Correlation of Triglyceride Levels on Low-Density Lipoprotein Cholesterol Calculation Values Compared with Direct Measurement Method

Abstract

Objective    : To study the correlation of triglyceride levels to calculated LDL-c by  comparing the LDL-c values obtained from calculation and direct measurement method.

Method       : Observational-analytical research. 36,471 samples were analyzed the lipid profile during 1 October 2017 to 30 September 2018. Data collecting include  age, gender, cholesterol, triglyceride, high density lipoprotein cholesterol(HDL-c) and direct LDL-c then calculated LDL-c was derived by formula of Friedewald, Anandaraja, Puavilai, Chen and Vujovic. Data were analyzed with descriptive statistics, correlation coefficient, pair t-test to compare the mean difference between the two methods at various triglyceride level, determine the reliable and acceptable values of calculated LDL-c compared with the allowable total error (TEa), which is the medically acceptable less than 10 % or 7.73 mg/dL

Results        : The plasma LDL-c values between the direct measurement and calculated values from the Friedewald, Anandaraja, Puavilai, Chen and Vujovic formulas were highly correlated once the triglyceride is less than or equal to 400 mg/dL. The correlation coefficient are as follow ; 0.983, 0.929, 0.985, 0.982 and 0.985 accordingly. The higher triglyceride levels more than 400 mg/dL, however the correlation decreases. At a different concentration of triglyceride 0-100, 101-200, 201-300  and 301-400 mg/dL show a significantly mean difference of LDL-c from the direct measure and the calculation of five formulas (p<0.001), except at the level 301-400 mg/dL the Chen formula is not different from the direct calculation (p=0.165) whereas  the Vujovic provides the least mean difference to the direct one or the highest accuracy  when triglyceride level at 0-300 mg/dL (mean difference = 2.5, 2.0 and 1.0). The number of samples calculated with Vujovic’s formula is within TEa which reliable and acceptable 93.0%, the latters are Puavilai(87.4%), Chen(67.4%), Friedewald(67.1%) and Anandaraja(60.6%).

Conclusions : The plasma LDL-c values between the direct measurement and calculated values from the Friedewald, Anandaraja, Puavilai, Chen and Vujovic formulas were highly correlation. The LDL-c value calculated from Vujovic’s formula is accurate and the most suitable.

Keywords    : Low density lipoprotein cholesterol, direct LDL-c, calculated LDL-c