Differential age-specific associations of LDL cholesterol and body mass index with coronary heart disease

Background and aims: Low-density lipoprotein cholesterol (LDLc) and body mass index (BMI) are not always correlated and their relationship is probably dependent on age, indicating differential age-specific associations of these factors with health outcomes. We aim to discriminate the roles of LDLc and BMI in coronary heart disease (CHD) across different age groups. Methods: This is a prospective cohort study of 368,274 participants aged 38-73 years and free of CHD at baseline. LDLc and BMI were measured at baseline, and incident CHD was the main outcome. Cox proportional hazards model and restricted cubic spline (RCS) regression were used to estimate hazard ratio (HR) and 95% confidence interval (CI) of exposure on CHD. Results: After a mean of 12 years of follow-up, similar relationships of LDLc and BMI with CHD risk were observed in the overall population but in differential age-specific patterns. Across the age groups of <50, 50-54, 55-59, 60-64 and >= 65 years, the LDLc-CHD association diminished with the adjusted HRs decreasing from 1.35, 1.26, 1.19, 1.11 to 1.08; while no declining trend was found in BMI-CHD relationship with the adjusted HRs of 1.15, 1.11, 1.12, 1.13 and 1.15, respectively. The interaction and mediation between LDLc and BMI on CHD risk were more pronounced at young-age groups. LDLc-CHD but not BMI-CHD association was dependent on sex, metabolic syndrome and lipid-lowering drugs use. Conclusions: There were differential age-specific associations of LDLc and BMI with the risk of developing CHD, calling for future efforts to discriminate the age-different benefits from lipids management or weight control on the primary prevention for CHD.