Abstract 17196: An Improved Equation for Estimation of LDL Cholesterol in European and African American Adults
Introduction: The Friedewald equation (FE) has been the US standard for estimating LDL-cholesterol (LDL-C) levels when direct measures are not available, but loses accuracy at triglyceride (TG) levels ≥400 mg/dL. A new formula (Chen et al) has been shown to more accurately estimate LDL-C across the range of TG, including values ≥400 mg/dL in a Chinese population. We tested the new Chen formula (CF) and the FE against LDL-C measured by NMR spectroscopy in European (EA) and African American (AA) adults.
Methods and Results: The sample consisted of 937 apparently healthy subjects ages 31 to 75 years (51.3 ± 8.1 years; 58.3% female; 47.2 EA, 52.8 % AA). Blood was obtained in fasting subjects and total cholesterol (TC), HDL cholesterol (HDL-C), and TG were measured using standard enzymatic methods; LDL-C was estimated using both the FE, [(LDL-C)=(TC)-(HDL-C)-(TG/5)], and the CF [(LDL-C)=0.9[(TC)-(HDL-C)] - 0.1(TG)]. LDL-C was also measured directly using proton NMR spectroscopy (NMR) as the reference standard. Overall mean LDL-C was 130.2 ± 40.mg/dL 1 for FE and 128.6 ± 36.5 mg/dL for CF, p=<0.0001 for correlation (r2= 0.95). The % error for each the FE and CF against NMR LDL-C is plotted against TG levels (log) in the Figure. The FE underestimates NMR LDL-C as TG increases, (beta -1.6% error per 10% higher TG), whereas the CF only slightly overestimates NMR LDL-C at higher values of TG (beta 0.5% error per 10% higher TG) and remains accurate at levels ≥400 mg/dL.
Conclusion: The CF more accurately estimates LDL-C compared with the FF across all TG values and remains accurate for levels ≥400 mg/dL in both races. Thus, the Chen formula may offer improved LDL-C estimation utility in African American and European American adults, particularly for TG levels ≥400 mg/dL, when direct measurement of LDL-C is not accessible or cost prohibitive. Figure: Friedewald Equation and Chen Formula Estimates of LDL-C Across TG Levels
- © 2011 by American Heart Association, Inc.