Correlation of LDL Cholesterol Calculated by Friedewald’s, Puavilai’s, Vujovic’s, de Cordova’s and Martin’s Formulae with Directly Measured LDL Cholesterol: A Cross-sectional Study

Abstract

Introduction: Measurement of Low Density Lipoprotein Cholesterol (LDL-C) carries high importance in the management of Cardiovascular Disease (CVD). Direct LDL-C measurement is preferred method but this is expensive and inconvenient for the routine laboratories. To date, various types of formulae have been introduced. However, accurate estimation of LDL-C by formula is a challenge. Aim: To determine that which of these calculated formulae (Friedewald’s, Puavilai’s, Vujovic’s, de Cordova’s and Martin’s formulae) show maximum correlation with directly measured LDL-C at different serum triglyceride levels. Materials and Methods: The present cross-sectional study was conducted in the Department of Biochemistry, KLE Centenary Charitable Hospital and Medical Research Centre, Belgaum, Karnataka, India, from December 2020 to December 2021. A total of 280 outpatient fasting complete lipid profiles of patients, aged between 18-50 years were included in the study. LDL-C measured by Friedewald’s formula, Puavilai’s formula, Vujovic’s formula, de Cordova’s formula and Martin’s formula were compared with directly measured LDL-C. Comparison of calculated LDL-C with directly measured LDL-C was done at following Triglyceride (TG) ranges as group 1: <200 mg/dL, group 2: 200-300 mg/dL, group 3: 300-400 mg/dL and group 4: >400 mg/dL. Data analysis was done using Pearson’s correlation coefficient and two paired t-test. Results: Of total 280 samples, 124 participants were in group 1, 91 participants in group 2, 36 participants in group 3 and 29 participants in group 4, and there were 130 males and 150 females. The mean age in group 1, 2, 3 and 4 was 40.9±8.0 years, 38.8±9.2 years, 39.1±10.0 years and 39.8±8.2 years, respectively. Martin’s formula showed maximum correlation with r-value of 0.9979 compared to Friedewald’s, Puavilai’s formula, Vujovic’s formula and de Cordova’s formula. The mean difference was least for Martin’s formula 0.31±3.53 compared to other formulas. Percentage of error was least for Martin’s formula (0.23%) in total study sample and in all groups. Martin’s LDL-C shows highest concordance (90.90%) compared to Frielwald’s (79.60%), Puavilai’s (86.00%), Vujovic’s (83.88%) and de Cordova’s formula (82.76%). Conclusion: In the present study, Martin’s formula showed highest correlation, least mean difference, highest concordance and low percentage of errors in all the groups compared to Frieldwald’s formula, Puavilai’s formula, Vujovic’s formula and de Cordova’s formula.