Association and its population heterogeneities between low-density lipoprotein cholesterol and all-cause and cardiovascular mortality: A population-based cohort study

Background: The association and its population heterogeneities between low-density lipoprotein cholesterol (LDL-C) and all-cause and cardiovascular mortality remain unknown. We aimed to examine the dose-dependent associations of LDL-C levels with specific types of cardiovascular disease (CVD) mortality and heterogeneities in the associations among different population subgroups. Methods: A total of 2,968,462 participants aged 35-75 years from China Health Evaluation And risk Reduction through nationwide Teamwork (ChinaHEART) (2014-2019) were included. Cox proportional hazard models and Fine-Gray subdistribution hazard models were used to estimate associations between LDL-C categories (<70.0, 70.0-99.9, 100.0-129.9 [reference group], 130.0-159.9, 160.0-189.9, and >= 190.0 mg/dL) and all-cause and cause-specific mortality. Results: During a median follow-up of 3.7 years, 57,391 and 23,241 deaths from all-cause and overall CVD were documented. We observed J-shaped associations between LDL-C and death from all-cause, overall CVD, coronary heart disease (CHD), and ischemic stroke, and an L-shaped association between LDL-C and hemorrhagic stroke (HS) mortality (P for non-linearity <0.001). Compared with the reference group (100.0-129.9 mg/dL), very low LDL-C levels (<70.0 mg/dL) were significantly associated with increased risk of overall CVD (hazard ratio [HR]: 1.10, 95% confidence interval [CI]: 1.06-1.14) and HS mortality (HR: 1.37, 95% CI: 1.29-1.45). Very high LDL-C levels (>= 190.0 mg/dL) were associated with increased risk of overall CVD (HR: 1.51, 95% CI: 1.40-1.62) and CHD mortality (HR: 2.08, 95% CI: 1.92-2.24). The stronger associations of very low LDL-C with risk of CVD mortality were observed in individuals with older age, low or normal body mass index, low or moderate 10-year atherosclerotic CVD risk, and those without diagnosed CVD or taking statins. Stronger associations between very high LDL-C levels and all-cause and CVD mortality were observed in younger people. Conclusions: People with very low LDL-C had a higher risk of all-cause, CVD, and HS mortality; those with very high LDL-C had a higher risk of all-cause, CVD, and CHD mortality. On the basis of our findings, comprehensive health assessment is needed to evaluate cardiovascular risk and implement appropriate lipid-lowering therapy for people with very low LDL-C.