Evaluation of small dense low-density lipoprotein cholesterol detection by the direct clearance method and its preliminary clinical application

Abstract

Objective To verify and valuate the performance of small dense low-density lipoprotein cholesterol (sdLDL-C) detection by the direct clearance method and evaluate its preliminary clinical application in acute coronary syndrome(ACS). Methods Case control study: The performance (accuracy, precision, linearity) of sdLDL-C was assessed by direct clearance method.In 143 cases of ACS patients selected from Cardiology Department and Emergency Department of Shangdong Provincial Hospital from April to October in 2016, with 100 cases male, female 43 cases, including acute myocardial infarction (AMI) group of 59 cases, unstable angina pectoris (UAP) group of 84 cases; 83 cases of healthy volunteers as a control group selected from health physical examination center of Shandong Provincial Hospital, with 59 cases male, female 24 cases. Levels of sdLDL-C, total cholesterol (TCH), triglyceride (TG), low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), apolipoprotein A (ApoA I), apolipoprotein B (ApoB), lipoprotein (a) (Lpa) and high sensitive C-reactive protein (Hs-CRP) were detected separately by automatic biochemical analyzer. Non high density lipoprotein cholesterol (non-HDL-C) equals TCH minus HDL-C. χ2 test, t test, one-way ANOVA, Pearson correlation and multiple linear regression analysis were used as statistical methods. Results The within-lot or between-lot variation was 2.85% and 3.36%.Methodological comparison: regression equation Y=0.984X+ 0.018, r2=0.966, t=-0.191, P=0.850. There was a good linear correlation(Y=1.026X+ 0.007, r2=0.999) between theoretical values and actual detection results in range of 0.15-2.65 mmol/L. SdLDL-C concentrations were positive correlated with TCH, non-HDL, LDL-C, TG, ApoB(r=0.758, 0.848, 0.839, 0.514, 0.885, respectively, P 0.05). Multiple linear regression analysis showed that the factors influencing sdLDL-C level were HDL-C, ApoB, LDL-C and TG. The levels of sdLDL-C, TG in the ACS group were significantly higher than those in the control group (t=3.415, 4.660, respectively, P 0.05). Comparing AMI group with control group, sdLDL-C, TG and Hs-CRP were significantly higher than the control group (P=0.000, 0.000, 0.000, respectively), but TCH, LDL-C and non-HDL were similar between the two groups (P=0.800, 0.320, 0.120, respectively); Comparing UAP group with control group, TG and Hs-CRP were higher than control group (P=0.001, 0.047, respectively), TCH and LDL-C were significantly lower than the control group(P=0.003, 0.008, respectively), but sdLDL-C had no difference (P=0.305); Comparing AMI group with UAP group, sdLDL-C, TCH, LDL-C and Hs-CRP were significantly higher than UAP group (P=0.000, 0.003, 0.001, 0.000, respectively), and TG were no statistical significance (P=0.473). Conclusions Direct clearance method can meet the requirement of sdLDL-C detection. sdLDL-C level can assess the metabolism of blood lipids and be used as an independent risk factor and predictive index of ACS, superior to LDL-C.(Chin J Lab Med, 2017, 40: 253-259) Key words: Acute coronary syndrome; Cholesterol, LDL; Lipid metabolism