Cardiovascular risk assessment incorporates measurement of atherogenic lipids such as non-HDL cholesterol (non-HDL-C). It remains uncertain under which circumstances atherogenic lipoprotein enumeration such as LDL particle number (LDL-P) differs from simultaneously acquired non-HDL-C.
Participants of the Multi-Ethnic Study of Atherosclerosis (MESA) were deemed LDL-P>non-HDL-C discordant if they exhibited higher LDL-P than expected for simultaneously measured non-HDL-C, given the observed distribution of both in MESA. Conversely, a lower LDL-P than would be suggested from non-HDL-C characterized LDL-P
Discordance was observed among 44% of subjects. LDL-P>non-HDL-C compared to LDL-P
Our results demonstrated that disagreement between LDL-P and non-HDL-C was common and significantly associated with several clinical characteristics. In the setting of discordance, LDL-P was more closely associated with CIMT and CAC than non-HDL-C, though observed differences were small.
cholesterol; lipoproteins; risk assessment; LDL-particle number; apolipoprotein B
We evaluated 25 repolarization‐related ECG variables for the risk of coronary heart disease (CHD) death in 52 994 postmenopausal women from the Women's Health Initiative study.
Methods and Results
Hazard ratios from Cox regression were computed for subgroups of women with and without cardiovascular disease (CVD). During the average follow‐up of 16.9 years, 941 CHD deaths occurred. Based on electrophysiological considerations, 2 sets of ECG variables with low correlations were considered as candidates for independent predictors of CHD death: Set 1, Ѳ(Tp|Tref), the spatial angle between T peak (Tp) and normal T reference (Tref) vectors; Ѳ(Tinit|Tterm), the angle between the initial and terminal T vectors; STJ depression in V6 and rate‐adjusted QTp interval (QTpa); and Set 2, TaVR and TV1 amplitudes, heart rate, and QRS duration. Strong independent predictors with over 2‐fold increased risk for CHD death in women with and without CVD were Ѳ(Tp|Tref) >42° from Set 1 and TaVR amplitude >−100 μV from Set 2. The risk for these CHD death predictors remained significant after multivariable adjustment for demographic/clinical factors. Other significant predictors for CHD death in fully adjusted risk models were Ѳ(Tinit|Tterm) >30°, TV1 >175 μV, and QRS duration >100 ms.
Ѳ(Tp|Tref) angle and TaVR amplitude are associated with CHD mortality in postmenopausal women. The use of these measures to identify high‐risk women for further diagnostic evaluation or more intense preventive intervention warrants further study.
Clinical Trial Registration
URL: http://www.clinicaltrials.gov. Unique identifier: NCT00000611.
coronary heart disease; electrocardiography; mortality; repolarization; risk factors
The association between high‐density lipoprotein cholesterol (HDL‐C) and coronary heart disease (CHD) events is not well described in individuals with very high levels of HDL‐C (>80 mg/dL).
Methods and Results
Using pooled data from 6 community‐based cohorts we examined CHD and total mortality risks across a broad range of HDL‐C, including values in excess of 80 mg/dL. We used Cox proportional hazards models with penalized splines to assess multivariable, adjusted, sex‐stratified associations of HDL‐C with the hazard for CHD events and total mortality, using HDL‐C 45 mg/dL and 55 mg/dL as the referent in men and women, respectively. Analyses included 11 515 men and 12 925 women yielding 307 245 person‐years of follow‐up. In men, the association between HDL‐C and CHD events was inverse and linear across most HDL‐C values; however at HDL‐C values >90 mg/dL there was a plateau effect in the pattern of association. In women, the association between HDL‐C and CHD events was inverse and linear across lower values of HDL‐C, however at HDL‐C values >75 mg/dL there were no further reductions in the hazard ratio point estimates for CHD. In unadjusted models there were increased total mortality risks in men with very high HDL‐C, however mortality risks observed in participants with very high HDL‐C were attenuated after adjustment for traditional risk factors.
We did not observe further reductions in CHD risk with HDL‐C values higher than 90 mg/dL in men and 75 mg/dL in women.
CHD events; total mortality; very‐high HDL‐C
Given the results of the JUPITER trial, statin initiation may be considered for individuals with elevated high sensitivity C-reactive protein (CRP). However, if followed prospectively, many individuals with elevated CRP may become statin-eligible, limiting the impact of elevated CRP as a treatment indication. This analysis estimates the proportion of people with elevated CRP that become statin eligible over time.
We followed 2,153 Multi-Ethnic Study of Atherosclerosis (MESA) participants free of cardiovascular disease (CVD) and diabetes with LDL-cholesterol (LDL-C) <130 mg/dL at baseline to determine the proportion who become eligible for statins over 4.5 years. The proportion eligible for statin therapy, defined by the National Cholesterol Education Program (NCEP) 2004 updated guidelines, was calculated at baseline and during follow-up stratified by baseline CRP level (≥2 mg/L).
At baseline, 47% of the 2,153 participants had elevated CRP. Among participants with elevated CRP, 29% met NCEP criteria for statins, compared to 28% without elevated CRP at baseline. By 1.5 years later, 26% and 22% (p=0.09) of those with and without elevated CRP at baseline reached NCEP LDL-C criteria and/or had started statins, respectively. These increased to 42% and 39% (p=0.24) at 3 years and 59% and 52% (p=0.01) at 4.5 years following baseline.
A substantial proportion of those with elevated CRP did not achieve NCEP based statin eligibility over 4.5 years of follow-up. These findings suggest that many patients with elevated CRP may not receive the benefits of statins if CRP is not incorporated into the NCEP screening strategy.
Attention control conditions are used to balance nonspecific attention in randomized trials of behavioral interventions. Very little guidance is available in the literature about which behavioral interventions and outcomes merit an attention control. The primary aim of the present paper is to demonstrate a scenario in which use of attention control in a behavioral randomized trial was unnecessary and possibly detrimental.
Exploratory analyses were performed in a randomized controlled trial that tested whether a patient-centered telephone counseling (PC) intervention reduced low-density lipoprotein cholesterol (LDL-C) levels in 355 participants with peripheral arterial disease (PAD), compared to attention control (AC) and usual care (UC) conditions. The PC intervention was designed to activate participants to ask their physician for lipid-lowering medication and/or increase dose intensity, increase medication adherence, and reduce fat intake. The AC condition involved attention-matched phone-delivered health education, and the UC condition consisted of an educational pamphlet.
At 12-month follow-up, mean LDL-C changes were −11.1, and −6.8 mg/dl in the UC and AC conditions, respectively (p=.17). The proportion of participants who increased use or dose intensity of medication was significantly lower in AC than UC, 17.5% versus 30.5% (p=0.03). No significant difference between AC and UC were observed on other outcomes.
The AC had significantly worse medication outcomes and there was no indication of a therapeutic effect on other endpoints. Implications for use of attention control in behavioral randomized trials are discussed.
Attention control; control groups; placebo; behavioral interventions; randomized controlled trials
An increased risk of breast cancer has been reported in patients with non-melanomatous skin cancer (NMSC), but this association has not been studied in a large, multi-geographic population. We utilized data from the Women's Health Initiative observational study to assess whether history of NMSC is associated with breast cancer risk. This analysis included 70,246 postmenopausal White and Hispanic women aged 50–79, in which 4,247 breast cancer cases were identified over a mean (SD) of 11.3 (3.2) years. Baseline information was collected on demographics, medical history, sun exposure, and vitamin D intake. Cox proportional hazards regression was used to calculate hazard ratios (HRs) with 95 % confidence intervals (CIs). The relationship between NMSC and breast cancer was examined as a time-dependent exposure using updated information on NMSC gathered during follow-up visits. All statistical tests were two sided. There were 5,595 women diagnosed with NMSC at study entry. The annualized rate of breast cancer was 0.64 % among women with a history of NMSC and 0.55 % among women with no history of NMSC. The multivariable-adjusted HR for breast cancer among women with a history of NMSC versus no history of NMSC was 1.07 (95 % CI 0.95–1.20, P = 0.27). Further evaluation stratified by tumor characteristics showed an increased risk of lymph node-positive disease, HR = 1.30 (95 % CI 1.01–1.67, P = 0.04), and regional-stage disease, HR = 1.33 (95 % CI 1.05–1.70, P = 0.02), among women with NMSC. There was no significant overall association between NMSC and breast cancer; however, there was an increased risk of more advanced-stage breast cancer which needs further exploration.
Non-melanomatous skin cancer; Breast cancer; Women's Health Initiative; Cohort study; Cancer risk
The discrimination of a risk prediction model measures that model's ability to distinguish between subjects with and without events. The area under the receiver operating characteristic curve (AUC) is a popular measure of discrimination. However, the AUC has recently been criticized for its insensitivity in model comparisons in which the baseline model has performed well. Thus, 2 other measures have been proposed to capture improvement in discrimination for nested models: the integrated discrimination improvement and the continuous net reclassification improvement. In the present study, the authors use mathematical relations and numerical simulations to quantify the improvement in discrimination offered by candidate markers of different strengths as measured by their effect sizes. They demonstrate that the increase in the AUC depends on the strength of the baseline model, which is true to a lesser degree for the integrated discrimination improvement. On the other hand, the continuous net reclassification improvement depends only on the effect size of the candidate variable and its correlation with other predictors. These measures are illustrated using the Framingham model for incident atrial fibrillation. The authors conclude that the increase in the AUC, integrated discrimination improvement, and net reclassification improvement offer complementary information and thus recommend reporting all 3 alongside measures characterizing the performance of the final model.
area under curve; biomarkers; discrimination; risk assessment; risk factors
The purpose of this study was to assess the prevalence and distribution of coronary artery calcium (CAC) across Framingham Risk Score (FRS) strata and therefore determine FRS levels at which asymptomatic, young to early middle-age individuals could potentially benefit from CAC screening.
High CAC burden is associated with increased risk of coronary events beyond the FRS. Expert panel recommendations for CAC screening are based on data obtained in middle-age and older individuals.
We included 2,831 CARDIA (Coronary Artery Risk Development in Young Adults) study participants with an age range of 33 to 45 years. The number needed to screen ([NNS] number of people in each FRS stratum who need to be screened to detect 1 person with a CAC score above the specified cut point) was used to assess the yield of screening for CAC. CAC prevalence was compared across FRS strata using a chi-square test.
CAC scores >0 and ≥100 were present in 9.9% and 1.8% of participants, respectively. CAC prevalence and amount increased across higher FRS strata. A CAC score >0 was observed in 7.3%, 20.2%, 19.1%, and 44.8% of individuals with FRSs of 0 to 2.5%, 2.6% to 5%, 5.1% to 10%, and >10%, respectively (NNS = 14, 5, 5, and 2, respectively). A CAC score of ≥100 was observed in 1.3%, 2.4%, and 3.5% of those with FRSs of 0 to 2.5%, 2.6% to 5%, and 5.1% to 10%, respectively (NNS = 79, 41, and 29, respectively), but in 17.2% of those with an FRS >10% (NNS = 6). Similar trends were observed when findings were stratified by sex and race.
In this young to early middle-age cohort, we observed concordance between CAC prevalence/amount and FRS strata. Within this group, the yield of screening and possibility of identifying those with a high CAC burden (CAC score of ≥100) is low in those with an FRS of ≤10%, but considerable in those with an FRS >10%.
coronary artery calcium; coronary heart disease; Framingham Risk Score; number needed to screen; risk factors
Return of individual genetic results to research participants, including participants in archives and biorepositories, is receiving increased attention. However, few groups have deliberated on specific results or weighed deliberations against relevant local contextual factors.
The Electronic Medical Records and GEnomics (eMERGE) network, which includes five biorepositories conducting genome-wide association studies, convened a Return of Results Oversight Committee (RROC) to identify potentially returnable results. Network-wide deliberations were then brought to local constituencies for final decision-making.
Defining results that should be considered for return required input from clinicians with relevant expertise and much deliberation. The RROC identified two sex chromosomal anomalies, Klinefelter Syndrome and Turner Syndrome, as well as homozygosity for Factor V Leiden, as findings that could warrant reporting. Views about returning HFE gene mutations associated with hemochromatosis were mixed due to low penetrance. Review of EMRs suggested that most participants with detected abnormalities were unaware of these findings. Local considerations relevant to return varied and, to date, four sites have elected not to return findings (return was not possible at one site).
The eMERGE experience reveals the complexity of return of results decision-making and provides a potential deliberative model for adoption in other collaborative contexts.
Result return; biorepository; electronic medical records; deliberation; context
We sought to determine whether novel markers not involving ionizing radiation could predict CAC progression in a low-risk population.
Increase in coronary artery calcium (CAC) scores over time (CAC progression) improves prediction of coronary heart disease (CHD) events. Due to radiation exposure, CAC measurement represents an undesirable method for repeated risk assessment, particularly in low predicted risk individuals (Framingham Risk Score [FRS] <10%).
From 6814 MESA participants, 2620 individuals were classified as low risk for CHD events (FRS <10%), and had follow-up CAC measurement. In addition to traditional risk factors [(RFs) - base model], various combinations of novel-marker models were selected based on data-driven, clinical, or backward stepwise selection techniques.
Mean follow-up was 2.5 years. CAC progression occurred in 574 participants (22% overall; 214 of 1830 with baseline CAC =0, and 360 of 790 with baseline CAC >0). Addition of various combinations of novel markers to the base model (c-statistic =0.711), showed improvements in discrimination of approximately only 0.005 each (c-statistics 0.7158, 0.7160 and 0.7164) for the best-fit models. All 3 best-fit novel-marker models calibrated well but were similar to the base model in predicting individual risk probabilities for CAC progression. The highest prevalence of CAC progression occurred in the highest compared to the lowest probability quartile groups (39.2–40.3% versus 6.4–7.1%).
In individuals at low predicted risk by FRS, traditional RFs predicted CAC progression in the short term with good discrimination and calibration. Prediction improved minimally when various novel markers were added to the model.
coronary calcium; Framingham risk score; risk factors; progression
Genome wide association studies identified several single nucleotide polymorphisms (SNPs) associated with prevalent coronary heart disease (CHD) but less is known of associations with incident CHD. The association of thirteen published CHD SNPs was examined in five ancestry groups of four large US prospective cohorts.
Methods and Results
The analyses included incident coronary events over 9.1 to 15.7 average follow-up times in up to 26,617 white individuals (6,626 events), 8,018 African Americans (914 events), 1,903 Hispanics (113 events), 3,669 American Indians (595 events) and 885 Asian/Pacific Islanders (66 events). We used Cox proportional hazards models (with additive mode of inheritance) adjusted for age, sex and ancestry (as needed). Nine loci were statistically associated with incident CHD events in whites: 9p21 (rs10757278, p=4.7 × 10−41), 16q23.1 (rs2549513, p=0.0004), 6p24.1 (rs499818, p=0.0002), 2q36.3 (rs2943634, p=6.7 × 10−6), MTHFDIL (rs6922269, p=5.1 × 10−10), APOE (rs429358, p=2.7 × 10−18), ZNF627 (rs4804611, p=5.0 × 10−8), CXCL12 (rs501120, p=1.4 × 10−6) and LPL (rs268, p=2.7 × 10−17). The 9p21 region showed significant between-study heterogeneity, with larger effects in individuals aged 55 years or younger and in women. Inclusion of coronary revascularization procedures among the incident CHD events introduced heterogeneity. The SNPs were not associated with CHD in African Americans and associations varied in other US minorities.
Prospective analyses of white individuals replicated several reported cross-sectional CHD-SNP associations.
9p21 locus; incident coronary heart disease; genetic polymorphisms
Functional biomarkers like large artery elasticity (LAE) and small artery elasticity (SAE) may predict cardiovascular disease (CVD) events beyond blood pressure. The authors examined the prognostic value of LAE and SAE for clinical CVD events among 6,235 Multi-Ethnic Study of Atherosclerosis participants who were initially aged 45–84 years and without symptomatic CVD. LAE and SAE were derived from diastolic pulse contour analysis. During a median 5.8 years of follow-up between 2000 and 2008, 454 adjudicated CVD events occurred, including 256 cases of coronary heart disease (CHD), 93 strokes, and 126 heart failures (multiple diagnoses were possible). After adjustment for age, race/ethnicity, sex, clinic, height, heart rate, body mass index, systolic and diastolic blood pressure, use of antihypertensive and cholesterol-lowering medications, smoking, total cholesterol, high density lipoprotein cholesterol, triglycerides, diabetes, and high-sensitivity C-reactive protein, the hazard ratio for any CVD per standard-deviation increase in SAE was 0.71 (95% confidence interval: 0.61, 0.83; P < 0.0001). The lowest (stiffest) SAE quartile had a hazard ratio of 2.28 (95% confidence interval: 1.55, 3.36) versus the highest (most elastic) quartile. The net reclassification index, conditional on base risk, was 0.11. SAE was significantly associated with future CHD, stroke, and heart failure. After adjustment, LAE was not significantly related to CVD. In asymptomatic participants free of overt CVD, lower SAE added prognostic information for CVD, CHD, stroke, and heart failure events.
arteries; cardiovascular diseases; elasticity; risk factors
To evaluate independent associations of high density lipoprotein cholesterol (HDL-C) and particle (HDL-P) concentrations with carotid intima-media thickness (cIMT) and incident coronary heart disease (CHD).
HDL-C is inversely related to CHD, but also to triglycerides, LDL particles (LDL-P), and related metabolic risk. HDL-P associations with CHD may be partially independent of these factors.
In a multi-ethnic study of 5598 men and women ages 45-84, without baseline CHD, excluding subjects on lipid-lowering medications, triglycerides >400 mg/dl or missing values, we evaluated associations of HDL-C and NMR-spectroscopy-measured HDL-P with cIMT and incident CHD (myocardial infarction, CHD death, angina, n=227 events, 6.0 years mean follow-up). All models were adjusted for age, sex, ethnicity, hypertension and smoking.
HDL-C and HDL-P correlated with each other (π=0.69) and LDL-P (π = −0.38, −0.25, respectively), p<0.05 for all. For (1-SD) higher HDL-C (15 mg/dl) or HDL-P (6.64 μmol/l), cIMT differences (95%CI) were −26.1(−34.7,−17.4) and −30.1 (−38.8,−21.4) μm, and CHD hazard ratios (HR (95%CI)) were 0.74 (0.63, 0.88) and 0.70 (0.59, 0.82), respectively. Adjusted for each other and LDL-P, HDL-C was no longer associated with cIMT (2.3 (−9.5, 14.2) μm) or CHD (0.97(0.77, 1.22)), but HDL-P remained independently associated with cIMT (−22.2(−33.8,−10.6) μm) and CHD (0.75 (0.61, 0.93)). Interactions by sex, ethnicity, diabetes and high-sensitivity C-reactive protein were not significant.
Adjusting for each other and LDL-P substantially attenuated associations of HDL-C, but not HDL-P, with cIMT and CHD. Potential confounding by related lipids or lipoproteins should be carefully considered when evaluating HDL-related risk.
Lipids; lipoproteins; high-density lipoprotein cholesterol; high-density lipoprotein particles; cardiovascular disease
The lifetime risks of cardiovascular disease have not been reported across the age spectrum in black adults and white adults.
We conducted a meta-analysis at the individual level using data from 18 cohort studies involving a total of 257,384 black men and women and white men and women whose risk factors for cardiovascular disease were measured at the ages of 45, 55, 65, and 75 years. Blood pressure, cholesterol level, smoking status, and diabetes status were used to stratify participants according to risk factors into five mutually exclusive categories. The remaining lifetime risks of cardiovascular events were estimated for participants in each category at each age, with death free of cardiovascular disease treated as a competing event.
We observed marked differences in the lifetime risks of cardiovascular disease across risk-factor strata. Among participants who were 55 years of age, those with an optimal risk-factor profile (total cholesterol level, <180 mg per deciliter [4.7 mmol per liter]; blood pressure, <120 mm Hg systolic and 80 mm Hg diastolic; nonsmoking status; and nondiabetic status) had substantially lower risks of death from cardiovascular disease through the age of 80 years than participants with two or more major risk factors (4.7% vs. 29.6% among men, 6.4% vs. 20.5% among women). Those with an optimal risk-factor profile also had lower lifetime risks of fatal coronary heart disease or nonfatal myocardial infarction (3.6% vs. 37.5% among men, <1% vs. 18.3% among women) and fatal or nonfatal stroke (2.3% vs. 8.3% among men, 5.3% vs. 10.7% among women). Similar trends within risk-factor strata were observed among blacks and whites and across diverse birth cohorts.
Differences in risk-factor burden translate into marked differences in the lifetime risk of cardiovascular disease, and these differences are consistent across race and birth cohorts. (Funded by the National Heart, Lung, and Blood Institute.)
Whether fish or the fatty acids they contain are independently associated with risk for incident heart failure (HF) among postmenopausal women is unclear.
Methods and Results
The baseline Women’s Health Initiative Observational Study (WHI-OS) cohort consisted of 93,676 women aged 50–79 of diverse ethnicity and background of which 84,493 were eligible for analyses. Intakes of baked/broiled fish, fried fish and omega-3 fatty acid (eicosapentaenoic acid (EPA) + docosahexaenoic acid (DHA), α-linolenic acid (ALA)), and trans fatty acid (TFA) were determined from the WHI food frequency questionnaire. Baked/broiled fish consumption was divided into 5 frequency categories: <1/mo (referent), 1–3/mo, 1–2/wk, 3–4/wk, ≥5/wk. Fried fish intake was grouped into 3 frequency categories: <1/mo (referent), 2) 1–3/mo, and 3) ≥1/wk. Associations between fish or fatty acid intake and incident HF were determined using Cox models adjusting for HF risk factors and dietary factors. Baked/broiled fish consumption (≥5 servings/wk at baseline) was associated with a hazard ratio (HR) of 0.70 (95% CI: 0.51, 0.95) for incident HF. In contrast, fried fish consumption (≥1 serving/wk at baseline) was associated with a HR of 1.48 (95% CI: 1.19, 1.84) for incident HF. No significant associations were found between EPA+DHA, ALA, or TFA intake and incident HF.
Increased baked/broiled fish intake may lower HF risk, while increased fried fish intake may increase HF risk in postmenopausal women.
heart failure; epidemiology; nutrition; women
Peripheral arterial disease patients are less likely than other high-risk patients to achieve ideal low density lipoprotein cholesterol (LDL-cholesterol) levels. This randomized controlled trial assessed whether a telephone counseling intervention, designed to help peripheral arterial disease patients request more intensive cholesterol lowering therapy from their physician, achieves lower LDL-cholesterol levels than two control conditions.
355 peripheral arterial disease participants with baseline LDL-cholesterol ≥ 70 mg/dl were enrolled. The primary outcome was change in LDL-cholesterol level at twelve-month follow-up. There were three parallel arms: telephone counseling intervention, attention control condition, and usual care. The intervention consisted of patient-centered counseling, delivered every six weeks, encouraging participants to request increases in cholesterol-lowering therapy from their physician. The attention control condition consisted of telephone calls every six weeks providing information only. The usual care condition participated in baseline and follow-up testing.
At 12-month follow-up, participants in the intervention improved their LDL-cholesterol level, compared to those in attention control (−18.4 mg/dl vs. −6.8 mg/dl, p= 0.010) but not compared to those in usual care (−18.4 mg/dl vs. −11.1 mg/dl, p= 0.208). Intervention participants were more likely to start a cholesterol-lowering medication or increase their cholesterol-lowering medication dose than those in the attention control (54% vs. 18%, p=0.001) and usual care (54% vs. 31%, P<0.001) conditions.
Telephone counseling that helped peripheral arterial disease patients request more intensive cholesterol-lowering therapy from their physician achieved greater LDL-cholesterol declines than an attention control arm that provided health information alone.
Intermittent claudication; secondary prevention; peripheral arterial disease
By examining the distribution of CAC across FRS strata in a large, multi-ethnic, community-based sample of men and women, we sought to determine if lower risk persons could potentially benefit from CAC screening.
The 10-year Framingham risk scores (FRS) and coronary artery calcium (CAC) are predictors of coronary heart disease (CHD). CAC ≥300 is associated with the highest risk for CHD even in low risk (FRS <10%) persons; however expert groups have suggested CAC screening only in intermediate risk (FRS 10–20%) groups.
We included 5660 MESA participants. The number needed to screen [number of people that need to be screened to detect one person with CAC above the specified cut-point (NNS)] was used to assess the yield of screening for CAC. CAC prevalence was compared across FRS strata using chi-square tests.
CAC >0, ≥100 and ≥300 were present in 46.4%, 20.6% and 10.1% of participants, respectively. Prevalence and amount of CAC increased with higher FRS. CAC ≥300 was observed in 1.7% and 4.4% of those with FRS 0–2.5% and 2.6–5%, respectively (NNS =59.7 and 22.7). Likewise, CAC ≥300 was observed in 24% and 30% of those with FRS 15.1–20% and >20%, respectively (NNS =4.2 and 3.3). Trends were similar when stratified by age, gender and race/ethnicity.
Our study suggests that in very low risk individuals (FRS ≤5%), the yield of screening and probability of identifying persons with clinically significant levels of CAC is low, but becomes greater in low and intermediate risk persons (FRS 5.1–20%).
Framingham risk score; coronary calcium; coronary heart disease; number needed to screen; risk factors; population; atherosclerosis; low risk
Even among asymptomatic people at low risk (<10%) by Framingham Risk Score (FRS), high coronary artery calcium (CAC) scores signify higher predicted risk of coronary heart disease (CHD) events. We sought to determine non-invasive factors (without radiation exposure) significantly associated with CAC in low-risk, asymptomatic persons. In a cross-sectional analysis, we studied 3046 participants from MESA at low 10-year predicted risk (FRS <10%) for CHD events. Multivariable logistic regression was used to assess the association of novel markers with presence of any CAC (CAC >0) and advanced CAC (CAC ≥ 300). CAC >0 and CAC ≥ 300 were present in 30% and 3.5% of participants, respectively. Factor VIIIc, fibrinogen and sICAM were each associated with CAC presence (P ≤ 0.02); and C-reactive protein, D-dimer and carotid intima-media thickness (CIMT) with advanced CAC (P ≤ 0.03). The base model combining traditional risk factors had excellent discrimination for advanced CAC (C-statistic, 0.808). Addition of the 2 best-fit models combining biomarkers plus/minus CIMT improved the c-statistics to 0.822 and 0.820, respectively. All 3 models calibrated well, but were similar in estimating individual risk probabilities for advanced CAC (prevalence = 9.97%, 10.63% and 10.10% in the highest quartiles of predicted probabilities versus 0.26%, 0.26% and 0.26% in the lowest quartiles, respectively). In conclusion, in low risk individuals, traditional risk factors alone predicted advanced CAC with high discrimination and calibration. Biomarker combinations +/− CIMT were also significantly associated with advanced CAC, but improvement in prediction and estimation of clinical risk were modest compared to traditional risk factors alone.
coronary calcium; biomarkers; novel markers; low-risk; risk factors
The amount of cholesterol per LDL particle is variable and related in part to particle size, with smaller particles carrying less cholesterol. This variability causes concentrations of LDL cholesterol (LDL-C) and LDL particles (LDL-P) to be discordant in many individuals.
LDL-P measured by nuclear magnetic resonance (NMR) spectroscopy, calculated LDL-C, and carotid intima-media thickness (IMT) were assessed at baseline in the Multi-Ethnic Study of Atherosclerosis (MESA), a community-based cohort of 6814 persons free of clinical CVD at entry and followed for CVD events (n=319 during 5.5-year follow-up). Discordance, defined as values of LDL-P and LDL-C differing by ≥ 12 percentile units to give equal-sized concordant and discordant subgroups, was related to CVD events and to carotid IMT in models predicting outcomes for a 1 SD difference in LDL-C or LDL-P, adjusted for age, sex and race.
LDL-C and LDL-P were associated with incident CVD overall: hazard ratios (HR [95% CI]) 1.20 [1.08, 1.34] and 1.32 [1.19, 1.47], respectively, but for those with discordant levels, only LDL-P was associated with incident CVD (HR: 1.45 [1.19, 1.78]) (LDL-C HR: 1.07 [0.88, 1.30])). IMT also tracked with LDL-P rather than LDL-C, i.e., adjusted mean IMT of 958, 932, and 917 μm in the LDL-P > LDL-C discordant, concordant, and LDL-P < LDL-C discordant subgroups, respectively, with the difference persisting after adjustment for LDL-C (p=0.002) but not LDL-P (p=0.60).
For individuals with discordant LDL-C and LDL-P levels, the LDL-attributable atherosclerotic risk is better indicated by LDL-P.
LDL particle number; LDL cholesterol; cardiovascular disease risk; NMR; lipoproteins