Comparison common equations for LDL-C calculation with direct assay and developing a novel formula in Iranian children and adolescents: the CASPIAN V study

BACKGROUND: Hypercholesterolemia is a common dyslipidemia that leads to atherosclerosis. It is proved that early stages of atherosclerosis begins in early stages of life. In several studies, widespread prevalence of dyslipidemia in children is reported. So, assessment of lipid profile in children and adolescence is necessary for early diagnosis of dyslipidemia. Laboratory methods for measuring LDL are not available and economical. So, in some laboratories Friedwald method is used to determine LDL level. But, the preciseness of this method is not acceptable. Further, the preciseness of this method was not assayed in children and adolescence. So, it seems that assaying the preciseness of different methods is necessary. METHODS: The methodology of this work is on the basis of findings of the Caspian V study. This study was conducted in 30 provinces of Iran during 2015. The population of this work was rural and urban students aged 7–18 years old. The level of total cholesterol (TC), HDL, LDL, and TG were measured using laboratory methods. The average and variances values were determined for each group of data using SPSS. Further, LDL values were calculated with a new formula introduced in this work. A comparison was made between the new formula and the other methods. RESULTS: In the present study, we found that compare to four common formulas, Friedwald was the best equation to estimate LDL-C concentrations in Iranian children and adolescents and the new formula was the next accurate equation. The strongest correlation between Friedwald and the new equation was found for those with 15–18 years old. CONCLUSION: Considering the cut-off points of TG (100 mg/dL), we observed the strongest correlation between Friedwald equation and direct assay and the weakest one was for Ahmadi formula in subjects with either greater or lower TG concentrations. Furthermore, we found that Anandraja equation had the most sensitivity (89.5%), while the most specificity was dedicated to the new formula (98.9%).