Low-Density Lipoprotein Cholesterol, Cardiovascular Disease Risk, and Mortality in China

Importance: Limited evidence supports the association between low-density lipoprotein cholesterol (LDL-C) and mortality across different atherosclerotic cardiovascular disease (ASCVD) risk stratifications. Objective: To explore the associations between LDL-C levels and mortality and to identify the optimal ranges of LDL-C with the lowest risk of mortality in populations with diverse ASCVD risk profiles. Design, Setting, and Participants: The ChinaHEART project is a prospective cohort study that recruited residents aged 35 to 75 years from 31 provinces in mainland China between November 2014 and December 2022. Participants were categorized into low-risk, primary prevention, and secondary prevention cohorts on the basis of their medical history and ASCVD risk. Data analysis was performed from December 2022 to October 2023. Main Outcomes and Measures: The primary end point was all-cause mortality, and secondary end points included cause-specific mortality. Mortality data were collected from the National Mortality Surveillance System and Vital Registration. The association between LDL-C levels and mortality was assessed by using Cox proportional hazard regression models with various adjusted variables. Results: A total of 4 379 252 individuals were recruited, and 3 789 025 (2 271 699 women [60.0%]; mean [SD] age, 56.1 [10.0] years) were included in the current study. The median (IQR) LDL-C concentration was 93.1 (70.9-117.3) mg/dL overall at baseline. During a median (IQR) follow-up of 4.6 (3.1-5.8) years, 92 888 deaths were recorded, including 38 627 cardiovascular deaths. The association between LDL-C concentration and all-cause or cardiovascular disease (CVD) mortality was U-shaped in both the low-risk cohort (2 838 354 participants) and the primary prevention cohort (829 567 participants), whereas it was J-shaped in the secondary prevention cohort (121 104 participants). The LDL-C levels corresponding to the lowest CVD mortality were 117.8 mg/dL in the low-risk group, 106.0 mg/dL in the primary prevention cohort, and 55.8 mg/dL in the secondary prevention cohort. The LDL-C concentration associated with the lowest all-cause mortality (90.9 mg/dL vs 117.0 mg/dL) and CVD mortality (87 mg/dL vs 114.6 mg/dL) were both lower in individuals with diabetes than in individuals without diabetes in the overall cohort. Conclusions and Relevance: This study found that the association between LDL-C and mortality varied among different ASCVD risk cohorts, suggesting that stricter lipid control targets may be needed for individuals with higher ASCVD risk and those with diabetes.