivariable definition of the metabolic syndrome including all risk factors as continuous variables improves CHD risk discrimination substantially.

Micronized fenofibrate: a useful choice for the correction of dyslipidemia in metabolic syndrome and Type 2 diabetes

Cardiovascular disease is the principal cause of illness and disability in patients with diabetes, and is also the most common cause of death worldwide in adults. Fenofibrate, a member of the fibrate class of lipid-modifying drugs, is a potent triglyceride-lowering and high-density lipoprotein cholesterol-raising agent and has a variable effect on low-density lipoprotein cholesterol. Fenofibrate administration also leads to a modified, less atherogenic low-density lipoprotein profile, with a consistent effect toward increased low-density lipoprotein particle size and a reduction in the low-density lipoprotein particle density. Maximal clinical efficacy in fibrates has been demonstrated in subjects with dyslipidemia, particularly in populations with features of the metabolic syndrome and in patients with Type 2 diabetes. Angiographic data from the Diabetes Atherosclerosis Intervention Study (DAIS) support a similar effect of fenofibrate. However, in the recent Fenofibrate Intervention and Event Lowering in Diabetes trial (FIELD; 9795 patients with Type 2 diabetes), the rate of nonfatal macrovascular events, after adjustment for the use of other lipid-lowering agents and significant reductions in microvascular complications, was lower for the fenofibrate treatment group. These results and those from a current large trial, ACtion to COntrol cardiovascular Risk in Diabetes (ACCORD), will provide valuable evidence for the likely future use of this drug in combination with statins for reducing cardiovascular disease risk in the metabolic syndrome and in Type 2 diabetes.

Antisense oligonucleotides as therapeutics for hyperlipidaemias

Hyperlipidaemia, due to elevations of low-density lipoprotein cholesterol (LDL-C) or triglycerides (TGs), is recognised as a significant risk factor contributing to the development of coronary heart disease (CHD), the leading cause of morbidity and mortality in the Western world. Even though a variety of established antihyperlipidaemic agents are available, the majority of high-risk patients do not reach their lipid goals, indicating the need for new and more effective therapeutics to be used alone or as combination agents with existing drugs. Antisense oligonucleotides (ASOs), designed to specifically and selectively inhibit novel targets involved in cholesterol/TG homeostasis, represent a new class of agents that may prove beneficial for the treatment of hyperlipidaemias resulting from various genetic, metabolic or behavioural factors. This article describes the antisense technology platform, highlights the advantages of these novel drugs for the treatment of hyperlipidaemia and reviews the current research in this area.

Risk scoring in the assessment of cardiovascular risk

PURPOSE OF REVIEW

Cardiovascular risk scoring is incorporated in guidelines and recommended for targeting preventive treatment. Evidence is required on the most appropriate method, its accuracy in a given population, and its effectiveness in favourably influencing clinical behaviour and health outcomes.

RECENT FINDINGS

Recent risk scores address inaccuracies that arise when methods are transferred between populations, and specific methods and recalibrations are described for use in low-risk populations. Ethnic and social differences in risk are also recognized in the context of cardiovascular risk scoring. More sensitive measures of known risk factors and numerous emerging risk factors are reported and new statistical methods and sources of data suggested. Little emphasis has been placed on evaluation of the clinical effectiveness of cardiovascular risk scores. Education in cardiovascular risk assessment may help improve uptake of methods by healthcare professionals.

SUMMARY

Numerous risk scoring methods are available to the healthcare professional but use is patchy. Accuracy varies between populations and methods have been developed to compensate for some of this variability. If risk scoring methods are to be widely used in general practice, evidence is required on both the accuracy of methods in appropriate populations and their effectiveness in improving health outcomes.

Coronary risk prediction for those with and without diabetes

BACKGROUND

Coronary risk prediction 'engines' are now in common use, and their worth is well proven. There remains the question of how to deal with a prior diagnosis of diabetes.

DESIGN

An individual participant meta-analysis of 33 cohort studies involving 364 566 subjects.

METHODS

Fatal coronary hazard ratios for age, smoking, systolic blood pressure and cholesterol, were computed from Cox models, comparing those with and without diabetes. Three risk prediction equations were compared: a 'stepped model', which included the risk factors and diabetes status; an 'interaction model', which included interactions between diabetes and the risk factors; and a 'fixed model', which fixed the 10-year rate of coronary death amongst those with diabetes to be 7%. These were compared through the area under the receiver operating characteristic curve (AUC) and Hosmer-Lemeshow statistics.

RESULTS

The hazard ratio for age was greater for those without diabetes than those with, for men (P=0.005) and women (P=0.02); for men only, systolic blood pressure showed a similar differential (P=0.011). Nevertheless, AUCs were only 0.001 different for the stepped and interaction models for each sex. The AUC for the fixed model was lower and, unlike the other two, showed significant lack of fit for both sexes (P<0.001).

CONCLUSIONS

There is no justification for developing separate risk prediction models for those with and without diabetes, nor for assuming that everyone with diabetes should be considered as being at a common high level of risk. Diabetes status might, instead, be used as a risk variable in an overall population equation.

A comparison of the associations between risk factors and cardiovascular disease in Asia and Australasia

BACKGROUND

Cardiovascular disease is already the leading cause of death in many Asian populations. Relationships between vascular risk factors and cardiovascular disease may differ in Asian and western populations. Previously, a lack of prospective data has prevented the reliable quantification of such differences, which, if they were shown to exist, would suggest that novel cardiovascular prevention and treatment strategies are required for Asia.

DESIGN

An individual participant data meta-analysis of 32 studies from the Asia-Pacific region involving 331 100 subjects (75% from Asia; 25% from the predominantly Caucasian populations of Australia and New Zealand).

METHODS

Outcomes were death from coronary heart disease, ischaemic and haemorrhagic stroke. Hazard ratios were estimated from Cox models for systolic blood pressure (SBP), total cholesterol, triglycerides, body mass index, diabetes and current cigarette smoking, stratified by study and sex and adjusted for age, the other risk factors and regression dilution.

RESULTS

After an average period of follow-up of 4 years there were 2082 deaths from coronary heart disease, 600 from haemorrhagic stroke and 420 from ischaemic stroke. The direction and strength of the associations between risk factors and cardiovascular outcomes were similar in the two regions, although in two cases there were significant differences. Triglycerides were more strongly associated with coronary heart disease in Australia and New Zealand (P = 0.03), whereas SBP showed a stronger relationship with haemorrhagic stroke in Asia (P = 0.04).

CONCLUSIONS

Classical vascular risk factors act similarly in Asian and Caucasian populations; prevention and treatment strategies should thus be similar. Blood pressure reduction should be particularly effective in Asia.

Treatment of Hyperlipidemia from Japanese Evidence

The treatment of hyperlipidemia is aimed at preventing cardiovascular disease (CVD) and coronary heart disease (CHD). As the incidence of CHD in Japan is about one-third lower and that of stroke is two-fold higher compared to Western countries, and the doses of lipid-lowering drugs used in foreign randomized controlled clinical trials (RCTs) are much higher than in general use in Japan, it remains unclear whether the results of RCTs conducted in Western countries could be extrapolated to Japanese patients. Recently, two major large-scale, prospective, RCTs in Japanese hypercholesterolmic patients, the Management of Elevated Cholesterol in the Primary Prevention of Adult Japanese (MEGA) study and the Japan EPA Lipid Intervention Study (JELIS), have been reported. Japanese epidemiological studies and Japanese clinical studies are reviewed. The evidence suggests that hypercholesterolemia, hypertriglyceridemia, and low HDL-cholesterol are strongly associated with increased CHD risk. Lipid-lowering medication shows beneficial effects even in low-risk populations; however, the data did not support that lower cholesterol is better. The safety and efficacy of hyperlipidemia treatment in Japanese patients are discussed.

Coordinated alteration of hepatic gene expression in fatty acid and triglyceride synthesis in LCAT-null mice is associated with altered PUFA metabolism

Complete lecithin:cholesterol acyltransferase (LCAT) deficiency is associated with fasting hypertriglyceridemia (HTG). We recently reported that, in ldlr(-/-)xlcat(-/-) mice, fasting HTG is associated with hepatic triglyceride overproduction in association with an upregulation of the hepatic srebp1 gene and altered expression of its target genes in lipogenesis and gluconeogenesis. We further investigated the role of hepatic polyunsaturated fatty acid (PUFA) metabolism in the modulation of the lipid phenotypes. In the ldlr(-/-)xlcat(-/-) mice, using the ldlr(-/-)xlcat(+/+) littermate as controls, the hepatic level of cholesterol esters (CE) were reduced by 61.0% whereas the 20:4-CE and 22:6-CE contents were each reduced by >80%. In contrast, the hepatic levels of 20:4- and 22:6-containing phospholipid (PL) species were either unchanged or mildly elevated. Similar alterations of the hepatic PUFA in CE and in PL were also observed in the lcat(-/-) mice compared with their wild-type controls. In ldlr(-/-)xlcat(-/-) mice, hepatic mRNA level was markedly reduced for Delta-6 desaturase (fads2) (70.2%) and acyl-CoA:cholesterol acyltransferase-2 (soat2) (57.0%). A similar pattern of gene expression change was also observed in the lcat(-/-) single-knockout mice. In contrast, the acyl-CoA:diacylglycerol acyltransferase-2 (dgat2) mRNA level was 1.7-fold upregulated in the double-knockout mice. In summary, we observed coordinated alterations in hepatic expression of the gene for fads2, soat2, and dgat2, resulting in a reduction in total hepatic PUFA pool and differentially in the PUFA-CE pool, in association with an increase in dgat2 gene expression for promoting triglyceride synthesis and secretion. Some of the phenotypes are not readily explained by known mechanisms and may represent novel regulatory pathways.

Triglycerides + high-density-lipoprotein-cholesterol dyslipidaemia, a coronary risk factor in elderly women: the CArdiovascular STudy in the ELderly

BACKGROUND

The relationship between serum triglycerides (TG) level and the risk of coronary heart disease (CHD) mortality remains controversial.

AIMS

To evaluate whether TG level is a risk factor for CHD in elderly people from general population, and to look for interactions between TG and other risk factors.

METHODS

3257 subjects aged >or= 65 years followed up for 12 years from the CArdiovascular STudy in the ELderly. Blood tests and anthropometric measurements were performed. Continuous items were divided into quintiles and, for each quintile, adjusted hazard ratio (HR) with 95% confidence interval (CI) for CHD mortality was derived by genders from Cox analysis.

RESULTS

In women, the HR of being in the fifth rather than in the first quintile of TG was 2.45 (CI 1.48-3.51). In turn, high-density-lipoprotein cholesterol (HDL-C) inversely predicted CHD mortality; the HR of being in the first rather than in the fifth quintiles of HDL-C was 1.52 (CI 1.24-2.36). The risk of CHD mortality further increased up to 3.81 (CI 1.62-5.43) when high TG and low HDL-C were combined. No predictive role for either TG or HDL-C was detected in men.

CONCLUSIONS

TG and HDL-C were independent predictors of CHD mortality in elderly women. The combination high TG + low HDL-C quadrupled the risk of CHD mortality in this gender only.

A Comparison of Lipid Variables as Predictors of Cardiovascular Disease in the Asia Pacific Region

PURPOSE

Many guidelines advocate measurement of total or low density lipoprotein cholesterol (LDL), high density lipoprotein cholesterol (HDL), and triglycerides (TG) to determine treatment recommendations for preventing coronary heart disease (CHD) and cardiovascular disease (CVD). This analysis is a comparison of lipid variables as predictors of cardiovascular disease.

METHODS

Hazard ratios for coronary and cardiovascular deaths by fourths of total cholesterol (TC), LDL, HDL, TG, non-HDL, TC/HDL, and TG/HDL values, and for a one standard deviation change in these variables, were derived in an individual participant data meta-analysis of 32 cohort studies conducted in the Asia-Pacific region. The predictive value of each lipid variable was assessed using the likelihood ratio statistic.

RESULTS

Adjusting for confounders and regression dilution, each lipid variable had a positive (negative for HDL) log-linear association with fatal CHD and CVD. Individuals in the highest fourth of each lipid variable had approximately twice the risk of CHD compared with those with lowest levels. TG and HDL were each better predictors of CHD and CVD risk compared with TC alone, with test statistics similar to TC/HDL and TG/HDL ratios. Calculated LDL was a relatively poor predictor.

CONCLUSIONS

While LDL reduction remains the main target of intervention for lipid-lowering, these data support the potential use of TG or lipid ratios for CHD risk prediction.