Comparison of Recommended Eligibility for Primary Prevention Statin Therapy Based on the US Preventive Services Task Force Recommendations vs the ACC/AHA Guidelines

IMPORTANCE

There are important differences among guideline recommendations for using statin therapy in primary prevention. New recommendations from the US Preventive Services Task Force (USPSTF) emphasize therapy based on the presence of 1 or more cardiovascular disease (CVD) risk factors and a 10-year global CVD risk of 10% or greater.

OBJECTIVE

To determine the difference in eligibility for primary prevention statin treatment among US adults, assuming full application of USPSTF recommendations compared with the American College of Cardiology/American Heart Association (ACC/AHA) guidelines.

DESIGN, SETTING, AND PARTICIPANTS

National Health and Nutrition Examination Survey (NHANES) data (2009-2014) were used to assess statin eligibility under the 2016 USPSTF recommendations vs the 2013 ACC/AHA cholesterol guidelines among a nationally representative sample of 3416 US adults aged 40 to 75 years with fasting lipid data and triglyceride levels of 400 mg/dL or less, without prior CVD.

EXPOSURES

The 2016 USPSTF recommendations vs 2013 ACC/AHA guidelines.

MAIN OUTCOMES AND MEASURES

Eligibility for primary prevention statin therapy.

RESULTS

Among the US primary prevention population represented by 3416 individuals in NHANES, the median weighted age was 53 years (interquartile range, 46-61), and 53% (95% CI, 52%-55%) were women. Along with the 21.5% (95% CI, 19.3%-23.7%) of patients who reported currently taking lipid-lowering medication, full implementation of the USPSTF recommendations would be associated with initiation of statin therapy in an additional 15.8% (95% CI, 14.0%-17.5%) of patients, compared with an additional 24.3% (95% CI, 22.3%-26.3%) of patients who would be recommended for statin initiation under full implementation of the 2013 ACC/AHA guidelines. Among the 8.9% of individuals in the primary prevention population who would be recommended for statins by ACC/AHA guidelines but not by USPSTF recommendations, 55% would be adults aged 40 to 59 years with a mean 30-year cardiovascular risk greater than 30%, and 28% would have diabetes.

CONCLUSIONS AND RELEVANCE

In this sample of US adults from 2009-2014, adherence to the 2016 USPSTF recommendations for statin therapy, compared with the 2013 ACC/AHA guidelines, could lead to a lower number of individuals recommended for primary prevention statin therapy, including many younger adults with high mean long-term CVD risk.

Discordance between Circulating Atherogenic Cholesterol Mass and Lipoprotein Particle Concentration in Relation to Future Coronary Events in Women

BACKGROUND

It is uncertain whether measurement of circulating total atherogenic lipoprotein particle cholesterol mass [non-HDL cholesterol (nonHDLc)] or particle concentration [apolipoprotein B (apo B) and LDL particle concentration (LDLp)] more accurately reflects risk of incident coronary heart disease (CHD). We evaluated CHD risk among women in whom these markers where discordant.

METHODS

Among 27533 initially healthy women in the Women's Health Study (NCT00000479), using residuals from linear regression models, we compared risk among women with higher or lower observed particle concentration relative to nonHDLc (highest and lowest residual quartiles, respectively) to individuals with agreement between markers (middle quartiles) using Cox proportional hazards models.

RESULTS

Although all 3 biomarkers were correlated (r ≥ 0.77), discordance occurred in up to 20.2% of women. Women with discordant high particle concentration were more likely to have metabolic syndrome (MetS) and diabetes (both P < 0.001). Over a median follow-up of 20.4 years, 1246 CHD events occurred (514725 person-years). Women with high particle concentration relative to nonHDLc had increased CHD risk: age-adjusted hazard ratio (95% CI) = 1.77 (1.56-2.00) for apo B and 1.70 (1.50-1.92) for LDLp. After adjustment for clinical risk factors including MetS, these risks attenuated to 1.22 (1.07-1.39) for apo B and 1.13 (0.99-1.29) for LDLp. Discordant low apo B or LDLp relative to nonHDLc was not associated with lower risk.

CONCLUSIONS

Discordance between atherogenic particle cholesterol mass and particle concentration occurs in a sizeable proportion of apparently healthy women and should be suspected clinically among women with cardiometabolic traits. In such women, direct measurement of lipoprotein particle concentration might better inform CHD risk assessment.

Estimating the Population Impact of Lp(a) Lowering on the Incidence of Myocardial Infarction and Aortic Stenosis—Brief Report

Objective—

High lipoprotein(a) (Lp[a]) is the most common genetic dyslipidemia and is a causal factor for myocardial infarction (MI) and aortic stenosis (AS). We sought to estimate the population impact of Lp(a) lowering that could be achieved in primary prevention using the therapies in development.

Approach and Results—

We used published data from 2 prospective cohorts. High Lp(a) was defined as ≥50 mg/dL (≈20th percentile). Relative risk, attributable risk, the attributable risk percentage, population attributable risk, and the population attributable risk percentage were calculated as measures of the population impact. For MI, the event rate was 4.0% versus 2.8% for high versus low Lp(a) (relative risk, 1.46; 95% confidence interval [CI], 1.45–1.46). The attributable risk was 1.26% (95% CI, 1.24–1.27), corresponding to 31.3% (95% CI, 31.0–31.7) of the excess MI risk in those with high Lp(a). The population attributable risk was 0.21%, representing a population attributable risk percentage of 7.13%. For AS, the event rate was 1.51% versus 0.78% for high versus low Lp(a) (relative risk, 1.95; 95% CI, 1.94–1.97). The attributable risk was 0.74% (95% CI, 0.73–0.75), corresponding to 48.8% (95% CI, 48.3–49.3) of the excess AS risk in those with high Lp(a). The population attributable risk was 0.13%, representing a population attributable risk percentage of 13.9%. In sensitivity analyses targeting the top 10% of Lp(a), the population attributable risk percentage was 5.2% for MI and 7.8% for AS.

Conclusions—

Lp(a) lowering among the top 20% of the population distribution for Lp(a) could prevent 1 in 14 cases of MI and 1 in 7 cases of AS, suggesting a major impact on reducing the burden of cardiovascular disease. Targeting the top 10% could prevent 1 in 20 MI cases and 1 in 12 AS cases.

Age and Cardiovascular Risk Attributable to Apolipoprotein B, Low-Density Lipoprotein Cholesterol or Non-High-Density Lipoprotein Cholesterol

BACKGROUND

Higher concentrations of the apolipoprotein B (apoB) lipoproteins increase the risk of cardiovascular disease. However, whether the risk associated with apoB lipoproteins varies with age has not been well examined.

METHODS AND RESULTS

We determined the associations for total cholesterol, low-density lipoprotein (LDL)-cholesterol (LDL-C), non-high-density lipoprotein-cholesterol (non-HDL-C), apoB, apolipoprotein A-I (apoA-I), and HDL-cholesterol (HDL-C) with myocardial infarction at different ages in 11 760 controls and 8998 myocardial infarction cases of the INTERHEART Study. Logistic regression was used to compute the odds ratio of myocardial infarction for 1 SD change in each lipid marker by decade from <40 to >70 years of age. Except for those >70, plasma levels of total cholesterol, LDL-C, and non-HDL-C and apoB were greater in cases than controls. However, the average levels of these markers decreased significantly as age increased. By contrast, levels of apoA-I and HDL-C were significantly greater in controls than cases but increased significantly as age increased. The cardiovascular risk associated with the atherogenic lipid markers differed at different ages. Most notably, there was a significant decline in the odds ratio for total cholesterol, LDL-C, and non-HDL-C, and apoB with increases in age whereas the odds ratios associated with apoA-I and HDL-C were consistent across the age groups.

CONCLUSIONS

These data indicate that the risk of cardiovascular events associated with apoB particles is greater in younger compared to older individuals. This finding is consistent with greater relative benefit from LDL-lowering therapy in younger compared to older individuals and so argues for therapy in younger individuals with elevated lipids.

High Ultrafiltration Rates Increase Troponin Levels in Stable Hemodialysis Patients

BACKGROUND

An elevated troponin level is commonly found in asymptomatic patients on hemodialysis (HD) and is associated with higher risk of mortality and major adverse cardiovascular events. The underlying mechanism for the association between adverse outcomes and elevated troponin levels has not been elucidated.

METHODS

Two hundred thirty-six stable chronic HD patients from 2 tertiary care centers were enrolled in this study. We measured pre-dialysis troponin I levels with routine monthly bloods for 3 consecutive months. Troponin I was considered to be elevated if it exceeded the laboratory reference range of 0.06 μg/l.

RESULTS

The study population had a mean age of 67.5, 56% were male, 47% had diabetes and 28% had pre-existing coronary artery disease. Eighty-eight positive troponin values were recorded (13% of the available values) in 52 patients. In a repeated measures linear random effects model (univariate analysis), high ultrafiltration (UF), high inter-dialytic weight gain, and duration of the dialysis session, but not intra-dialytic hypotension, were associated with troponin I elevation. In the multivariate model, only high UF explained troponin I elevation (p = 0.04). The intraclass correlation coefficient was found to be 5.8%, suggesting that observed variability is within and not between subjects, with session-related parameters being more important than inter-individual differences.

CONCLUSIONS

A high UF rate during HD is associated with a biochemical evidence of myocardial injury. If confirmed, efforts to avoid rapid UF, protect residual kidney function or minimize weight gain between sessions may impact cardiovascular outcomes in this high-risk population.

Individualized Statin Benefit for Determining Statin Eligibility in the Primary Prevention of Cardiovascular Disease

BACKGROUND

Current guidelines recommend statins in the primary prevention of cardiovascular disease on the basis of predicted cardiovascular risk without directly considering the expected benefits of statin therapy based on the available randomized, controlled trial evidence.

METHODS AND RESULTS

We included 2134 participants representing 71.8 million American residents potentially eligible for statins in primary prevention from the National Health and Nutrition Examination Survey for the years 2005 to 2010. We compared statin eligibilities using 2 separate approaches: a 10-year risk-based approach (≥7.5% 10-year risk) and an individualized benefit approach (ie, based on predicted absolute risk reduction over 10 years [ARR10] ≥2.3% from randomized, controlled trial data). A risk-based approach led to the eligibility of 15.0 million (95% confidence interval, 12.7-17.3 million) Americans, whereas a benefit-based approach identified 24.6 million (95% confidence interval, 21.0-28.1 million). The corresponding numbers needed to treat over 10 years were 21 (range, 9-44) and 25 (range, 9-44). The benefit-based approach identified 9.5 million lower-risk (<7.5% 10-year risk) Americans not currently eligible for statin treatment who had the same or greater expected benefit from statins (≥2.3% ARR10) compared with higher-risk individuals. This lower-risk/acceptable-benefit group includes younger individuals (mean age, 55.2 versus 62.5 years; P<0.001 for benefit based versus risk based) with higher low-density lipoprotein cholesterol (140 versus133 mg/dL; P=0.01). Statin treatment in this group would be expected to prevent an additional 266 508 cardiovascular events over 10 years.

CONCLUSIONS

An individualized statin benefit approach can identify lower-risk individuals who have equal or greater expected benefit from statins in primary prevention compared with higher-risk individuals. This approach may help develop guideline recommendations that better identify individuals who meaningfully benefit from statin therapy.

Apolipoprotein B improves risk assessment of future coronary heart disease in the Framingham Heart Study beyond LDL-C and non-HDL-C

AIMS

Analyses using conventional statistical methodologies have yielded conflicting results as to whether low-density lipoprotein cholesterol (LDL-C) or non-high-density lipoprotein cholesterol (non-HDL-C) or apolipoprotein B (apoB) is the best marker of the apoB-associated risk of coronary heart disease. The aim of this study was to determine the additional value of apoB beyond LDL-C or non-HDL-C as a predictor of coronary heart disease.

METHODS AND RESULTS

For each patient from the Framingham Offspring Cohort aged 40-75 years (n = 2966), we calculated the extent to which the observed apoB differed from the expected apoB based on their LDL-C or non-HDL-C. We added this difference to a Cox model predicting new onset coronary heart disease over a maximum of 20 years adjusting for standard risk factors plus LDL-C or non-HDL. The difference between observed and expected apoB over LDL-C or non-HDL-C was highly prognostic of future coronary heart disease events: adjusted hazard ratios 1.26 (95% confidence interval: 1.15, 1.37) and 1.20 (1.11, 1.29), respectively, for each standard deviation increase beyond expected apoB levels. When this difference between observed and expected apoB was added to standard coronary heart disease prediction models including LDL-C or non-HDL-C, prediction improved significantly (likelihood ratio test p-values <0.0001) and discrimination c-statistics increased from 0.72 to 0.73. The corresponding relative integrated discrimination improvements were 11% and 8%, respectively.

CONCLUSIONS

apoB improves risk assessment of future coronary heart disease events over and beyond LDL-C or non-HDL-C, which is consistent with coronary risk being more closely related to the number of atherogenic apoB particles than to the mass of cholesterol within them.

Patient-Level Discordance in Population Percentiles of the Total Cholesterol to High-Density Lipoprotein Cholesterol Ratio in Comparison With Low-Density Lipoprotein Cholesterol and Non-High-Density Lipoprotein Cholesterol: The Very Large Database of Lipids Study (VLDL-2B)

BACKGROUND

The total cholesterol to high-density lipoprotein cholesterol (TC/HDL-C) ratio, estimated low-density lipoprotein cholesterol (LDL-C), and non-HDL-C are routinely available from the standard lipid profile. We aimed to assess the extent of patient-level discordance of TC/HDL-C with LDL-C and non-HDL-C, because discordance suggests the possibility of additional information.

METHODS AND RESULTS

We compared population percentiles of TC/HDL-C, Friedewald-estimated LDL-C, and non-HDL-C in 1 310 432 US adults from the Very Large Database of Lipids. Lipid testing was performed by ultracentrifugation (Vertical Auto Profile, Atherotech, AL). One in 3 patients had ≥25 percentile units discordance between TC/HDL-C and LDL-C, whereas 1 in 4 had ≥25 percentile units discordance between TC/HDL-C and non-HDL-C. The proportion of patients with TC/HDL-C > LDL-C by ≥25 percentile units increased from 3% at triglycerides <100 mg/dL to 51% at triglycerides 200 to 399 mg/dL. On a smaller scale, TC/HDL-C > non-HDL-C discordance by ≥25 percentile units increased from 6% to 21%. In those with <15th percentile levels of LDL-C (<70 mg/dL) or non-HDL-C (<93 mg/dL), a respective 58% and 46% were above the percentile-equivalent TC/HDL-C of 2.6. Age, sex, and directly measured components of the standard lipid profile explained >86% of the variance in percentile discordance between TC/HDL-C versus LDL-C and non-HDL-C.

CONCLUSIONS

In this contemporary, cross-sectional, big data analysis of US adults who underwent advanced lipid testing, the extent of patient-level discordance suggests that TC/HDL-C may offer potential additional information to LDL-C and non-HDL-C. Future studies are required to determine the clinical implications of this observation.

CLINICAL TRIAL REGISTRATION

URL: http://www.clinicaltrials.gov. Unique identifier: NCT01698489.

Lipid phenotypes at the extremes of high-density lipoprotein cholesterol: The very large database of lipids-9

BACKGROUND

Low serum levels of high-density lipoprotein cholesterol (HDL-C) are an important risk factor for atherosclerotic disease. To date, therapeutically raising HDL-C has not been shown to impact risk for cardiovascular events.

OBJECTIVE

We aim to characterize lipid parameters at the extremes of HDL-C.

METHODS

We examined cholesterol profiles from 1,350,908 US adults and children from the Very Large Database of Lipids who were clinically referred for advanced lipoprotein testing from 2009 to 2011. We categorized patients into HDL-C percentile categories (<0.1th, 0.1th-<1st, 1st-5th, 25th-75th, 95th-99th, >99th-99.9th, and >99.9th). Within these groups, we examined HDL-C subclasses, low-density lipoprotein cholesterol (LDL-C), LDL and very-low density lipoprotein densities, non-HDL-C, triglycerides (TG), very-low density lipoprotein cholesterol, and remnant lipoprotein cholesterol (RLP-C), as well as prevalence of Fredrickson-Levy dyslipidemias.

RESULTS

Extremely low HDL-C percentiles were associated with increased LDL density, TG, and especially RLP-C. Very high HDL-C levels (≥ 92 mg/dL) showed increasing HDL2-C/HDL3-C ratio and very low levels of RLP-C and triglyceride-rich lipoproteins. Type IV dyslipidemia had the highest prevalence among classical dyslipidemia and was the most frequent at extremely low HDL-C percentiles.

CONCLUSIONS

These findings demonstrate a high prevalence of elevated triglyceride-rich lipoprotein levels and increased LDL density in patients with extremely low HDL-C levels. The relative contributions of these various changes in lipid profiles of patients with low HDL-C to cardiovascular risk need to be further scrutinized to more fully establish if low HDL-C is truly an independent risk factor for coronary heart disease or simply reflects detrimental shifts in the levels of atherogenic lipoproteins.

Limitations in the conventional assessment of the incremental value of predictors of cardiovascular risk

PURPOSE OF REVIEW

Whether a factor significantly increases the area under the curve (AUC) of a receiver operating characteristic analysis has become the standard test of its utility. Thus, in many studies, apolipoprotein B and LDL particle number have not increased the AUC significantly beyond that produced by the conventional markers, and guideline groups have concluded on this basis that they should not be added to routine clinical practice. This article demonstrates this conclusion to be invalid.

RECENT FINDINGS

In conventional analyses, no distinctions have been drawn as to whether a novel predictor is causal or whether it is highly correlated with other markers already included in the risk algorithm. However, correlation among the markers will profoundly affect the incremental effect of a factor on the AUC. This distinction is particularly critical for factors that have been shown to play a causal role in the production of clinical event. Accordingly, the AUC approach is valid to determine the total discriminatory ability of a set of variables but is not appropriate to allocate attributable risk among the members of the set.

SUMMARY

For correlated predictors that describe different aspects of the same variable such as non-HDL-C and apoB or LDL-C and LDL particle number, discordance analysis offers a simple valid alternative to capture and compare the independent information contained by each predictor.

Using age- and sex-specific risk thresholds to guide statin therapy: one size may not fit all

BACKGROUND

New cholesterol guidelines emphasize 10-year risk of cardiovascular disease (CVD) to identify adults eligible for statin therapy as primary prevention. Whether these CVD risk thresholds should be individualized by age and sex has not been explored.

OBJECTIVES

This study evaluated the potential impact of incorporating age- and sex-specific CVD risk thresholds into current cholesterol guidelines.

METHODS

Using data from the Framingham Offspring Study, this study assessed current treatment recommendations among age- and sex-specific groups in 3,685 participants free of CVD. Then, it evaluated how varying age- and sex-specific 10-year CVD risk thresholds for statin treatment affect the sensitivity and specificity for incident 10-year CVD events.

RESULTS

Basing statin therapy recommendations on a 10-year fixed risk threshold of 7.5% results in lower statin consideration among women than men (63% vs. 33%; p<0.0001), yet most of the study participants who were 66 to 75 years of age were recommended for statin treatment (90.3%). The fixed 7.5% threshold had relatively low sensitivity for capturing 10-year events in younger women and men (40 to 55 years of age). Sensitivity of the recommendations was substantially improved when the treatment threshold was reduced to 5% in participants who were 40 to 55 years of age. Among older adults (66 to 75 years of age), specificity was poor, but when the treatment threshold was raised to 10% in women and 15% in men, specificity significantly improved, with minimal loss in sensitivity.

CONCLUSIONS

Cholesterol treatment recommendations could be improved by using individualized age- and sex-specific CVD risk thresholds.

Hyperlipidemia in early adulthood increases long-term risk of coronary heart disease

BACKGROUND

Many young adults with moderate hyperlipidemia do not meet statin treatment criteria under the new American Heart Association/American College of Cardiology cholesterol guidelines because they focus on 10-year cardiovascular risk. We evaluated the association between years of exposure to hypercholesterolemia in early adulthood and future coronary heart disease (CHD) risk.

METHODS AND RESULTS

We examined Framingham Offspring Cohort data to identify adults without incident cardiovascular disease to 55 years of age (n=1478), and explored the association between duration of moderate hyperlipidemia (non-high-density lipoprotein cholesterol ≥ 160 mg/dL) in early adulthood and subsequent CHD. At median 15-year follow-up, CHD rates were significantly elevated among adults with prolonged hyperlipidemia exposure by 55 years of age: 4.4% for those with no exposure, 8.1% for those with 1 to 10 years of exposure, and 16.5% for those with 11 to 20 years of exposure (P<0.001); this association persisted after adjustment for other cardiac risk factors including non-high-density lipoprotein cholesterol at 55 years of age (hazard ratio, 1.39; 95% confidence interval, 1.05-1.85 per decade of hyperlipidemia). Overall, 85% of young adults with prolonged hyperlipidemia would not have been recommended for statin therapy at 40 years of age under current national guidelines. However, among those not considered statin therapy candidates at 55 years of age, there remained a significant association between cumulative exposure to hyperlipidemia in young adulthood and subsequent CHD risk (adjusted hazard ratio, 1.67; 95% confidence interval, 1.06-2.64).

CONCLUSIONS

Cumulative exposure to hyperlipidemia in young adulthood increases the subsequent risk of CHD in a dose-dependent fashion. Adults with prolonged exposure to even moderate elevations in non-high-density lipoprotein cholesterol have elevated risk for future CHD and may benefit from more aggressive primary prevention.

Discordance analysis and the Gordian Knot of LDL and non-HDL cholesterol versus apoB

PURPOSE OF REVIEW

Conventional methods, comparing the concentration of cholesterol to particle number as indices of cardiovascular risk, have not produced consistent results, in large part, because they treat these variables as independent and unrelated. However, although highly correlated, apolipoprotein B particles may contain a normal mass of cholesterol or may be cholesterol-depleted or cholesterol-enriched. Discordance analysis compares the predictive power of LDL-C and non-HDL-C to apolipoprotein B and LDL particle numbers in patients in whom they differ, that is, in whom they are discordant. The advantage of discordance analysis is that the results are not diluted by concordant data in which risk predictions cannot differ.

RECENT FINDINGS

The evidence, to date, consistently demonstrates that apolipoprotein B and LDL particle numbers are more accurate indices of cardiovascular risk than LDL-C or non-HDL-C.

SUMMARY

Discordance analysis is a methodological advance that allows the clinical value of closely correlated variables to be determined and demonstrates that cardiovascular risk is more closely related to the number of atherogenic particles than to the total mass of cholesterol within them.

Influence of low-glucose peritoneal dialysis on serum lipids and apolipoproteins in the IMPENDIA/EDEN trials

BACKGROUND

Glucose, the conventional osmotic agent in peritoneal dialysis (PD) solutions, may contribute to atherogenic dyslipoproteinemia and increased cardiovascular risk.

OBJECTIVE

To determine whether a low-glucose PD regimen may improve the serum lipid and lipoprotein profile in patients with diabetes.

METHODS

A prospective, open-label, parallel group, multinational, randomized, controlled trial with a 6-month follow-up, comprising 251 patients with diabetes receiving PD. Patients were randomized to a low-glucose PD regimen (dextrose-based PD solution plus icodextrin, a starch polymer, and amino acids) or a conventional PD regimen (dextrose PD solutions). Serum lipid and apolipoprotein profiles were determined at baseline and 3 and 6 months.

RESULTS

Serum triglycerides, very low-density-lipoprotein cholesterol, and apolipoprotein B (apoB) decreased significantly in the intervention group at both 3 and 6 months compared with baseline (serum triglycerides: median change at 3 months -0.5 mmol/L, P < .001, at 6 months -0.3 mmol/L, P < .001; very low-density-lipoprotein cholesterol: -0.3 mg/dL, P < .001; -0.3 mg/dL, P < .001; and apoB: -8.5 mg/dL, P < .001; -3.6 mg/dL, P = .043, respectively) and also compared with the control group. In contrast, apoB levels increased significantly in the control group at 3 and 6 months compared with baseline (5.3 mg/dL, P = .041; 5.2 mg/dL, P = .007, respectively). Percentage of patients on lipid-lowering medications at baseline and intensity of therapy was equivalent in each group. The apoB decrease was not affected by lipid-lowering medications in the intervention group.

CONCLUSION

A low glucose-PD regimen significantly improved the atherogenic lipoprotein phenotype compared with PD patients treated with a conventional glucose regimen.