Validation of a Newly Developed Equation for Estimating Serum Apolipoprotein B: Associations with Cardiovascular Disease Surrogate Markers in Koreans

PURPOSE: Many clinical guidelines recommend apolipoprotein B (apoB) measurement, particularly in subjects with metabolic syndrome or type 2 diabetes. Recently, we developed a new equation to estimate serum apoB (apoBE). We validated the clinical relevance of apoBE and compared the performance of the equation with conventional lipid measurements and direct measurement of apoB. MATERIALS AND METHODS: Study subjects were recruited from patients who visited the Health Screening Center at Kangbuk Samsung Hospital between January and December 2009 for routine medical examinations (n=78125). For analysis of coronary calcium score, we recruited study subjects from the same institution between January 2007 and December 2010 (n=16493). RESULTS: apoBE was significantly correlated with serum high-sensitivity C-reactive level {r=0.18 [95% confidence interval (CI), 0.18–0.19]} in partial correlation analysis adjusted for age, sex, and body mass index. apoBE was associated with a Framingham risk score indicating more than moderate risk (10-year risk ≥10%), the presence of microalbuminuria, and the presence of coronary artery calcium in multivariate logistic regression analysis. These associations were comparable to those of directly-measured serum apoB [odds ratio per 1 SD 3.02 (2.75–3.27) vs. 2.70 (2.42–3.02) for a Framingham risk score indicating more than moderate risk, 1.31 (1.21–1.41) vs. 1.35 (1.25–1.45) for the presence of microalbuminuria, and 1.33 (1.26–1.41) vs. 1.31 (1.23–1.38) for the presence of coronary calcium score respectively]. These findings were also consistently observed in subgroup analysis for subjects with type 2 diabetes. CONCLUSION: The associations between cardiovascular surrogate markers and apoBE were comparable to those of directly-measured apoB.