title: Validation of a proposed novel equation for estimating LDL cholesterol.
abstract: BACKGROUND
  Aggressive LDL cholesterol (LDL-C)-lowering strategies are recommended for primary and secondary prevention of cardiovascular events. 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.
  
  
  METHODS
  We evaluated the performance of the novel method within an independent cohort of 23 055 patients with LDL-C measured by the gold standard β-quantification reference method.
  
  
  RESULTS
  Overall 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.
  
  
  CONCLUSIONS
  We compared both novel and Friedewald estimated LDL-C against the LDL-C reference method; in contrast, the prior study relied on validation of a subset of samples by β-quantification to allow the use of the vertical autoprofile method for LDL-C measurement. We conclude 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.
authors.affiliation: Division of Clinical Core Laboratory Services, Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN;
authors.forename: Jeffrey W
authors.initials: JW
authors.lastname: Meeusen
authors.affiliation: Division of Clinical Core Laboratory Services, Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN;
authors.forename: Alan J
authors.initials: AJ
authors.lastname: Lueke
authors.affiliation: Division of Clinical Core Laboratory Services, Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN; Division of Cardiovascular Diseases, Department of Medicine, Mayo Clinic, Rochester MN. jaffe.allan@mayo.edu.
authors.forename: Allan S
authors.initials: AS
authors.lastname: Jaffe
authors.affiliation: Division of Clinical Core Laboratory Services, Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN;
authors.forename: Amy K
authors.initials: AK
authors.lastname: Saenger
mesh_terms: D000293:Adolescent; D000328:Adult; D002648:Child; D008076:Cholesterol, HDL / Q000097:blood; D008078:Cholesterol, LDL / Q000097:blood*; D015331:Cohort Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D014280:Triglycerides / Q000097:blood; D055815:Young Adult
chemical_list: D008076:Cholesterol, HDL; D008078:Cholesterol, LDL; D014280:Triglycerides