Clinically relevant differences were observed in LDL-C levels estimated by the Friedewald, Sampson, and Martin/Hopkins equations in patients with atherosclerotic cardiovascular disease (ASCVD), according to a study published in the Journal of the American College of Cardiology.
Researchers conducted a retrospective analysis of electronic health record data from a large US multistate health care system. Eligible participants were aged 18 years or older, with clinical ASCVD and at least 1 lipid panel with a triglyceride level of less than 400 mg/dL between October 1, 2015, and June 30, 2019.
For each pairwise comparison of equations, the participants were determined to be concordant if their LDL-C was less than 70 mg/dL with both equations and as discordant if the LDL-C was less than 70 mg/dL for the index equation and greater than or equal to 70 mg/dL for the comparator. Data from 146,106 patients (56% men; 91% White; mean age, 68 years) were included.
Participants had a median LDL-C of 81 mg/dL with the Friedewald equation and 84 mg/dL with the Sampson and Martin/Hopkins equations. For those who had triglyceride levels of greater than or equal to 150 mg/dL, the median LDL-C was 86 mg/dL with the Friedewald equation, 92 mg/dL with the Sampson equation, and 97 mg/dL with the Martin/Hopkins equation.
In the 15% of ASCVD patients who had discordance, 9% had an LDL-C of less than 70 mg/dL with the Friedewald equation and an LDL-C of greater than or equal to 70 mg/dL with the Sampson and Martin/Hopkins equations. In addition, 6% had discordance with an LDL-C of less than 70 mg/dL with the Friedewald and Sampson equations and an LDL-C of greater than or equal to 70 mg/dL with the Martin/Hopkins equation.
The discordance rate increased to 41% in participants who had triglyceride levels of greater than or equal to 150 mg/dL. There were increases for both corresponding comparator groups, 23% and 18%, respectively.
Regarding the absolute magnitude of discordance among comparator groups in all ASCVD patients, the difference in estimated LDL-C with the Sampson and Martin/Hopkins equations was 6.3±3.8 mg/dL and 11.8±7.5 mg/dL, respectively. For patients who had triglyceride levels of greater than or equal to 150 mg/dL, this difference in estimated LDL-C increased to 8.2±3.2 mg/dL and 14.8±6.7 mg/dL, respectively.
The investigators noted that their patients were predominantly White and their findings may not be generalizable to other populations with greater racial and ethnic diversity. Also, data related to the timing of ASCVD event, as well as patterns of medication prescription and adherence, were unavailable.
“Whereas the Friedewald and Sampson equations may underestimate LDL-C, resulting in undertreatment of those at increased risk of ischemic events, the Martin/Hopkins equation increases identification of patients who may benefit from more intensive treatment,” the investigators wrote.
Disclosure: One of the study authors declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of authors’ disclosures
Sajja A, Li HF, Spinelli KJ, et al. Discordance between standard equations for determination of LDL cholesterol in patients with atherosclerosis. J Am Coll Cardiol. Published online February 15, 2022. doi: 10.1016/j.jacc.2021.11.042