Validation of multiple equations for estimating low-density lipoprotein cholesterol levels in Korean adults.

Background: Limited data are available for validation of low-density lipoprotein cholesterol (LDL) calculation (LDL) in the adult Korean population. The aim of this study was to develop and validate a new equation for LDL and to compare it with previous such equations in a Korean population.

Methods: A new equation for LDL was developed (LDL). LDL and 11 other previously published equations were applied and compared with directly measured LDL concentration (LDL) in a development cohort (population 1), an independent validation cohort in the same laboratory (population 2), and the Korea National Health and Nutrition Examination Survey 2017 cohort (population 3).

Results: Among the 12 equations, the newly-developed equation (LDL = total cholesterol - 0.87 x high-density lipoprotein cholesterol - 0.13 x triglycerides) had the highest intraclass correlation coefficient (ICC) and the lowest mean systemic difference and median absolute percentage error in populations 1 and 2 but not in population 3. Subgroup analysis showed good agreement between LDL and LDL (ICC > 0.75) in population 2, whose LDL < 70 mg/dL. For samples with high triglycerides (> 400 mg/dL), equation accuracy varied. Categorization concordance according to the National Cholesterol Education Program Adult Treatment Panel III criteria with the other 11 equations were less than 80%; that of LDL was 87.6 and 87.4% in populations 1 and 2, respectively.

Conclusions: Accuracy of 12 equations for LDL varied by cohort and subgroup based on LDL and triglycerides. A laboratory-specific equation for LDL and/or LDL may be needed for accurate evaluation of LDL status.