Association Between LDL-C/HDL-C Ratio and Long-term Carotid Plaque Risk in middle-aged and elderly Rural Populations: A Prospective Population Study

Yingzhe Shao¹Juan Hao¹Hailu Zhang²Yixin Chen³Jun Tu^1,4,5,6Xianjia Ning^1,4,5,6*Yan Li^7*

• ¹Department of Neurology, Tianjin Medical University General Hospital, Tianjin, China
• ²Department of Oncology, Tianjin Jizhou People’s Hospital, Tianjin, China
• ³School of Basic Medical Sciences, Tianjin Medical University, Tianjin, China
• ⁴Institute of Clinical Epidemiology & Evidence-Based Medicine, Tianjin Jizhou People’s Hospital, Tianjin, China
• ⁵Laboratory of Epidemiology, Tianjin Neurological Institute, Tianjin, China
• ⁶Tianjin Neurological Institute, Key Laboratory of Post-Neuroinjury Neuro-repair and Regeneration in Central Nervous System, Ministry of Education and Tianjin City, Tianjin, China
• ⁷Tianjin Medical University Jizhou Clinical College; Institute of Clinical Epidemiology & Evidence-Based Medicine, Tianjin Jizhou People’s Hospital, Tianjin, China

Background: Atherosclerotic cardiovascular and cerebrovascular diseases are still the main cause of global incidence rate and mortality. The LDL-C/HDL-C ratio (LHR) has been identified as a potential biomarker for cardiovascular risk. However, the relationship between it and the long-term risk of carotid plaques is not yet clear, especially in low-income populations in China. Methods: This prospective cohort study included adults aged ≥45 years without carotid plaque at baseline from low-income rural areas of Tianjin, China. Baseline characteristics were collected in 2014, and follow-up data were obtained in 2019. The primary outcome was the development of new carotid plaques, assessed using carotid ultrasound. The relationship between the LDL-C/HDL-C ratio (LHR) and new carotid plaques was analyzed using multifactorial logistic regression, with the presence or absence of new-onset plaques as the dependent variable. Additionally, we utilized restricted cubic spline (RCS) regression to visually present the potential nonlinear relationship between LHR and the risk of carotid plaque. Results: Over the six-year follow-up period, 606 participants (38.3%) developed new carotid plaques. Higher LHR was significantly associated with an increased risk of new carotid plaques, with each unit increase in LHR corresponding to a 35.9% higher risk (OR = 1.359, 95% CI: 1.180-1.566, P < 0.001). The RCS curve indicated a non-linear positive association between LHR and the likelihood of carotid plaques (P for non-linearity = 0.019), with an optimal cut-off at 1.257. Logistic regression analysis confirmed that LHR > 1.257 was linked to increased odds of carotid plaques in both unadjusted (OR: 1.80, P < 0.001) and adjusted models (OR: 1.835, P < 0.001), with LHR≤ 1.257 serving as the reference. In subgroup analysis, all subgroups consistently demonstrated a significant association between increased LHR (all OR > 1). Conclusions: The research results indicate that there is a non-linear positive correlation between LHR and the long-term risk of carotid plaques in middle-aged and elderly populations, suggesting that LHR may be an effective indicator for screening carotid plaques in grassroots middle-aged and elderly populations.