Does Fredrickson Friedewald’s formula and direct assay of LDL concentration in serum give varying results? - A pilot retrospective study in a tertiary care hospital

Abstract

Background and Aims: The LDL-C levels guide the cardiovascular risk assessment under the National Cholesterol Education Program Adult Treatment Panel (NCEP) as well as used for the management of dyslipidemia. Traditionally, LDL-C level is calculated using the Friedewald formula i.e., cLDL, however, recently many of the laboratories have shifted to newer methods of direct LDL-C estimation, i.e., dLDL. With this transition, there is increased demand to compare and establish updated LDL-C level cutoffs for the risk assessments of cardiovascular events. Methods: A retrospective observational study, comprising 216 study participants, was conducted in the Department of Biochemistry, Lady Hardinge Medical College, and associated hospitals, in New Delhi for 12 months. Data was collected from 216 adult patients (> 18 years) whose routine fasting lipid profile was done and documented in our clinical biochemistry lab. LDL-C levels done by direct method and calculated methods were compared using the Intraclass correlation coefficient (ICC). Appropriate statistical tests were used with a p-value <0.05 taken as statistically significant. Results: When compared between dLDL-C and cLDL-C significant difference was seen with mean values as 104 ±38.8 and 85.5 ±35.6 mg/dl respectively. However, a strong positive correlation was seen between dLDL-C and cLDL-C, r≤0.9, p<0.01. The ICC showed good reliability for overall comparison between dLDL-C and cLDL-C, however, reliability was found to be poor for group 2. Conclusions: Friedewald and modified Friedewald equations can be used as a substitute for direct homogenous LDL estimation when resources are scarce.

References

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