Low LDL-C levels are associated with risk of mortality in a Chinese cohort study

Background and aims Although low-density lipoprotein cholesterol (LDL-C) has been considered as a risk factor of atherosclerotic cardiovascular disease, limited studies can be available to evaluate the association of LDL-C with risk of mortality in the general population. This study aimed to examine the association of LDL-C level with risk of mortality using a propensity-score weighting method in a Chinese population, based on the health examination data. Methods We performed a retrospective cohort study with 65,517 participants aged 40 years or older in Ningbo city, Zhejiang. LDL-C levels were categorized as five groups according to the Chinese dyslipidemia guidelines in adults. To minimize potential biases resulting from a complex array of covariates, we implemented a generalized boosted model to generate propensity-score weights on covariates. Then, we used Cox proportional hazard regression models with all-cause and cause-specific mortality as the dependent variables to estimate hazard ratios (HRs) and 95% confidence intervals (95% CIs). Results During the 439,186.5 person years of follow-up, 2403 deaths occurred. Compared with the median LDL-C group (100–130 mg/dL), subjects with extremely low LDL-C levels (group 1) had a higher risk of deaths from all-cause (HR = 2.53, 95% CI:1.80–3.53), CVD (HR = 1.84, 95% CI: 1.28–2.61), ischemic stroke (HR = 2.29, 95% CI:1.32–3.94), hemorrhagic stroke (HR = 3.49, 95% CI: 1.57–7.85), and cancer (HR = 2.12, 95% CI: 1.04–4.31) while the corresponding HRs in LDL-C group 2 were relatively lower than that in group 1. Conclusions Low LDL-C levels were associated with an increased risk of all-cause, CVD, ischemic stroke, hemorrhagic stroke, and cancer mortality in the Chinese population.