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

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.

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.

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.

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.

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

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.