Application of new cholesterol guidelines to a population-based sample

BACKGROUND

The 2013 guidelines of the American College of Cardiology and the American Heart Association (ACC-AHA) for the treatment of cholesterol expand the indications for statin therapy for the prevention of cardiovascular disease.

METHODS

Using data from the National Health and Nutrition Examination Surveys of 2005 to 2010, we estimated the number, and summarized the risk-factor profile, of persons for whom statin therapy would be recommended (i.e., eligible persons) under the new ACC-AHA guidelines, as compared with the guidelines of the Third Adult Treatment Panel (ATP III) of the National Cholesterol Education Program, and extrapolated the results to a population of 115.4 million U.S. adults between the ages of 40 and 75 years.

RESULTS

As compared with the ATP-III guidelines, the new guidelines would increase the number of U.S. adults receiving or eligible for statin therapy from 43.2 million (37.5%) to 56.0 million (48.6%). Most of this increase in numbers (10.4 million of 12.8 million) would occur among adults without cardiovascular disease. Among adults between the ages of 60 and 75 years without cardiovascular disease who are not receiving statin therapy, the percentage who would be eligible for such therapy would increase from 30.4% to 87.4% among men and from 21.2% to 53.6% among women. This effect would be driven largely by an increased number of adults who would be classified solely on the basis of their 10-year risk of a cardiovascular event. Those who would be newly eligible for statin therapy include more men than women and persons with a higher blood pressure but a markedly lower level of low-density lipoprotein cholesterol. As compared with the ATP-III guidelines, the new guidelines would recommend statin therapy for more adults who would be expected to have future cardiovascular events (higher sensitivity) but would also include many adults who would not have future events (lower specificity).

CONCLUSIONS

The new ACC-AHA guidelines for the management of cholesterol would increase the number of adults who would be eligible for statin therapy by 12.8 million, with the increase seen mostly among older adults without cardiovascular disease. (Funded by the Duke Clinical Research Institute and others.).

Proportion of US adults potentially affected by the 2014 hypertension guideline

IMPORTANCE

The new 2014 blood pressure (BP) guideline released by the panel members appointed to the Eighth Joint National Committee (JNC 8; 2014 BP guideline) proposed less restrictive BP targets for adults aged 60 years or older and for those with diabetes and chronic kidney disease.

OBJECTIVE

To estimate the proportion of US adults potentially affected by recent changes in recommendations for management of hypertension.

DESIGN

Cross-sectional, nationally representative survey.

PARTICIPANTS

Using data from the National Health and Nutrition Examination Survey between 2005 and 2010 (n = 16,372), we evaluated hypertension control and treatment recommendations for US adults.

MAIN OUTCOMES AND MEASURES

Proportion of adults estimated to meet guideline-based BP targets under the 2014 BP guideline and under the previous seventh Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure (JNC 7) guideline.

RESULTS

The proportion of younger adults (18-59 years) with treatment-eligible hypertension under the JNC 7 guideline was 20.3% (95% CI, 19.1%-21.4%) and decreased to 19.2% (95% CI, 18.1%-20.4%) under the 2014 BP guideline. Larger declines were observed among older adults (≥60 years), decreasing from 68.9% (95% CI, 66.9%-70.8%) under JNC 7 to 61.2% (95% CI, 59.3%-63.0%) under the 2014 BP guideline. The proportion of adults with treatment-eligible hypertension who met BP goals increased slightly for younger adults, from 41.2% (95% CI, 38.1%-44.3%) under JNC 7 to 47.5% (95% CI, 44.4%-50.6%) under the 2014 BP guideline, and more substantially for older adults, from 40.0% (95% CI, 37.8%-42.3%) under JNC 7 to 65.8% (95% CI, 63.7%-67.9%) under the 2014 BP guideline. Overall, 1.6% (95% CI, 1.3%-1.9%) of US adults aged 18-59 years and 27.6% (95% CI, 25.9%-29.3%) of adults aged 60 years or older were receiving BP-lowering medication and meeting more stringent JNC 7 targets. These patients may be eligible for less stringent or no BP therapy with the 2014 BP guideline.

CONCLUSIONS AND RELEVANCE

Compared with the JNC 7 guideline, the 2014 BP guideline from the panel members appointed to the JNC 8 was associated with a reduction in the proportion of US adults recommended for hypertension treatment and a substantial increase in the proportion of adults considered to have achieved goal BP, primarily in older adults.

Calculation of LDL apoB

OBJECTIVES

This study tests the validity of the Hattori formula to calculate LDL apoB based on plasma lipids and total apoB.

METHODS

In 2178 patients in a tertiary care lipid clinic, LDL apoB calculated as suggested by Hattori et al. was compared to directly measured LDL apoB isolated by ultracentrifugation.

RESULTS

In subjects with plasma triglycerides ≥ 3.0 mmol/L, there was considerable discordance between calculated and measured LDL apoB. In all others, the relation between measured LDL apoB and calculated LDL apoB could be expressed as LDL apoB = 0.86 [total apoB - 0.9 TC (mg/dL) + 0.09 HDL-C (mg/dL) - 0.08 TG (mg/dL)] - 7.0 (r > 0.91; P < 0.0001).

CONCLUSIONS

Our results indicate that LDL apoB can be calculated with reasonable accuracy when triglycerides are <3.0 mmol/L. However, the calculation suggested by Hattori et al. should be corrected based on the regression demonstrated between calculated and measured LDL apoB in subjects with a plasma triglyceride <3.0 mmol/L.

The severe hypercholesterolemia phenotype: clinical diagnosis, management, and emerging therapies

The severe hypercholesterolemia phenotype includes all patients with marked elevation of low-density lipoprotein cholesterol (LDL-C) levels. The most common cause is autosomal dominant hypercholesterolemia, an inherited disorder caused by mutations either in LDL receptor, apolipoprotein B (APOB), or proprotein convertase subtilisin kexin type 9 (PCSK9) genes. However, it is now known that many subjects with severe inherited hypercholesterolemia have no defects in these genes. These cases are caused either by mutations in genes yet to be identified or are consequences of polygenic, epigenetic, or acquired defects. Because the clinical consequences of extreme hypercholesterolemia are the same no matter the cause, the focus should be on the identification of subjects with severe hypercholesterolemia, followed by phenotypic screening of family members. Genetic screening is not necessary to diagnose or initiate treatment for the severe hypercholesterolemia phenotype. Management of severe hypercholesterolemia is based on risk factor modification and use of multiple lipid-lowering medications. Lipoprotein apheresis is indicated for coronary artery disease (CAD) patients taking maximally tolerated therapy and with LDL-C levels >200 mg/dl (>300 mg/dl if without CAD). A microsomal triglyceride transfer protein inhibitor and an antisense oligonucleotide against APOB have recently been approved for use in subjects with clinically diagnosed homozygous familial hypercholesterolemia. PCSK9 inhibitors, currently in phase II and III trials, lower LDL-C up to an additional 70% in the setting of maximally tolerated medical therapy and have the potential to reduce LDL-C to <70 mg/dl in most patients. Early identification of affected individuals and aggressive treatment should significantly reduce the burden of cardiovascular disease in society.

Elevated troponin I levels but not low grade chronic inflammation is associated with cardiac-specific mortality in stable hemodialysis patients

BACKGROUND

Elevated cardiac troponin I (TnI) levels are associated with all-cause mortality in stable hemodialysis patients. Their relationship to cardiac-specific death has been inconsistent, and the reason for their elevation is not well understood. We hypothesized that elevated TnI levels in chronic stable hemodialysis patients more specifically track with cardiac mortality, and this mechanism is independent of other contributors of cardiac mortality, such as inflammation.

METHODS

We conducted a single-centre, cohort study of prevalent hemodialysis patients at a tertiary care hospital. Plasma TnI levels were measured with routine monthly blood tests in clinically stable patients for two consecutive months. Plasma TnI was measured by immunoassay and a value above the laboratory reference range (0.06 μg/L) was considered elevated. The primary outcome of death was adjudicated separately for this study, and classified as cardiac, non-cardiac, or unknown. Cox proportional hazard models were used to examine the association of TnI with the all-cause and cardiac-specific mortality, adjusting for potential confounders, including C-reactive protein (CRP) as a marker of inflammation.

RESULTS

Of 133 patients followed for a median of 1.7 years, there were 38 deaths (58% non-cardiac, 39% cardiac, 3% unknown). Elevated TnI was associated with adjusted HR for all-cause mortality of 2.57 (95% CI 1.30-5.09) and an adjusted HR for cardiac death of 3.14 (95% CI 1.07-9.2), after accounting for age, time on dialysis, diabetes status, prior coronary artery disease history, and C-reactive protein. Although CRP was also independently associated with all-cause mortality, it did not add prognostic information to TnI for cardiac-specific death.

CONCLUSION

Elevated TnI levels are independently associated with cardiac and all-cause mortality in asymptomatic hemodialysis patients. The mechanism for this risk is likely independent of inflammation, but may reflect chronic subclinical myocardial injury or unmask those with subclinical atherosclerotic heart disease. Whether those with elevated TnI levels may benefit from additional investigations or more aggressive therapies to treat cardiovascular disease remains to be determined.

The necessity for clinical reasoning in the era of evidence-based medicine

Clinical decisions are increasingly driven by evidence-based recommendations of guideline groups, which aim to be based on the highest quality knowledge-randomized clinical trials (RCTs) and meta-analyses. Although RCTs provide the best assessment of the overall value of a therapy, high-quality evidence from RCTs is often incomplete, contradictory, or absent even in areas that have been most exhaustively studied. Moreover, the likelihood of the success or failure of a therapy is not identical in all the individuals treated in any trial because therapy is not the only determinant of outcome. Therefore, the overall results of a trial cannot be assumed to apply to any particular individual, not even someone who corresponds to all the entry criteria for the trial. In addition, the potential for bias due to financial conflicts remains in many guideline groups. Guidelines are key sources of knowledge. Nevertheless, limitations in the extent, quality, generalizability, and transferability of evidence mean that we clinicians must still reason through the best choices for an individual because even in the absence of full and secure knowledge, clinical decisions must still be made. Clinical reasoning is the pragmatic, tried-and-true process of expert clinical problem solving that does value mechanistic reasoning and clinical experience as well as RCTs and observational studies. Clinicians must continue to value clinical reasoning if our aim is the best clinical care for all the individuals we treat.

Is the superiority of apoB over non-HDL-C as a marker of cardiovascular risk in the INTERHEART study due to confounding by related variables?

BACKGROUND

Patients with increased numbers of cholesterol-depleted apolipoprotein B (apoB) particles frequently have multiple other abnormalities, which might confound the comparison of apoB and non-high-density-lipoprotein-cholesterol (non-HDL-C) as markers of cardiovascular risk.

OBJECTIVE

We wanted to determine whether the superiority of apoB over non-HDL-C as a marker of cardiovascular risk in the INTERHEART study is due to such variables that act as confounders of the primary comparison.

METHODS

To test for confounding, cases and controls were first separated into 3 groups on the basis of the percentile levels within the study of non-HDL-C and apoB with discordance defined as a difference of 5 percentile points. Logistic regression was used to compute odds ratio of myocardial infarction (as an outcome) for different categories, assuming concordance as reference adjusted for other confounders.

RESULTS

Plasma triglyceride and non-HDL-C levels were highest in the discordant group with lowest risk and lowest in the discordant group with highest risk, whereas apoB was highest in the discordant group with the highest risk and lowest in the discordant group with the lowest group. Moreover, no significant change was found in the odds ratio for either discordant group when adjusted for the effect of any of the variables examined, evidence that none confounded the primary comparison.

CONCLUSION

Factors such as hypertriglyceridemia do not confound the comparison of apoB and non-HDL-C, further evidence that apoB is superior to non-HDL-C as a marker of the importance of the apoB atherogenic lipoproteins in cardiovascular risk.

Hepatic cholesterol homeostasis: is the low-density lipoprotein pathway a regulatory or a shunt pathway?

OBJECTIVE

The hypothesis that cholesterol that enters the cell within low-density lipoprotein (LDL) particles rapidly equilibrates with the regulatory pool of intracellular cholesterol and maintains cholesterol homeostasis by reducing cholesterol and LDL receptor synthesis was validated in the fibroblast but not in the hepatocyte. Accordingly, the present studies were designed to compare the effects of cholesterol that enters the hepatocyte within an LDL particle with those of cholesterol that enters via other lipoprotein particles.

APPROACH AND RESULTS

We measured cholesterol synthesis and esterification in hamster hepatocytes treated with LDL and other lipoprotein particles, including chylomicron remnants and VLDL. Endogenous cholesterol synthesis was not significantly reduced by uptake of LDL, but cholesterol esterification (280%) and acyl CoA:cholesterol acyltransferase 2 expression (870%) were increased. In contrast, cholesterol synthesis was significantly reduced (70% decrease) with other lipoprotein particles. Furthermore, more cholesterol that entered the hepatocyte within LDL particles was secreted within VLDL particles (480%) compared with cholesterol from other sources.

CONCLUSIONS

Much of the cholesterol that enters the hepatocyte within LDL particles is shunted through the cell and resecreted within VLDL particles without reaching equilibrium with the regulatory pool.

Do statins lower testosterone and does it matter?

Drugs are two-sided swords and statins are no exception. Schooling et al. demonstrate that, on average, statins produce small, but statistically significant, decreases in testosterone. They appropriately emphasize that the clinical significance of their observations is unclear but suggest that changes in testosterone might be related to the benefits of therapy as well as the risks, such as the increased chance of diabetes mellitus. Their findings and hypotheses are noteworthy. However, we believe this represents another example of the limitations in the published summaries of drug effects. How do we know all changes induced by drugs are normally distributed? Some may be affected much more than others. Moreover, the confidence intervals of a meta-analysis describe the variance of the mean effect, not the range of effects, and while the mean change characterizes the impact of a drug on a group of patients, the range more fully characterizes its effects on individuals. We treat individuals not groups. Averages do not disclose enough about the risks and benefits of drugs. See related research article here http://www.biomedcentral.com/1741-7015/11/57.

Establishing cut-off values for apolipoprotein B and non-HDL-C according to LDL-C values in a South European population

BACKGROUND

Low-density lipoprotein cholesterol (LDL-C) remains the primary target of therapy in most strategies of dyslipidaemia management focused on cardiovascular disease prevention. Different guidelines have identified specific LDL-C cut-off points as targets for therapeutic intervention. Many clinical situations characterised by dyslipidaemia and elevated triglycerides are common in our environment and in overall industrialised countries. Thus, lipid goals based only on LDL-C could misclassify an important percentage of subjects. The objective of the present study was to establish cut-off point values for apoB and non-HDL-C in relation to the identified LDL-C cut-off points for cardiovascular risk in a South European population.

METHODS

We performed a cross-sectional study including 1501 subjects (770 women and 731 men) between 18 and 80 years of age. Samples were collected after 12-14 h of fasting. Cholesterol, HDL-C, triglycerides and apoB levels were measured using direct methods. LDL-C was calculated by the Friedewald formula. Non-HDL-C was calculated as total cholesterol minus HDL-C.

RESULTS

The Spearman's rank correlations between apoB and LDL-C (r 0.86, p < 0.0001), and between apoB and non-HDL-C (r 0.91, p < 0.0001) were both significant. The proposed cut-off points for apoB, according to LDL-C goals (70, 100, 130 and 160 mg/dl) in our population are 70, 80, 100 and 115 mg/dl respectively. The proposed cut-off values for non-HDL-C are 100, 120, 150 and 190 mg/dl respectively.

CONCLUSION

The established LDL-C cut-off values could not be accurate to estimate cardiovascular risk in subjects with mild hypertriglyceridaemia, as frequently occurs in our Mediterranean population. To take into consideration the burden of atherogenic particles and better classify patients at risk we propose cut-off values for apoB or the equivalent for non-HDL-C. Prospective trials including cardiovascular variables are needed to validate our assumption.

Discordance analysis of apolipoprotein B and non-high density lipoprotein cholesterol as markers of cardiovascular risk in the INTERHEART study

OBJECTIVES

Whether non-HDL-C and apoB are equivalent markers of cardiovascular risk remains controversial. Only when apoB particles in toto contain either more or less cholesterol than normal - that is, when their composition is discordant - could apoB and non-HDL-C predict risk differently. Accordingly, this study tests within the INTERHEART data base whether apoB or non-HDL-C are equivalent markers of risk when the two markers are discordant.

METHODS

The INTERHEART study is a standardized case-control study of acute myocardial infarction with blood samples in 9345 cases and 12,120 controls from 52 countries. To produce comparability, the concentrations of non-HDL-C and apoB are expressed as percentiles (P) within the study population. Concordance is defined as the phenotype when P Non-HDL-C = P apoB (that is, apoB particles contain a normal mass of cholesterol). Discordance is defined either as the phenotype when P Non-HDL-C > P apoB (cholesterol-enriched apoB particles) or P Non-HDL-C < P apoB (cholesterol-depleted apoB particles). The OR of cases to controls was determined for both discordant groups and compared to the ratio of cases to controls in the concordant group, which was the reference group. An OR > 1 means that risk is greater in the discordant than in the reference phenotype whereas an OR < 1 means the cases are less common in the discordant phenotype than in the reference group.

RESULTS

When discordance was defined as percentiles within 5%, a definition that produced equal numbers of discordant and concordant individuals, the OR for P Non-HDL-C > apoB (cholesterol-enriched apoB particles) was 0.72 (0.67-0.77 95% CI) indicating risk was less than the reference concordant group whereas the OR for P Non-HDL-C < apoB (cholesterol-depleted apoB particles) was 1.58 (1.38-1.58 95% CI) indicating risk was significantly greater than the reference concordant group. The same findings were reproduced using all definitions of discordance from 1% to 10%. Moreover, the pattern of findings was consistent amongst the ethnic groups that made up the overall study population.

CONCLUSION

Discordance analysis demonstrates that apoB is a more accurate marker of cardiovascular risk than non-HDL-C.

Comparison of coronary calcium screening versus broad statin therapy for patients at intermediate cardiovascular risk

Net reclassification has become widely accepted as a method to demonstrate whether new diagnostic technologies add significantly to the discrimination of risk. However, more accurate categorization of risk does not necessarily result in a better clinical outcome. This study examined whether coronary artery calcium, a technology that improves net reclassification in patients at intermediate risk for cardiovascular events, is superior to a strategy that calls for broader intervention with statin therapy in these patients. To do so, the clinical impact and costs of 2 intervention regimens on outcome in the Multi-Ethnic Study of Atherosclerosis (MESA) were calculated based on the known efficacy of statins. Intervention 1 involved treatment of all subjects at conventional intermediate risk with moderate-dose stain, whereas intervention 2 involved moderate- and high-dose statin therapy, respectively, of those remaining at intermediate risk and those reassigned to high risk after reclassification by coronary artery calcium. The 2 strategies would decrease clinical events by 23% and would produce net savings. However, these would be greater with the broad statin prevention strategy than with the coronary calcium reclassification strategy ($732,152 vs $288,336, respectively). In conclusion, even in the short term, the broad statin prevention strategy would be at least as effective in decreasing clinical events but with greater net savings than a prevention strategy using coronary calcium screening.

The causal exposure model of vascular disease

Primary prevention of cardiovascular disease is governed at present by the risk factor model for cardiovascular events, a model which is widely accepted by physicians and professional associations, but which has important limitations: most critically, that effective treatment to reduce arterial damage is often delayed until the age at which cardiovascular events become common. This delay means that many of the early victims of vascular disease will not be identified in time. This delay also allows atherosclerosis to develop and progress unchecked within the arterial tree with the result that the absolute effectiveness of preventive therapy is limited by the time it is eventually initiated. The causal exposure model of vascular disease is an alternative to the risk factor model for cardiovascular events. Whereas the risk factor model aims to identify and treat those at markedly increased risk of vascular events within the next decade, the causal exposure model of vascular disease aims to prevent events by treating the causes of the disease when they are identified. In the risk factor model, age is an independent non-modifiable risk factor and the predictive power of age far outweighs that of the other risk factors. In the causal exposure model, age is the duration of time the arterial wall is exposed to the causes of atherosclerosis: apoB (apolipoprotein B) lipoproteins, hypertension, diabetes and smoking. Preventing the development of advanced atherosclerotic lesions by treating the causes of vascular disease is the simplest, surest and most effective way to prevent clinical events.

Clinical utility of inflammatory markers and advanced lipoprotein testing: advice from an expert panel of lipid specialists

The National Cholesterol Education Program Adult Treatment Panel guidelines have established low-density lipoprotein cholesterol (LDL-C) treatment goals, and secondary non-high-density lipoprotein (HDL)-C treatment goals for persons with hypertriglyceridemia. The use of lipid-lowering therapies, particularly statins, to achieve these goals has reduced cardiovascular disease (CVD) morbidity and mortality; however, significant residual risk for events remains. This, combined with the rising prevalence of obesity, which has shifted the risk profile of the population toward patients in whom LDL-C is less predictive of CVD events (metabolic syndrome, low HDL-C, elevated triglycerides), has increased interest in the clinical use of inflammatory and lipid biomarker assessments. Furthermore, the cost effectiveness of pharmacological intervention for both the initiation of therapy and the intensification of therapy has been enhanced by the availability of a variety of generic statins. This report describes the consensus view of an expert panel convened by the National Lipid Association to evaluate the use of selected biomarkers [C-reactive protein, lipoprotein-associated phospholipase A(2), apolipoprotein B, LDL particle concentration, lipoprotein(a), and LDL and HDL subfractions] to improve risk assessment, or to adjust therapy. These panel recommendations are intended to provide practical advice to clinicians who wrestle with the challenges of identifying the patients who are most likely to benefit from therapy, or intensification of therapy, to provide the optimum protection from CV risk.

Should preclinical vascular abnormalities be measured in asymptomatic adults to improve cardiovascular risk stratification?

PURPOSE OF REVIEW

Guideline groups have issued contradictory decisions as to the value of noninvasive tests in asymptomatic adults at intermediate cardiovascular risk. Reclassification has only recently been accepted as a critical criterion to determine the utility of a diagnostic test. The present review examines potential limitations in reclassification and evaluates the utility of carotid ultrasound, pulse wave velocity and ankle brachial index from a clinical perspective.

RECENT FINDINGS

Reclassification is less useful than generally believed, because therapy is already indicated in the majority of patients at intermediate risk and it is far from clear that treatment should be withheld in those who are downgraded in risk. Moreover, the additional benefit from more intensive therapy is much less than often thought. Reproducibility, standardization and reference values of noninvasive tests are obligatory before introduction in clinical care.

SUMMARY

Routine screening of all those at intermediate risk does not appear to be justified. Screening should be performed on those individuals in whom the noninvasive test changes clinical care, which is most apparent for individuals at intermediate risk with LDL level less than 2.5 mmol/l, in whom positive noninvasive tests will result in the start of statin treatment. The primary value of these tests should not be to determine risk but to identify preclinical anatomic disease.

Abstract P235: Implications of the Selection of Target Markers for LDL Lowering

Our aim was to compare the implications of targeting LDL-lowering treatment to LDL-C, non-HDL-C, or apoB based on a recent meta-analysis of all published epidemiological studies with all three markers' vascular risk associations which found overall per standard deviation relative risk ratios (RRR) of 1.25 for LDL-C, 1.31 for non-HDL-C, and 1.41 for apoB. Our approach was to project the 10-year incidence of CHD events from NHANES 2005-2006 with 1697 subjects representing over 190 million adult US residents under different scenarios defined by the target marker and the percentage of people treated. Framingham equations were used to estimate each subject's 10-year CHD risk. We estimated each subject's risk if treated by dividing their initial risk estimate by the marker's RRR exponentiated to the number of standard deviations (LDL-C: 35 mg/dl, non-HDL-C: 42 mg/dl, apoB: 27 mg/dl) in 40% of the marker's measured level. The potential number of CHD cases prevented by the treatment was calculated by multiplying the difference between initial and treated risk by the number of people represented. The mean 10-year CHD risk was 7.00% indicating 13.3 million incident CHD cases would be expected over the subsequent 10 years with no treatment change. The expected numbers of incident CHD cases prevented under different treatment scenarios are shown in the figure. These results support recommendations to use apoB in clinical practice to identify candidates for LDL-lowering and to target their treatment.

Reliability of low-density lipoprotein cholesterol, non-high-density lipoprotein cholesterol, and apolipoprotein B measurement

There is little understanding of the reliability of laboratory measurements among clinicians. Low-density lipoprotein cholesterol (LDL-C) measurement is the cornerstone of cardiovascular risk assessment and prevention, but it is fraught with error. Therefore, we have reviewed issues related to accuracy and precision for the measurement of LDL-C and the related markers non-high-density lipoprotein cholesterol (non-HDL-C) and apolipoprotein B. Despite the widespread belief that LDL-C is standardized and reproducible, available data suggest that results can vary significantly as the result of methods from different manufacturers. Similar problems with direct HDL-C assays raise concerns about the reliability of non-HDL-C measurement. The root cause of method-specific bias relates to the ambiguity in the definition of both LDL and HDL, and the heterogeneity of LDL and HDL particle size and composition. Apolipoprotein B appears to provide a more reliable alternative, but assays for it have not been as rigorously tested as direct LDL-C and HDL-C assays.

A meta-analysis of low-density lipoprotein cholesterol, non-high-density lipoprotein cholesterol, and apolipoprotein B as markers of cardiovascular risk

BACKGROUND

Whether apolipoprotein B (apoB) or non-high-density lipoprotein cholesterol (HDL-C) adds to the predictive power of low-density lipoprotein cholesterol (LDL-C) for cardiovascular risk remains controversial.

METHODS AND RESULTS

This meta-analysis is based on all the published epidemiological studies that contained estimates of the relative risks of non-HDL-C and apoB of fatal or nonfatal ischemic cardiovascular events. Twelve independent reports, including 233 455 subjects and 22 950 events, were analyzed. All published risk estimates were converted to standardized relative risk ratios (RRRs) and analyzed by quantitative meta-analysis using a random-effects model. Whether analyzed individually or in head-to-head comparisons, apoB was the most potent marker of cardiovascular risk (RRR, 1.43; 95% CI, 1.35 to 1.51), LDL-C was the least (RRR, 1.25; 95% CI, 1.18 to 1.33), and non-HDL-C was intermediate (RRR, 1.34; 95% CI, 1.24 to 1.44). The overall comparisons of the within-study differences showed that apoB RRR was 5.7%>non-HDL-C (P<0.001) and 12.0%>LDL-C (P<0.0001) and that non-HDL-C RRR was 5.0%>LDL-C (P=0.017). Only HDL-C accounted for any substantial portion of the variance of the results among the studies. We calculated the number of clinical events prevented by a high-risk treatment regimen of all those >70th percentile of the US adult population using each of the 3 markers. Over a 10-year period, a non-HDL-C strategy would prevent 300 000 more events than an LDL-C strategy, whereas an apoB strategy would prevent 500 000 more events than a non-HDL-C strategy.

CONCLUSIONS

These results further validate the value of apoB in clinical care.

Application and validation of a diagnostic algorithm for the atherogenic apoB dyslipoproteinemias: ApoB dyslipoproteinemias in a Dutch population-based study

BACKGROUND

We applied a diagnostic algorithm using apolipoprotein B (apoB) in combination with triglycerides (TG) and total cholesterol to determine the prevalence of dyslipoproteinemias in the general population. We also characterized the overall cardiovascular (CV) risk profiles, including arterial structure and function as measured with a panel of noninvasive parameters.

DESIGN

Clinical and biochemical characteristics and noninvasive measurements of atherosclerosis (NIMA) were determined in 1517 individuals, aged 50-70 years.

RESULTS

In general, all dyslipoproteinemias were characterized by a worse CV risk profile and deteriorated outcomes of NIMA compared to those with normal apolipoprotein B (< 1·2 g L(-1)) and TG (< 1·5 mM) levels. The prevalence of hyperapoB-hyperTG was 15·1%, and these individuals showed the most abnormal atheroma-related parameters: reduced ankle-brachial-index at rest (-3·5%) and after exercise (-9·8%), increased intima-media thickness (+5·5%) and more carotid plaques (+39·1%). The prevalence of normoapoB-hyperTG because of increased VLDL was 18·1% and 2·3% because of increased chylomicrons and VLDL, and in these groups, the parameters related to stiffness (e.g. pulse-wave-velocity +7·6% and +5·2%, respectively) were most abnormal. Adjustment for apolipoprotein B (apoB) reduced differences in NIMA in the hyperapoB-hyperTG group, whereas adjustment for TG reduced differences in NIMA in the normoapoB-hyperTG group.

CONCLUSIONS

The overall prevalence of dyslipoproteinemias according to the algorithm was approximately 40% in the Dutch population. The different dyslipoproteinemias showed a less favourable CV risk profile and deteriorated NIMA parameters, reflecting increased subclinical atherosclerosis. Furthermore, different effects on different NIMA parameters were observed in the different dyslipoproteinemias.

Ethnic-specific differences in abdominal subcutaneous adipose tissue compartments

South Asians have a higher prevalence of cardiovascular disease (CVD) than Europeans. Studies have identified distinct subcompartments of subcutaneous adipose tissue (SAT) that provide insight into the relationship between abdominal obesity and metabolic risk factors in different ethnic groups. Our objective was to determine the relationship between SAT compartments and fat-free mass (FFM) between South Asian and European cohorts, and between men and women. Healthy Europeans and South Asians (n = 408) were assessed for FFM via dual energy X-ray absorptiometry, and SAT areas by computed tomography (CT). SAT was subdivided into superficial subcutaneous abdominal adipose tissue (SSAT) and deep subcutaneous abdominal adipose tissue (DSAT). Linear regression analyses were performed using DSAT and SSAT as separate dependent variables and FFM and ethnicity as primary independent variables adjusting for age, gender, income, education, and smoking status. Results showed that South Asian men had significantly higher amounts of DSAT (median 187.65 cm(2) vs. 145.15 cm(2), P < 0.001), SSAT (median 92.0 cm(2) vs. 76.1 cm(2), P = 0.046), and body fat mass (BFM) (25.1 kg vs. 22.6 kg, P = 0.049) than European men. In a fully adjusted model, South Asians showed significantly greater DSAT at any FFM than Europeans. Women had more SSAT at any given FFM than men and less DSAT at any given FFM than men, irrespective of ethnic background. In conclusion, South Asians had more DSAT than Europeans and men had relatively more DSAT than women. These data suggest that specific fat depots are influenced by ethnicity and gender; therefore, could provide insight into the relationship between ethnicity, gender and subsequent risk for CVD.