Low Density Lipoprotein Cholesterol Is Associated With Increased Risk of Cardiovascular Disease in Participants Over 70 Years Old: A Prospective Cohort Study

Abstract BackgroundPrevious studies, in which the data were collected about half a century ago, suggested that elevated low density lipoprotein cholesterol (LDL-C) is not associated with increased risk of cardiovascular disease (CVD) in patients over 70 years old. However, what is the relationship between LDL-C and CVD risk in a contemporary population aged over 70 years has not been well examined in China.MethodsThe China Health and Retirement Longitudinal Study (CHARLS) is an ongoing nationally representative study. In this analysis, participants of CHARLS who did not taking statins and did not have heart disease and stroke at 2011 were include and were followed up to 2018. The outcome of this analysis was occurrence of CVD at follow up, which include heart disease and stroke. Cox regression was used to assess the harmful effect of LDL-C on CVD occurrence. We calculated e-values to quantify the effect of unmeasured confounding on our results.ResultsOf the 9,631 participants, 15.2% (N=1,463) were aged over 70 years and 52.5% (N=5,060) were female. During the 7 years follow-up, 1,437 participants had a first CVD attack. Risk of CVD occurrence increased 8% with each 10 mg/mL elevation in LDL-C in whole participants (adjusted HR, 1.08; 95% CI, 1.06-1.10) and age groups of ≥70 years, 60-69years and <60 years. Similar results were observed in subgroup analyses, in which participants were stratified by sex, hypertension, diabetes and chronic kidney disease. According to the restricted cubic spline, we noted a U-shaped relationship between LDL-C and risk of CVD occurrence in group over 70 years old, however, we further found that in the left side of U-shape curve, LDL-C was not associated with occurrence of CVD and its attribution to CVD occurrence was only 2.1%, which indicated that lower level of LDL-C could not increase the risk of CVD occurrence as it was demonstrated by a U-shape association. E-value analysis suggested robustness to unmeasured confounding.ConclusionsIn contemporary society of China, elevated the level of LDL-C also increased the risk of CVD in participants over 70 years old as in the relatively younger participants. These results should strengthen guideline recommendations for the use of lipid lowering therapies in those elderly.