LDL cholesterols levels after statin treatment: A comparison of measured vs. estimated values

Kim, Hyeon Jin; Suk, Ji Hye; Kang, Ji Hyun; Kwon, Hyuk Yong; Hwang, Chi Sung; Kim, Myoung Joon; Kim, Mi Kyung; Kim, Tae Ik; Kim, In Joo

Abstract

BACKGROUND/AIMS
Lowering low-density lipoprotein cholesterol (LDL-C) is the primary target for the prevention of cardiovascular disease. Previous studies have shown that estimated LDL-C levels calculated using Friedewald's formula (FLDL-C) are closely correlated with directly measured LDL-C levels (DLDL-C). However, because statins not only reduce LDL-C, but also alter the levels of parameters used to calculate FLDL-C (i.e., total cholesterol, triglycerides, and high-density lipoprotein cholesterol), whether calculated LDL-C levels remain a reliable estimate of actual levels after statin treatment is unclear.
METHODS
Subjects included 985 patients at high risk of cardiovascular disease who had taken statins for more than 6 months. FLDL-C data were compared to DLDL-C data.
RESULTS
A strong correlation was observed between DLDL-C and FLDL-C data (R2=0.879). However, the absolute values for FLDL-C and DLDL-C differed significantly according to a paired t-test, and 42.3% of patients showed a difference of greater than 10% between these two values. Among patients with diabetes, the percentage of patients deemed to have achieved target LDL-C levels differed significantly according to the method of LDL-C determination (p=0.007).
CONCLUSIONS
FLDL-C and DLDL-C data remained well correlated after statin treatment, although the absolute values differed significantly according to the LDL-C determination method. Furthermore, the percentage of subjects deemed to achieve target LDL-C levels differed significantly according to the method of determination among patients with diabetes.