Comparison of Friedewald’s and Anandaraja’s formula with direct estimation of low-density lipoprotein cholesterol in Shivamogga population

Background: Estimation of low density lipoprotein cholesterol (LDL-C) is crucial in management of coronary artery disease patients. There are many homogenous assays currently available for the estimation of serum LDL-C. Most clinical laboratories determine LDL-C (mg/dl) by Friedewald’s formula (FF). Recently Anandaraja and colleagues have derived a new formula for calculating LDL-C. This formula needs to be evaluated before it is extensively applied in diagnosis. Aim: The aim of this study was to compare the results obtained by direct homogenous assay for LDL-C to those obtained by Friedewald’s and Anandaraja’s formulas with the assumption that the results obtained by direct assay are the most accurate. Materials and methods: We measured Lipid profile (TC, TG, HDL-C, D-LDL-C) by direct homogenous method in 715 fasting samples. Simultaneously Friedewald’s and Anandaraja’s formulas were also used for calculation of LDL-C (FF-LDL-C and AR-LDL-C, respectively). Results: The mean LDL-C levels were 117.78 ± 13.797, 115.51 ± 12.854 and 112.93 ± 11.671 mg/dl for D-LDL-C, FF-LDL-C and AR-LDL-C respectively. There was a statistically significant difference between the results (P ? 0.001) obtained by calculation formulas compared to the measured LDL-C. There was underestimation of LDL-C by 2.27 mg/dl and 4.85 mg/dl by Friedewald’s and Anandaraja’s formulas respectively. In this study, the Pearson’s correlation between FF-LDL-C and D-LDL-C was 0.881 and that between AR-LDL-C and D-LDL-C was 0.880. Bland?Altman graphs showed a definite agreement between mean and differences of the calculation formulas and direct LDL-C with 95% of values lying with in ±2 SD limits. Conclusion: The results of our study showed that FF is better in agreement with D-LDL-C than Anandaraja’s formula for estimation of LDL-C by calculation though both lead to its underestimation.