Discordance Between Standard Equations for Determination of LDL Cholesterol in Patients With Atherosclerosis.

Sajja A, Li HF, Spinelli KJ, Blumenthal RS, Virani SS, Martin SS, Gluckman TJ. Discordance Between Standard Equations for Determination of LDL Cholesterol in Patients With Atherosclerosis. Journal of the American College of Cardiology. 2022 Feb 15; 79(6):530-541.

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Abstract:

BACKGROUND: Accurate estimation of low-density lipoprotein cholesterol (LDL-C) is important for guiding cholesterol-lowering therapy. Different methods currently exist to estimate LDL-C. OBJECTIVES: This study sought to assess discordance of estimated LDL-C using the Friedewald, Sampson, and Martin/Hopkins equations. METHODS: Electronic health record data from patients with atherosclerotic cardiovascular disease and triglyceride (TG) levels of  < 400 mg/dL between October 1, 2015, and June 30, 2019, were retrospectively analyzed. LDL-C was estimated using the Friedewald, Sampson, and Martin/Hopkins equations. Patients were categorized as concordant if LDL-C was  < 70 mg/dL with each pairwise comparison of equations and as discordant if LDL-C was  < 70 mg/dL for the index equation and  = 70 mg/dL for the comparator. RESULTS: The study included 146,106 patients with atherosclerotic cardiovascular disease (mean age: 68 years; 56% male; 91% White). The Martin/Hopkins equation consistently estimated higher LDL-C values than the Friedewald and Sampson equations. Discordance rates were 15% for the Friedewald vs Martin/Hopkins comparison, 9% for the Friedewald vs Sampson comparison, and 7% for the Sampson vs Martin/Hopkins comparison. Discordance increased at lower LDL-C cutpoints and in those with elevated TG levels. Among patients with TG levels of  = 150 mg/dL, a > 10 mg/dL difference in LDL-C was present in 67%, 27%, and 23% of patients when comparing the Friedewald vs Martin/Hopkins, Friedewald vs Sampson, and Sampson vs Martin/Hopkins equations, respectively. CONCLUSIONS: Clinically meaningful differences in estimated LDL-C exist among equations, particularly at TG levels of  = 150 mg/dL and/or lower LDL-C levels. Reliance on the Friedewald and Sampson equations may result in the underestimation and undertreatment of LDL-C in those at increased risk.