Estimating LDL Cholesterol
LDL cholesterol (LDL-C)3 is an important modifiable risk factor for atherosclerotic cardiovascular disease. It is primarily calculated via the Friedewald equation, which uses total cholesterol (TC), HDL cholesterol (HDL-C), and triglycerides (TG) to calculate LDL-C (LDL-C TC HDL-TG/5).
However, a newly derived equation for LDL-C estimation was recently published that addressed limitations in the commonly used Friedewald LDL-C calculation method. The novel method was reported to classify patients with superior concordance to measured LDL-C compared to the Friedewald method, particularly in patients with LDL-C <70 mg/dL.
Mayo Clinic researchers, Jeff Meeusen, Ph.D., Alan Lueke, Allan Jaffe, M.D., and Amy Saenger, Ph.D., completed a recently published study in Clinical Chemistry to evaluate the performance of the novel method. The study included an independent cohort of 23 055 patients with LDL-C measured by the gold standard β-quantification reference method.
The results indicated that Friedewald underestimated and the novel method overestimated measured LDL-C. Both estimations significantly deviated from the reference method when LDL-C was <70 mg/dL. Overall, the Friedewald and novel calculations correctly classified 77% and 78% of patients, respectively. The largest discrepancy in classification was observed in individuals with measured LDL-C <70 mg/dL. For this group the novel calculation would reclassify 8.7% of patients as >70 mg/dL compared to the Friedewald equation.
Based on these results, Mayo Clinic researchers concluded that the novel method has some benefits but it is unclear whether improvements over the Friedewald calculation are substantive enough to justify making the change in routine clinical practice and to improve patient outcomes.