Validation of the Martin Method for Estimating Low-Density Lipoprotein Cholesterol Levels in Korean Adults: Findings from the Korea National Health and Nutrition Examination Survey, 2009-2011

Despite the importance of accurate assessment for low-density lipoprotein cholesterol (LDL-C), the Friedewald formula has primarily been used as a cost-effective method to estimate LDL-C when triglycerides are less than 400 mg/dL. In a recent study, an alternative to the formula was proposed to improve estimation of LDL-C. We evaluated the performance of the novel method versus the Friedewald formula using a sample of 5,642 Korean adults with LDL-C measured by an enzymatic homogeneous assay (LDL-CD). Friedewald LDL-C (LDL-CF) was estimated using a fixed factor of 5 for the ratio of triglycerides to very-low-density lipoprotein cholesterol (TG:VLDL-C ratio). However, the novel LDL-C (LDL-CN) estimates were calculated using the N-strata-specific median TG:VLDL-C ratios, LDL-C5 and LDL-C25 from respective ratios derived from our data set, and LDL-C180 from the 180-cell table reported by the original study. Compared with LDL-CF, each LDL-CN estimate exhibited a significantly higher overall concordance in the NCEP-ATP III guideline classification with LDL-CD (p< 0.001 for each comparison). Overall concordance was 78.2% for LDL-CF, 81.6% for LDL-C5, 82.3% for LDL-C25, and 82.0% for LDL-C180. Compared to LDL-C5, LDL-C25 significantly but slightly improved overall concordance (p = 0.008). LDL-C25 and LDL-C180 provided almost the same overall concordance; however, LDL-C180 achieved superior improvement in classifying LDL-C < 70 mg/dL compared to the other estimates. In subjects with triglycerides of 200 to 399 mg/dL, each LDL-CN estimate showed a significantly higher concordance than that of LDL-CF (p< 0.001 for each comparison). The novel method offers a significant improvement in LDL-C estimation when compared with the Friedewald formula. However, it requires further modification and validation considering the racial differences as well as the specific character of the applied measuring method.

尽管低密度脂蛋白胆固醇（low-density lipoprotein cholesterol, LDL-C）的精准评估至关重要，但当甘油三酯水平低于400 mg/dL时，弗雷德瓦尔德公式（Friedewald formula）仍是当前主流的兼具成本效益的LDL-C估算手段。近期有研究提出了该公式的替代方案，以优化LDL-C的估算精度。本研究纳入5642名韩国成年受试者作为研究样本，以酶法均相测定的LDL-C（LDL-CD）作为参考金标准，对比评估了该新型方法与弗雷德瓦尔德公式的性能表现。弗雷德瓦尔德法估算的LDL-C（LDL-CF）通过固定系数5计算甘油三酯与极低密度脂蛋白胆固醇（very-low-density lipoprotein cholesterol, VLDL-C）的比值（TG:VLDL-C ratio）。而新型LDL-C（LDL-CN）的估算值则基于本数据集推导得到的分层特异性TG:VLDL-C中位数比值分别计算：即源自本数据集的LDL-C5、LDL-C25，以及源自原始研究报道的180单元格表的LDL-C180。与LDL-CF相比，各新型LDL-C估算值在与NCEP-ATP III指南的分类一致性上均显著高于LDL-CD（所有对比p<0.001）。整体一致性率方面，LDL-CF为78.2%，LDL-C5为81.6%，LDL-C25为82.3%，LDL-C180为82.0%。相较于LDL-C5，LDL-C25的整体一致性虽有小幅提升，但差异具有统计学意义（p=0.008）。LDL-C25与LDL-C180的整体一致性近乎一致，但在对LDL-C<70 mg/dL的人群进行分类时，LDL-C180的优化效果优于其余估算方法。在甘油三酯水平介于200~399 mg/dL的亚组中，各新型LDL-C估算值的分类一致性均显著高于LDL-CF（所有对比p<0.001）。相较于弗雷德瓦尔德公式，新型方法在LDL-C估算上实现了显著优化，但仍需结合种族差异与检测方法的特性进行进一步改进与验证。