American College of Cardiology Poster Abstract Shows Standard Lipid Profile Inaccurate for LDL Cholesterol Below 70 mg/dL
Friedewald calculation underestimates LDL cholesterol in patients with LDLc less than 70 mg/dL compared to directly measured LDL using VAP® Cholesterol Test
CHICAGO--(BUSINESS WIRE)--Mar 25, 2012 - Science presented today at the American College of Cardiology's (ACC) 61st Annual Scientific Sessions in Chicago reveals the importance of directly measured lipoprotein cholesterol levels, especially in high-risk patients. That's according to the abstract Clinically Meaningful Underestimation of LDLc by Friedewald at Levels Below 70 mg/dL: A Study of 1.3 Million Adults.
Using data supplied by Atherotech Diagnostics Lab, the study examined standard lipid profiles from a clinical sample of 1.34 million adults who were referred between 2009 and 2011 for Atherotech's patented VAP Cholesterol Test using the density gradient ultracentrifugation method. Researchers compared the results of standard lipid profiles, which use the Friedewald formula to estimate LDLc, to results obtained by the VAP Test, which directly measures LDLc.
The independent investigator-initiated research reported clinically meaningful underestimation of LDLc by Friedewald in patients with LDLc <70 mg/dL. Atherotech was not involved in the data analysis.
“This study represents compelling clinical information, particularly for the high-risk, secondary prevention patient with aggressive lipid therapy targets below 70,” said study lead author, Seth S. Martin, M.D. “In such cases, clinicians should strongly consider replacing the standard Friedewald lipid profile with direct lipid measures.”
Martin commented, “the study indicates that clinicians will frequently misclassify patients based on National Cholesterol Education Program Adult Treatment Panel LDLc categories when LDLc is low and triglycerides are elevated using the Friedewald equation to estimate LDLc. While the guidelines currently address this issue by recommending non-HDLc as a secondary treatment target when triglycerides exceed 200 mg/dL, our data clearly demonstrate that this is not enough. Wider use of non-HDLc or apoB is warranted. Further, these direct measures more accurately assess total atherogenic particle burden compared with LDLc, which has important implications for risk assessment.”
Researchers concluded that:
1) Compared with direct measurement, Friedewald LDLc is frequently inaccurate in patients for whom it is routinely used in clinical practice.
2) In crucial secondary prevention dyslipidemia treatment ranges (low LDLc, high TG) as specified by NCEP Adult Treatment Panel (ATP) III Guidelines where there are clinically relevant differences, the magnitude of underestimation in Friedewald LDL is often sufficient to lead to undertreatment.
3) For abnormal TG levels from 150-400 mg/dL — about 28 percent of the population — the reclassification rate is between 25-60 percent.
4) For normal TG levels below 150mg/dL — about 70 percent of the population — the reclassification rate is between 10 and 20 percent.
5) Their results support replacement of Friedewald LDLc in clinical guidelines with direct measures such as non-HDLc or apoB, particularly at secondary prevention target levels.
The study focused on direct versus Friedewald-calculated LDLc, and therefore excluded patients with triglycerides above 400 mg/dL due to known limitations of the Friedewald formula. This yielded a total study population of 1.31 million patients for analysis. Lipid distributions were compared between the Very Large Database of Lipids (VLDL) and the most recent available lipid data from the National Health and Nutrition Examination Survey (NHANES) 2007-2008 showing the VLDL data to be remarkably similar to that of the general population survey.
The VAP Test directly measures cholesterol concentrations of all five major lipoprotein cholesterol classes and their subclasses and identifies a significantly greater number of people at risk for heart disease than the standard cholesterol test. Atherotech provides physicians with a single source for the VAP Test and more than 50 other cardiovascular and metabolic tests. The company provides its unique testing services to physicians, hospitals, clinics and other laboratories throughout the U.S.
About Atherotech Diagnostics Lab
Atherotech is a CLIA-certified clinical reference laboratory and cardiodiagnostic company focusing on cardiometabolic tests, including the company's patented VAP Cholesterol Test, which reports the cholesterol content of all lipids, components and subclasses. The VAP Test is the first cholesterol profile to comply with updated National Cholesterol Education Program ATP III recommendations for direct LDL measurement, which is accurate with non-fasting samples. The VAP Test is available through national and regional diagnostic laboratories and is reimbursed by many of the largest private insurers as well as Medicare. For more information, visit www.Atherotech.com.
Contact: For Atherotech Diagnostics Lab
Armada Medical Marketing
Micki Sievwright, 651-228-1220
Posted: March 2012