ORIGINAL: Plasma Low-Density Lipoprotein Cholesterol Estimated by Friedewald Compared to Martin-Hopkins Equation in Nigerian Population

West Afr J Med. 2021 Mar 22; 38(3):255-261. PMID: 33765588

Abstract

Background: Friedewald equation for estimation of plasma low-density lipoprotein cholesterol (LDL-C) has recently been the subject of controversies. We investigated the agreement between LDL-C calculated with the Friedewald equation (LDLC F) and novel Martin-Hopkins formula (LDL-CMH), and the influence of sex, age, and triglyceride stratification on the level of biases.

Methods: We used convenience sample of data from records of 7151 adults who underwent test for plasma lipid profile from 2014 to 2017 at a tertiary Hospital in Nigeria. During the period automated standard enzymatic methods were used for determination of plasma lipids. The Bland-Altman plot was used to evaluate the agreement between the two equations.

Results: Participants were 2953 males and 4198 females. The age of the subjects ranged from 21 to 91 years with overall mean age of 54.2±12.1 years. The discrepancy between LDLC MH and LDL-CF ranged from -0.05 to 0.93 mmol/L (median = 0.16) with a mean value of 0.172 ±0.094 mmol/L. The BlandAltman analysis showed an estimated bias of 6.38% (95% CI = -5.02, 20.0). The bias in males and females was 8.3% (95% CI = -5.6, 22.2) and 6.9% (95% CI = -4.4, 18.3), respectively. At an average LDL-C less than 1.81 mmol/L, estimated bias became increased to 16.6% (95% CI = -6.1, 39.2). The calculated LDL-C MH were significantly higher than LDL-CF irrespective of the level of triglyceride.

Conclusion: Although both showed excellent reliability, the Friedewald equation resulted in a clinically lower LDL-C than the Martin-Hopkins formula. It may be necessary to pay attention to biological sex differences.