Implications of Cardiac Risk and Low-Density Lipoprotein Cholesterol Distributions in the United States for the Diagnosis and Treatment of Dyslipidemia

Abstract Background Low-density lipoprotein cholesterol (LDL-C) is an established risk factor for cardiovascular disease (CVD), and a target for lipid-lowering therapy. LDL-C is typically not measured directly but is estimated using the Friedewald formula, which assumes a fixed factor for the ratio of triglycerides (TG) to very low-density lipoprotein cholesterol (VLDL-C). However this assumption is sometimes not valid. The Martin/Hopkins (M/H) formula estimates LDL-C using an adjustable factor for the TG:VLDL-C ratio and is expected to improve upon Friedewald when predicting measured LDL-C, and apolipoprotein B (ApoB), one molecule of which is associated with each LDL particle. Purpose We compared values of LDL-C calculated by the Friedewald and M/H methods with respect to their correlation with non-high density lipoprotein cholesterol (non-HDL-C) and ApoB, and their classification of individuals based upon attainment of the threshold value of 70 mg/dl (1.8 mmol/l) of LDL-C. This cut-point is a treatment target for individuals at high risk of CVD in the 2019 ESC guidelines for lipid modification, and a threshold for initiating statin therapy in the 2019 ACC/AHA guidelines. Methods In this analysis we included participants in the National Health and Nutrition Examination Survey (NHANES) from 2005–2016, age ≥18, <80 years who had measurements for total cholesterol (TC), TG and HDL-C. LDL-C was calculated using Friedewald and M/H. We correlated LDL-C (calculated using the two methods) with non-HDL-C and ApoB. We identified individuals with LDL-C <70 mg/dl using both methods. When LDL-C (Friedewald) was <70, but LDL-C (M/H) was >70, we classified these participants as discordant. Statistical analyses were performed in IBM SPSS for Windows v26. Results 12,243 individuals were included. 51.8% were female, mean (±SD) age was 45.5±17.4, 15.3% were treated with statins, ApoB was available for 2179 participants. Mean lipid concentrations (mg/dl) were: TC: 191.5±41.0, TG: 120.0±67.0, HDL-C: 54.1±15.7, LDL-C (Friedewald): 113.3±35.4; LDL-C (M/H): 114.9±35.2. In the whole population, LDL-C (M/H) was more strongly correlated than LDL-C (Friedewald) with ApoB (r=0.935 v 0.894) and non-HDL-C (r=0.981 v 0.944). In statin-treated participants, LDL-C (M/H) was also more strongly correlated with ApoB (r=0.951 v 0.914) and non-HDL-C (r=0.979 v 0.928). 1139 participants had LDL-C (Friedewald) <70 mg/dl. Of these, 206 individuals (18.1%) were discordant, having LDL-C (M/H) >70 mg/dl. Amongst statin-treated patients, 22.9% were discordant. Only 5.5% of individuals with LDL-C (M/H) <70 mg/dl showed reverse discordance (LDL-C (Friedewald) >70 mg/dl). Conclusions The M/H method of calculating LDL-C correlates more strongly with non-HDL-C and ApoB than Friedewald. Importantly the discordant results confirm previous observations that Friedewald underestimates LDL-C at low concentrations. This may result in under-use of lipid-lowering therapies. Funding Acknowledgement Type of funding source: None

Download Full-text

Omega-3 Fatty Acids for the Management of Hypertriglyceridemia: A Science Advisory From the American Heart Association

Circulation ◽

10.1161/cir.0000000000000709 ◽

2019 ◽

Vol 140 (12) ◽

Cited By ~ 65

Author(s):

Ann C. Skulas-Ray ◽

Peter W.F. Wilson ◽

William S. Harris ◽

Eliot A. Brinton ◽

Penny M. Kris-Etherton ◽

...

Keyword(s):

Low Density Lipoprotein ◽

Density Lipoprotein ◽

Heart Association ◽

The United States ◽

Lipoprotein Cholesterol ◽

Low Density ◽

Omega 3 Fatty Acids ◽

Omega 3 ◽

Low Density Lipoprotein Cholesterol ◽

Very High

Hypertriglyceridemia (triglycerides 200–499 mg/dL) is relatively common in the United States, whereas more severe triglyceride elevations (very high triglycerides, ≥500 mg/dL) are far less frequently observed. Both are becoming increasingly prevalent in the United States and elsewhere, likely driven in large part by growing rates of obesity and diabetes mellitus. In a 2002 American Heart Association scientific statement, the omega-3 fatty acids (n-3 FAs) eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) were recommended (at a dose of 2–4 g/d) for reducing triglycerides in patients with elevated triglycerides. Since 2002, prescription agents containing EPA+DHA or EPA alone have been approved by the US Food and Drug Administration for treating very high triglycerides; these agents are also widely used for hypertriglyceridemia. The purpose of this advisory is to summarize the lipid and lipoprotein effects resulting from pharmacological doses of n-3 FAs (>3 g/d total EPA+DHA) on the basis of new scientific data and availability of n-3 FA agents. In treatment of very high triglycerides with 4 g/d, EPA+DHA agents reduce triglycerides by ≥30% with concurrent increases in low-density lipoprotein cholesterol, whereas EPA-only did not raise low-density lipoprotein cholesterol in very high triglycerides. When used to treat hypertriglyceridemia, n-3 FAs with EPA+DHA or with EPA-only appear roughly comparable for triglyceride lowering and do not increase low-density lipoprotein cholesterol when used as monotherapy or in combination with a statin. In the largest trials of 4 g/d prescription n-3 FA, non–high-density lipoprotein cholesterol and apolipoprotein B were modestly decreased, indicating reductions in total atherogenic lipoproteins. The use of n-3 FA (4 g/d) for improving atherosclerotic cardiovascular disease risk in patients with hypertriglyceridemia is supported by a 25% reduction in major adverse cardiovascular events in REDUCE-IT (Reduction of Cardiovascular Events With EPA Intervention Trial), a randomized placebo-controlled trial of EPA-only in high-risk patients treated with a statin. The results of a trial of 4 g/d prescription EPA+DHA in hypertriglyceridemia are anticipated in 2020. We conclude that prescription n-3 FAs (EPA+DHA or EPA-only) at a dose of 4 g/d (>3 g/d total EPA+DHA) are an effective and safe option for reducing triglycerides as monotherapy or as an adjunct to other lipid-lowering agents.

Download Full-text