Background and aims: This study aimed to evaluate the association between very low levels of low-density lipoprotein (LDL) cholesterol and subsequent clinical outcomes among dyslipidemic patients.
Methods: A retrospective longitudinal study was conducted at a large teaching hospital in Tokyo, Japan, from 2005 to 2018. We included all dyslipidemic adult patients who were followed up at the department of endocrinology. The primary outcome was all-cause mortality and the secondary outcome was cardiovascular disease. We compared the development of these outcomes according to LDL cholesterol categories through longitudinal analyses adjusting for potential confounders.
Results: We included total of 4485 dyslipidemic patients. The mean patient age (standard deviation) was 58.4 (12.2) years, and 2286 patients were men. During a median follow-up of 5.3 (interquartile range 2.2-9.6) years, 252 (5.7%) patients died (25[0.6%] were cardiovascular deaths) and 912 (20.3%) patients developed cardiovascular diseases. Multivariable longitudinal analyses showed that the very low LDL cholesterol group (<60 mg/dl) had significantly higher all-cause mortality than the normal LDL cholesterol group (100-140 mg/dl) (odds ratio[OR] 1.96, 95%confidence interval [CI]:1.22-3.16). Among high-risk patients for atherosclerotic cardiovascular disease (ASCVD), very low LDL cholesterol was significantly associated with increased all-cause mortality (OR 2.61, 95%CI: 1.12-6.10) but decreased incidence of cardiovascular disease (OR 0.47, 95%CI: 0.23-0.93).
Conclusions: Very low LDL cholesterol is associated with increased all-cause mortality but not statistically associated with cardiovascular disease incidence among dyslipidemic patients, regardless of risk. When patients were stratified according to ASCVD risk, this association was more obvious among high-risk patients.
Keywords: Cardiovascular disease; Dyslipidemia; Longitudinal study; Low LDL; Mortality.
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