Assessing the clinical implications of low-density lipoprotein cholesterol equations using Nigerian data.

Abstract

Background: Newer equations, which are more accurate than the Friedewald formula (FF), have been published for the calculation of low-density lipoprotein (LDL) cholesterol. The impact of their adoption on decision-making has not been examined in Nigerian laboratories.

Objective: This study examined the clinical implications of differences in estimating LDL cholesterol by the FF, Martin-Hopkins (MH), and Sampson-National Institutes of Health (NIH) equations.

Methods: Between 01 January 2019 and 31 December 2023, lipid profile data, and the associated gender, were retrieved from the laboratory information system of Synlab Nigeria for persons aged 18-75 years. Differences in LDL cholesterol estimates from the three equations, and agreement with category assignments that determine clinical decisions, were examined.

Results: Lipid profile data from 19 126 records were retrieved. This included data from 8234 (43.1%) women. The difference between FF estimates of LDL cholesterol and the other two equations was less than 10% for over 96% of the data. This difference increased with triglyceride levels. There was at least substantial agreement in the clinical category assignment of the equations, (ĸ > 0.715, p < 0.001). However, when triglycerides were > 1.69 mmol/L, the FF classification of < 1.81 mmol/L was classified as > 1.81 mmol/L in 43.3% and 25.1% of cases by MH and Sampson-NIH, respectively. For triglycerides > 4.51 mmol/L, there was constant bias, with MH higher than Sampson-NIH.

Conclusion: Using the FF formula may significantly impact primary prevention of atherosclerotic cardiovascular disease. Switching to the MH or Sampson-NIH equation is advisable.

What this study adds: This study provides a basis for Nigerian laboratories to switch from the Friedewald formula to one of the newer equations for the calculation of LDL cholesterol.