Objectives To explore the association between baseline very low-density lipoprotein cholesterol level (VLDL-C) and 5-year progression of carotid plaque.
Methods Study subjects were recruited from two Chinese cohorts [the People’s Republic of China - United States of America collaborative study (USA-PRC study) and the Chinese multi-provincial cohort study (CMCS)]. A total of 2030 subjects, aged 38 to 74 years, who had complete blood lipids information and B-mode ultrasound of carotid artery examination for both the baseline survey in 2002 and reexamination in 2007 were included in this analysis. Baseline VLDL-C was categorised into three groups according to ATP III criteria: optimal level (VLDL-C < 20 mg/dL), elevated level (VLDL-C = 20∼29 mg/dL) and high level (VLDL-C ≥30 mg/dL). The progression of carotid plaque was defined as the appearance of at least one plaque at reexamination in a previously plaque-free arterial segment.
Results The 5-year progression rate of carotid plaque was 48.5% in all 2030 subjects (men 52.9% vs. women 45.6%). The rates increased with the levels of VLDL-C (43.3%, 50.0%, and 53.9% for the optimal, elevated, and high level group, respectively, P < 0.001). In subjects with normal LDL-C level, the progression rates of carotid plaque also increased with VLDL-C level (38.8%, 41.6%, and 48.9% respectively for the optimal, elevated, and high level group, P = 0.015). In multivariate logistic analysis, the odds ratio for the progression of carotid plaque was 1.40 (95%CI = 1.13-1.74, P = 0.002) after adjusting for age and sex, and 1.29 (95%CI = 1.03-1.61, P = 0.025) after adjusting for other non-lipid risk factors (hypertension, diabetes, obesity and smoking) for high level of VLDL-C compared to low level group. However, the association between VLDL-C and progression of carotid plaque was attenuated and became nonsignificant after further adjustment for LDL-C and/or HDL-C (P > 0.05).
Conclusions The progression rate of carotid plaque was high in the middle-aged and elderly population, and higher rate was found for those with higher baseline VLDL-C, even in subjects with normal LDL-C level. Given the complex relationship among serum lipid components, the role of VLDL-C in the development of atherosclerosis needs further investigation.