Basic Lipid Panel Faulted in Heart Disease Risk

The accuracy of the Friedewald equation in calculated LDL cholesterol measurement using the traditional basic lipid panel or standard cholesterol test, has been compared to directly measured LDL-C in the comprehensive commercial VAP Lipid Panel.

Scientists at Johns Hopkins Ciccarone Center (Baltimore, MD, USA) working with colleagues from different institutes, examined consecutive lipid profiles from a clinical sample of 1,340,614 US adults who were 18 years of age or older and whose blood sample underwent vertical spin density gradient ultracentrifugation of cholesterol from 2009 to 2011. The mean age of the patients was 59 years and 52% were women.

Lipid measurements included inverted rate zonal, single vertical spin, density gradient ultracentrifugation by the Vertical Auto Profile (VAP) technique (Atherotech Diagnostics Lab; Birmingham, AL, USA). This technique directly measures LDL-C, very low density lipoprotein cholesterol (VLDL-C), intermediate-density lipoproteins cholesterol (IDL-C), lipoprotein (a) cholesterol (Lp(a)-C), and high density lipoprotein cholesterol (HDL-C). VAP accuracy was examined yearly from 2007 to 2012.

The results of the study showed that the basic lipid panel underestimated risk in 23% to 59% of patients with Friedewald estimated LDL cholesterol levels below 70 mg/dL and triglycerides above 150 mg/dL, which could result in under treatment of high-risk patients.

The authors concluded that the Friedewald equation tends to underestimate LDL-C mainly when accuracy is most crucial, especially if triglycerides are equal to or greater than 150 mg/dL. Friedewald estimation commonly classifies LDL-C as less than 70 mg/dL despite directly measured levels equal to or greater than 70 mg/dL, and therefore additional evaluation is warranted in high-risk patients.

Steven R. Jones, MD, the senior investigator said, "It's the first time we've compared LDL cholesterol measurements using the Friedewald calculation to the density gradient ultracentrifugation method, which directly measures LDL cholesterol. What's important in this study is that Friedewald and direct LDL cholesterol are most different, with Friedewald LDL generally lower than direct LDL, when accuracy is most crucial in patients with LDL cholesterol levels in the high-risk treatment target range and elevated triglycerides." The study was published on March 20, 2013, in the Journal of the American College of Cardiology.

Related Links:
Johns Hopkins Ciccarone Center
Atherotech Diagnostics