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(cal)) in the adult Korean population. The aim of this study was to develop and validate a new equation for LDL(cal) and to compare it with previous such equations in a Korean population. METHODS: A new equation for LDL(cal) was developed (LDL(Choi)). LDL(Choi) and 11 other previously published equations were applied and compared with directly measured LDL concentration (LDL(direct)) 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(Choi) = 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(Choi) and LDL(direct) (ICC > 0.75) in population 2, whose LDL(direct) < 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(Choi) was 87.6 and 87.4% in populations 1 and 2, respectively. CONCLUSIONS: Accuracy of 12 equations for LDL(cal) varied by cohort and subgroup based on LDL(direct) and triglycerides. A laboratory-specific equation for LDL(cal) and/or LDL(direct) may be needed for accurate evaluation of LDL status. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12944-021-01525-6.