Discordance Analysis of VLDL-C and ApoB in UK Biobank and Framingham Study: A Prospective Observational Study.

BACKGROUND: Recent observational and Mendelian randomization analyses have reported significant effects of very-low-density lipoprotein cholesterol (VLDL-C) on risk that is independent of ApoB. OBJECTIVES: To determine the independent association of VLDL-C and ApoB with the risk of new-onset cardiovascular events in the UK Biobank and the Framingham Heart Study Cohort. METHODS: We included 294 289 UK Biobank participants with a median age of 56 years, 42% men, and 2865 Framingham Heart Study participants (median age, 52 years; 47% men). The residual resulting from regressing VLDL-C on ApoB expresses the portion of VLDL-C not explained by ApoB, while the residual from regressing ApoB on VLDL-C expresses the portion of ApoB not explained by VLDL-C. Cox proportional hazards models for atherosclerotic cardiovascular disease incidence were created for residual VLDL-C and residual ApoB. Models were analyzed with and without high-density lipoprotein cholesterol (HDL-C). Furthermore, we investigated the independent effects of VLDL-C after accounting for ApoB and HDL-C and of HDL-C after accounting for ApoB and VLDL-C. RESULTS: In the UK Biobank, ApoB was highly correlated with VLDL-C (r=0.70; P<0.001) but weakly negatively correlated with HDL-C (r=-0.11; P<0.001). The ApoB residual and the VLDL-C residual were significantly associated with new-onset atherosclerotic cardiovascular disease (hazard ratio [HR], 1.08 and 1.06, respectively; P<0.001). After adjusting for HDL-C, the ApoB residual remained similar in magnitude (HR, 1.10; P<0.001), whereas the effect size of the VLDL-C residual was reduced (HR, 1.02; P=0.029). The independent effect of HDL-C (after accounting for ApoB and VLDL-C) remained robust (HR, 0.86; P<0.0001), while the independent effect of VLDL-C (after accounting for ApoB and HDL-C) was modest (HR, 1.02; P=0.029). All results were consistent in the Framingham cohort. CONCLUSIONS: When adjusted for HDL-C, the association of VLDL-C with cardiovascular risk was no longer clinically meaningful. Our residual discordance analysis suggests that adjustment for HDL-C cannot be ignored.

The Causal-Benefit Model to Prevent Cardiovascular Events.

Selecting individuals for preventive lipid-lowering therapy is presently governed by the 10-year risk model. Once a prespecified level of cardiovascular disease risk is equaled or exceeded, individuals become eligible for preventive lipid-lowering therapy. A key limitation of this model is that only a small minority of individuals below the age of 65 years are eligible for therapy. However, just under one-half of all cardiovascular disease events occur below this age. Additionally, in many, the disease that caused their events after 65 years of age developed and progressed before 65 years of age. The causal-benefit model of prevention identifies individuals based both on their risk and the estimated benefit from lowering atherogenic apoB lipoprotein levels. Adopting the causal-benefit model would increase the number of younger subjects eligible for preventive treatment, would increase the total number of cardiovascular disease events prevented at virtually the same number to treat, and would be cost-effective.

Individual Variation in the Distribution of Apolipoprotein B Levels Across the Spectrum of LDL-C or Non-HDL-C Levels.

Importance: Although apolipoprotein B (apoB) is a superior marker of lipid-related risk compared with low-density lipoprotein cholesterol (LDL-C), few data exist to translate the goals and thresholds from LDL-C to their apoB equivalent. In addition, although current American College of Cardiology/American Heart Association guidelines provide a relative indication for apoB measurement among individuals with hypertriglyceridemia, whether discordance is limited to those subgroups is unknown. Objectives: To assess the variability in apoB level across the spectrum of LDL-C or non-high-density lipoprotein cholesterol (non-HDL-C) levels and evaluate whether discordance between apoB and LDL-C or non-HDL-C is limited to specifiable subgroups. Design, Setting, and Participants: This cross-sectional study used data from a nationally representative sample of 12 688 adult participants not using statins in the National Health and Nutrition Examination Survey between 2005 and 2016. Statistical analysis was performed from April 2023 to February 2024. Main Outcomes and Measures: Quantile regression was used to assess the population distribution of apoB across LDL-C or non-HDL-C levels. Discordance between apoB and LDL-C was the difference between measured apoB and median apoB levels for an individual's LDL-C level. Discordance was evaluated by age, sex, race and ethnicity, obesity, diabetes, triglyceride level, hemoglobin A1c level, body mass index (BMI), statin use, and metabolic health (defined as a BMI between 18.5 and 24.9, triglyceride level <150 mg/dL, and no diabetes). Results: Among the sample of 12 688 participants (median age, 41.0 years [IQR, 29.0-54.0 years]; 52.9% women) for LDL-C values of 55, 70, 100, and 190 mg/dL, the corresponding population median apoB levels were 49, 60, 80, and 140 mg/dL, respectively. For given levels of LDL-C, a range of apoB values was observed. At an LDL-C level of 100 mg/dL, the 95% population distribution of apoB ranged from 66 mg/dL to 99 mg/dL. ApoB variability was highest for LDL-C values estimated using the Friedewald equation, lower when using Sampson or Martin-Hopkins equations, and lowest for non-HDL-C. Although individuals with metabolic risk factors were more likely to have discordantly high apoB levels (ie, had higher median observed apoB levels relative to what was estimated based on LDL-C), significant variability in apoB levels was observed even among metabolically healthy individuals. Conclusions and Relevance: This study suggests that even metabolically healthy individuals may have discordantly high apoB levels relative to LDL-C or non-HDL-C levels. The current guideline approach for apoB testing only for those with hypertriglyceridemia appears too narrow. Population percentile data can be used to translate LDL-C goals and thresholds to their apoB equivalent to facilitate clinical adoption.

Discordance among apoB, non-high-density lipoprotein cholesterol, and triglycerides: implications for cardiovascular prevention.

BACKGROUND AND AIMS: Despite growing evidence that apolipoprotein B (apoB) is the most accurate marker of atherosclerotic cardiovascular disease (ASCVD) risk, its adoption in clinical practice has been low. This investigation sought to determine whether low-density lipoprotein cholesterol (LDL-C), non-high-density lipoprotein cholesterol (HDL-C), and triglycerides are sufficient for routine cardiovascular care. METHODS: A sample of 293 876 UK Biobank adults (age: 40-73 years, 42% men), free of cardiovascular disease, with a median follow-up for new-onset ASCVD of 11 years was included. Distribution of apoB at pre-specified levels of LDL-C, non-HDL-C, and triglycerides was examined graphically, and 10-year ASCVD event rates were compared for high vs. low apoB. Residuals of apoB were constructed after regressing apoB on LDL-C, non-HDL-C, and log-transformed triglycerides and used as predictors in a proportional hazards regression model for new-onset ASCVD adjusted for standard risk factors, including HDL-C. RESULTS: ApoB was highly correlated with LDL-C and non-HDL-C (Pearson's r = .96, P < .001 for both) but less so with log triglycerides (r = .42, P < .001). However, apoB ranges necessary to capture 95% of all observations at pre-specified levels of LDL-C, non-HDL-C, or triglycerides were wide, spanning 85.8-108.8 md/dL when LDL-C 130 mg/dL, 88.3-112.4 mg/dL when non-HDL-C 160 mg/dL, and 67.8-147.4 md/dL when triglycerides 115 mg/dL. At these levels (±10 mg/dL), 10-year ASCVD rates for apoB above mean + 1 SD vs. below mean - 1 SD were 7.3 vs. 4.0 for LDL-C, 6.4 vs. 4.6 for non-HDL-C, and 7.0 vs. 4.6 for triglycerides (all P < .001). With 19 982 new-onset ASCVD events on follow-up, in the adjusted model, residual apoB remained statistically significant after accounting for LDL-C and HDL-C (hazard ratio 1.06, 95% confidence interval 1.0-1.07), after accounting for non-HDL-C and HDL-C (hazard ratio 1.04, 95% confidence interval 1.03-1.06), and after accounting for triglycerides and HDL-C (hazard ratio 1.13, 95% confidence interval 1.12-1.15). None of the residuals of LDL-C, non-HDL-C, or of log triglycerides remained significant when apoB was included in the model. CONCLUSIONS: High variability of apoB at individual levels of LDL-C, non-HDL-C, and triglycerides coupled with meaningful differences in 10-year ASCVD rates and significant residual information contained in apoB for prediction of new-onset ASCVD events demonstrate that LDL-C, non-HDL-C, and triglycerides are not adequate proxies for apoB in clinical care.

Tobacco use and risk of acute stroke in 32 countries in the INTERSTROKE study: a case­control study

BACKGROUND Smoking is a major risk factor for the global burden of stroke. We have previously reported a global population attributable risk (PAR) of stroke of 12.4% associated with current smoking. In this study we aimed to explore the association of current tobacco use with different types of tobacco exposure and environmental tobacco smoke (ETS) exposure on the risk of stroke and stroke subtypes, and by regions and country income levels. METHODS The INTERSTROKE study is a case­control study of acute first stroke and was undertaken with 13,462 stroke cases and 13,488 controls recruited between January 11, 2007 and August 8, 2015 in 32 countries worldwide. Association of risk of tobacco use and ETS exposure were analysed with overall stroke, ischemic and intracerebral hemorrhage (ICH), and with TOAST etiological stroke subtypes (large vessel, small vessel, cardioembolism, and undetermined). FINDINGS Current smoking was associated with an increased risk of all stroke (odds ratio [OR] 1.64, 95% CI 1.46­1.84), and had a stronger association with ischemic stroke (OR 1.85, 95% CI 1.61­2.11) than ICH (OR 1.19 95% CI 1.00­1.41). The OR and PAR of stroke among current smokers varied significantly between regions and income levels with high income countries (HIC) having the highest odds (OR 3.02 95% CI 2.24­4.10) and PAR (18.6%, 15.1­22.8%). Among etiological subtypes of ischemic stroke, the strongest association of current smoking was seen for large vessel stroke (OR 2.16, 95% CI 1.63­2.87) and undetermined cause (OR 1.97, 95% CI 1.55­2.50). Both filtered (OR 1.73, 95% CI 1.50­1.99) and non-filtered (OR 2.59, 95% CI 1.79­3.77) cigarettes were associated with stroke risk. ETS exposure increased the risk of stroke in a dose-dependent manner, exposure for more than 10 h per week increased risk for all stroke (OR 1.95, 95% CI 1.69­2.27), ischemic stroke (OR 1.89, 95% CI 1.59­2.24) and ICH (OR 2.00, 95% CI 1.60­2.50). INTERPRETATION There are significant variations in the magnitude of risk and PAR of stroke according to the types of tobacco used, active and ETS exposure, and countries with different income levels. Specific strategies to discourage tobacco use by any form and to build a smoke free environment should be implemented to ease the global burden of stroke. FUNDING The Canadian Institutes of Health Research, Heart and Stroke Foundation of Canada, Canadian Stroke Network, Swedish Research Council, Swedish Heart and Lung Foundation, The Health & Medical Care Committee of the Regional Executive Board, Region Västra Götaland, and through unrestricted grants from several pharmaceutical companies with major contributions from Astra Zeneca, Boehringer Ingelheim (Canada), Pfizer (Canada), MERCK, Sharp and Dohme, Swedish Heart and Lung Foundation, UK Chest, and UK Heart and Stroke.

Tobacco use and risk of acute stroke in 32 countries in the INTERSTROKE study: a case-control study.

Background: Smoking is a major risk factor for the global burden of stroke. We have previously reported a global population attributable risk (PAR) of stroke of 12.4% associated with current smoking. In this study we aimed to explore the association of current tobacco use with different types of tobacco exposure and environmental tobacco smoke (ETS) exposure on the risk of stroke and stroke subtypes, and by regions and country income levels. Methods: The INTERSTROKE study is a case-control study of acute first stroke and was undertaken with 13,462 stroke cases and 13,488 controls recruited between January 11, 2007 and August 8, 2015 in 32 countries worldwide. Association of risk of tobacco use and ETS exposure were analysed with overall stroke, ischemic and intracerebral hemorrhage (ICH), and with TOAST etiological stroke subtypes (large vessel, small vessel, cardioembolism, and undetermined). Findings: Current smoking was associated with an increased risk of all stroke (odds ratio [OR] 1.64, 95% CI 1.46-1.84), and had a stronger association with ischemic stroke (OR 1.85, 95% CI 1.61-2.11) than ICH (OR 1.19 95% CI 1.00-1.41). The OR and PAR of stroke among current smokers varied significantly between regions and income levels with high income countries (HIC) having the highest odds (OR 3.02 95% CI 2.24-4.10) and PAR (18.6%, 15.1-22.8%). Among etiological subtypes of ischemic stroke, the strongest association of current smoking was seen for large vessel stroke (OR 2.16, 95% CI 1.63-2.87) and undetermined cause (OR 1.97, 95% CI 1.55-2.50). Both filtered (OR 1.73, 95% CI 1.50-1.99) and non-filtered (OR 2.59, 95% CI 1.79-3.77) cigarettes were associated with stroke risk. ETS exposure increased the risk of stroke in a dose-dependent manner, exposure for more than 10 h per week increased risk for all stroke (OR 1.95, 95% CI 1.69-2.27), ischemic stroke (OR 1.89, 95% CI 1.59-2.24) and ICH (OR 2.00, 95% CI 1.60-2.50). Interpretation: There are significant variations in the magnitude of risk and PAR of stroke according to the types of tobacco used, active and ETS exposure, and countries with different income levels. Specific strategies to discourage tobacco use by any form and to build a smoke free environment should be implemented to ease the global burden of stroke. Funding: The Canadian Institutes of Health Research, Heart and Stroke Foundation of Canada, Canadian Stroke Network, Swedish Research Council, Swedish Heart and Lung Foundation, The Health & Medical Care Committee of the Regional Executive Board, Region Västra Götaland, and through unrestricted grants from several pharmaceutical companies with major contributions from Astra Zeneca, Boehringer Ingelheim (Canada), Pfizer (Canada), MERCK, Sharp and Dohme, Swedish Heart and Lung Foundation, UK Chest, and UK Heart and Stroke.

Low-density lipoprotein cholesterol, non-high-density lipoprotein cholesterol and apolipoprotein B for cardiovascular care.

PURPOSE OF REVIEW: Some experts and consensus groups continue to argue that apolipoprotein B (apoB) should not be introduced broadly into clinical care. But, too often, the present approach to clinical care is not succeeding. An important reason for this failure, we believe, is that the conventional approach limits what the expert clinician can accomplish and is too complex, confusing, and contradictory for primary care physicians to apply effectively in their practise. RECENT FINDINGS: There are four major reasons that apoB should be measured routinely in clinical care. First, apoB is a more accurate marker of cardiovascular risk than LDL-C or non-HDL-C. Second, the measurement of apoB is standardized whereas the measurements of LDL-C and non-HDL-C are not. Third, with apoB and a conventional lipid panel, all the lipid phenotypes can be simply and accurately distinguished. This will improve the care of the expert. Fourth, apoB, as the single measure to evaluate the success of therapy, would simplify the process of care for primary care physicians. SUMMARY: By introducing apoB broadly into clinical care, the process of care will be improved for both the expert and the primary care physician, and this will improve the outcomes of care.

Triglyceride-rich lipoprotein cholesterol and cardiovascular risk.

PURPOSE OF REVIEW: The triglyceride-rich apoB lipoprotein particles make up a minority of the apoB particles in plasma. They vary in size, in lipid, and in protein content. Most are small enough to enter the arterial wall and therefore most are atherogenic. But how important a contribution TRL particles make to the total risk created by the apoB lipoproteins remains controversial. A recent Mendelian randomization analysis determined that the cardiovascular risk related to the cholesterol within these apoB particles--the TRL cholesterol--was greater than--and independent of--the risk related to apoB. If correct, these observations have major clinical significance. RECENT FINDINGS: Accordingly, we have analyzed these results in detail. In our view, the independent strength of the association between TRL cholesterol and apoB with cardiovascular risk seems inconsistent with the biological connections between apoB and cholesterol as integral and highly correlated constituents of apoB particles. These results are also inconsistent with other lines of evidence such as the results of the fibrate randomized clinical trials. Moreover, we are also concerned with other aspects of the analysis. SUMMARY: We do not regard the issue as settled. However, this enquiry has led us to a fuller understanding of the determinants of the cholesterol content of the TRL apoB particles and the complex processing of cholesterol amongst the plasma lipoproteins.

Concordance/discordance between serum apolipoprotein B, low density lipoprotein cholesterol and non-high density lipoprotein cholesterol in NATPOL 2011 participants - An epidemiological perspective.

BACKGROUND: The study compared the distribution of serum LDL-C, non-HDL-C, and apolipoprotein B (apoB) among participants of the NATPOL 2011 survey and analysed concordance/discordance of results in the context of the risk for atherosclerotic cardiovascular disease (ASCVD). METHODS: Serum levels of apoB, LDL-C, non-HDL-C and small dense LDL-C were measured/calculated in 2067-2098 survey participants. The results were compared between women and men, age groups and in relation to body mass index (BMI), fasting glucose and TG levels, and the presence of CVD. Percentile distribution of lipid levels and concordance/discordance analysis were based on medians and ESC/EAS 2019 target thresholds for ASCVD risk and on comparison of measured apoB levels and levels calculated from linear regression equations with serum LDL- C and non-HDL-C as independent variables. RESULTS: Serum apoB, LDL-C and non-HDL-C were similarly related to sex, age, BMI, visceral obesity, cardiovascular disease, and fasting glucose and triglyceride levels. Serum apoB, LDL-C and non-HDL-C very high- and moderate- target thresholds were exceeded in 83%, 99% and 96.9% and in 41%, 75% and 63.7% of subjects, respectively. The incidence of the discordances between the results depended on the dividing values used and ranged from 0.2% to 45.2% of the respondents. Subjects with high apoB / low LDL-C/non-HDL-C discordance had features of metabolic syndrome. CONCLUSIONS: Diagnostic discordances between apoB and LDL-C/non-HDL-C indicate limitations of serum LDL-C/non-HDL-C in ASCVD risk management. Due to the high apoB/low LDL-C/non-HDL-C discordance, obese/metabolic syndrome patients may benefit from replacing LDL-C/non-HDL-C by apoB in ASCVD risk assessment and lipid-lowering therapy.

Standardization of Apolipoprotein B, LDL-Cholesterol, and Non-HDL-Cholesterol.

Concern continues about whether the measurement of apolipoprotein B (apoB) is adequately standardized, and therefore, whether apoB should be applied widely in clinical care. This concern is misplaced. Our objective is to explain why and what the term "standardization" means. To produce clinically valid results, a test must accurately, precisely, and selectively measure the marker of interest. That is, it must be standardized. Accuracy refers to how closely the result obtained with 1 method corresponds to the result obtained with the standard method, precision to how reproducible the result is on repeated testing, and selectivity to how susceptible the method is to error by inclusion of other classes of lipoprotein particles. Multiple expert groups have determined that the measurement of apoB is adequately standardized for clinical care, and that apoB can be measured inexpensively, using widely available automated methods, more accurately, precisely, and selectively than low-density lipoprotein cholesterol or non-high-density lipoprotein cholesterol. ApoB is a standard superior to low-density lipoprotein cholesterol and high-density lipoprotein cholesterol because it is a defined molecule, whereas the cholesterol markers are the mass of cholesterol within lipoprotein particles defined by their density, not by their molecular structure. Nevertheless, the standardization of apoB is being further improved by the application of mass spectrophotometric methods, whereas the limitations in the standardization and, therefore, the accurate, precise, and selective measurement of low-density lipoprotein cholesterol and high-density lipoprotein cholesterol are unlikely to be overcome. We submit that greater accuracy, precision, and selectivity in measurement is a decisive advantage for apoB in the modern era of intensive lipid-lowering therapies.

Is hypertriglyceridemia a reliable indicator of cholesterol-depleted Apo B particles?

OBJECTIVES: Because cholesterol-depleted Apo B particles are thought to be a hallmark of hypertriglyceridemia, American, Canadian and European Lipid Guidelines suggest screening for Apo B only in patients with hypertriglyceridemia. Accordingly, this study examines the relationship of triglycerides to the LDL-C/Apo B and non-HDL-C/Apo B ratios. METHODS: The study cohort consisted of 6272 NHANES subjects adjusted for a weighted sample size of 150 million subjects without previously diagnosed cardiac disease. Data was reported by LDL-C/Apo B tertiles as weighted frequencies and percent. Sensitivity, specificity, negative predictive and positive predictive values were calculated for triglycerides thresholds of >150 mg/dL and >200 mg/dL. The range of values of Apo B for decisional levels of LDL-C and non-HDL-C were also determined RESULTS: Among patients with triglycerides >200 mg/dL, 75.9% were amongst the lowest LDL-C/Apo B tertile. However, this represents only 7.5% of the total population. Of patients with the lowest LDL-C/Apo B ratio, 59.8% had triglycerides <150 mg/dL. Moreover, there was an inverse relationship between non-HDL-C/Apo B such that elevated triglycerides were associated with the highest tertile of non-HDL-C/Apo B. Finally, the range of values of Apo B for decisional levels of LDL-C and non-HDL-C was determined and is so broad- 30.3-40.6 mg/dl Apo B for different levels of LDL-C and 19.5 to 27.6 mg/dl Apo B for different levels of non-HDL-C- that neither is an adequate clinical surrogate for Apo B. CONCLUSION: Plasma triglycerides should not be used to restrict the measurement of Apo B since cholesterol-depleted Apo B particles may be present at any level of triglyceride.

Preparative Electrophoresis for HDL Particle Size Separation and Intact-Mass Apolipoprotein Proteoform Analysis.

The most abundant proteins on high-density lipoproteins (HDLs), apolipoproteins A-I (APOA1) and A-II (APOA2), are determinants of HDL function with 15 and 9 proteoforms (chemical-structure variants), respectively. The relative abundance of these proteoforms in human serum is associated with HDL cholesterol efflux capacity, and cholesterol content. However, the association between proteoform concentrations and HDL size is unknown. We employed a novel native-gel electrophoresis technique, clear native gel-eluted liquid fraction entrapment electrophoresis (CN-GELFrEE) paired with mass spectrometry of intact proteins to investigate this association. Pooled serum was fractionated using acrylamide gels of lengths 8 and 25 cm. Western blotting determined molecular diameter and intact-mass spectrometry determined proteoform profiles of each fraction. The 8- and 25 cm experiments generated 19 and 36 differently sized HDL fractions, respectively. The proteoform distribution varied across size. Fatty-acylated APOA1 proteoforms were associated with larger HDL sizes (Pearson's R = 0.94, p = 4 × 10-7) and were approximately four times more abundant in particles larger than 9.6 nm than in total serum; HDL-unbound APOA1 was acylation-free and contained the pro-peptide proAPOA1. APOA2 proteoform abundance was similar across HDL sizes. Our results establish CN-GELFrEE as an effective lipid-particle separation technique and suggest that acylated proteoforms of APOA1 are associated with larger HDL particles.

Interplay of Atherogenic Particle Number and Particle Size and the Risk of Coronary Heart Disease.

BACKGROUND: We examined the interplay of apolipoprotein B (apoB) and LDL particle size, approximated by the LDL-cholesterol (LDL-C)/apoB ratio, on the risk of new-onset coronary heart disease (CHD). METHODS: Participants without cardiovascular disease from the UK Biobank (UKB; n = 308 182), the Women's Health Study (WHS; n = 26 204), and the Framingham Heart Study (FHS; n = 2839) were included. Multivariable Cox models were used to assess the relationship between apoB and LDL-C/apoB ratio and incidence of CHD (14 994 events). Our analyses were adjusted for age, sex (except WHS), HDL-cholesterol (HDL-C), systolic blood pressure, antihypertensive treatment, diabetes, and smoking. RESULTS: In all 3 studies, there was a strong positive correlation between apoB and LDL-C (correlation coefficients r = 0.80 or higher) and a weak inverse correlation of apoB with LDL-C/apoB ratio (-0.28 ≤ r ≤ -0.14). For all 3 cohorts, CHD risk was higher for higher levels of apoB. Upon multivariable adjustment, the association between apoB and new-onset CHD remained robust and statistically significant in all 3 cohorts with hazard ratios per 1 SD (95% CI): 1.24 (1.22-1.27), 1.33 (1.20-1.47), and 1.24 (1.09-1.42) for UKB, WHS, and FHS, respectively. However, the association between LDL-C/apoB and CHD was statistically significant only in the FHS cohort: 0.78 (0.64-0.94). CONCLUSIONS: Our analysis confirms that apoB is a strong risk factor for CHD. However, given the null association in 2 of the 3 studies, we cannot confirm that cholesterol-depleted LDL particles are substantially more atherogenic than cholesterol-replete particles. These results lend further support to routine measurement of apoB in clinical care.