👤 Rafael Zubiran

Familial dysbetalipoproteinemia (FDB) is a genetic lipoprotein disorder that can develop in patients homozygous for the APOE2 genotype (ε2/ε2). It is associated with decreased clearance of remnant lipoproteins and increased atherosclerotic cardiovascular disease (ASCVD) risk disproportionate to their level of LDL-C. A goal of this study was to develop a screening test for the ε2/ε2 genotype based on routinely available lipid tests and to determine those at most risk for ASCVD. After assembly of a primary prevention cohort from the UK Biobank (n= 269,895), gene array and exome data was utilized to classify patients as being ε2/ε2 genotype positive or negative. Lipid profiles and APOB levels were extracted and the number of ASCVD events was tabulated during a 15-year follow-up period. Using a newly developed equation for estimating APOB (eAPOB) with lipid panel test results, the ratio of measured APOB to eAPOB was better than any other individual lipid test or ratio for identifying patients with the ε2/ε2 genotype (AUC: APOB/eAPOB: 0.990 (0.986-0.994), nonHDL-C/APOB: 0.961 (0.952-0.970), APOB: 0.955 (0.949-0.961), VLDL/TG: 0.788 (0.771-0.804)). The majority of ε2/ε2 patients could be identified with the APOB/eAPOB ratio even before they expressed the FDB phenotype with elevated TG and nonHDL-C. The PCE or PREVENT risk equations were the most accurate method for identifying higher risk patients (AUC: PREVENT: 0.690 (0.637-0.742), PCE: 0.697 (0.645-0.749)). The APOB/eAPOB ratio can be used to accurately identify the ε2/ε2 genotype and conventional risk equations are the best method for determining those at risk for ASCVD. Show less

A key step in primary prevention is the assessment of atherosclerotic cardiovascular disease (ASCVD) risk. Risk enhancer tests are additional tools used to further improve ASCVD risk assessment over conventional risk markers. Our objective was to determine whether estimated small, dense low-density lipoprotein cholesterol (E-sdLDL-C) can improve risk assessment and serve as a new risk enhancer test. We used a prospective cohort analysis of participants in the UK Biobank study with a median (interquartile range) follow-up of 10 (6.7-12.3) years. We included 271 760 individuals who were not on lipid-lowering medication at baseline and did not have incident ASCVD. The primary study outcome was the incidence of all-cause ASCVD. E-sdLDL-C was strongly associated with ASCVD events with a hazard ratio (HR) of 1.23 (95% CI, 1.22-1.24). After multivariable adjustment for age, sex, systolic blood pressure, hypertension, type 2 diabetes, and blood pressure medications, E-sdLDL-C and ApoB (apolipoprotein B) remained the most significant lipid risk factors (HR, 1.18 [95% CI, 1.16-1.19] and 1.17 [95% CI, 1.16-1.18] per SD, respectively). After further adjustment for ApoB, the association between low-density lipoprotein cholesterol (LDL-C) with all-cause ASCVD was completely reversed with an HR of 0.84 (95% CI, 0.81-0.86), but E-sdLDL-C continued to have a significant positive association with an HR of 1.11 (95% CI, 1.08-1.13). When E-sdLDL-C was discordantly higher than either LDL-C or ApoB, the risk for ASCVD was higher (LDL-C, 31% higher; ApoB, 17% higher). When elevated E-sdLDL-C is coupled with other risk enhancer tests, there is a greater risk for developing ASCVD. In a UK Biobank cohort for primary prevention, the risk of all-cause ASCVD was better captured by E-sdLDL-C than LDL-C. It was also more predictive than LDL-C and ApoB when discordant with these 2 measures. E-sdLDL-C, which can be freely and automatically calculated from a standard lipid panel, can potentially improve ASCVD risk assessment without additional laboratory testing. Show less