Factors to consider with estimated low-density lipoprotein cholesterol using the new Sampson/NIH equation.

INTRODUCTION:The most commonly utilized method for determining low-density lipoprotein cholesterol (LDLc) is by Friedewald estimation (FeLDLc). A new approach to better estimate LDLc has been proposed by Sampson et al. 2020, known as the Sampson/National Institutes of Health (NIH) estimation of LDLc (NeLDLc), to overcome the limitations of FeLDLc. Non-high-density lipoprotein-cholesterol (Non-HDLc), has equivalent cut-offs to LDLc, established by the 2021 Canadian Cardiovascular Society (CCS) guideline. We hypothesized that NeLDLc remains an inadequate substitute at high triglyceride levels when compared to Non-HDLc. METHODS:A retrospective analysis of 120,959 lipid profiles (47085 patients) spanning five years across a large academic medical center was utilized for comparison of NeLDLc and FeLDLc relative to Non-HDLc as a function of triglyceride content. Regression and concordance between calculated methods were determined at various triglyceride levels to determine optimal utilization of NeLDLc. RESULTS:NeLDLc is generally more correlated and has greater concordance than FeLDLc with Non-HDLc. NeLDLc with increasing triglycerides can produce negatively erroneous results, even with triglycerides < 4.52 mmol/L (400 mg/dL). The largest variation of NeLDLc results is notable at < 0.5 mmol/L (19 mg/dL). Currently, the 2021 CCS guideline recommends reliance on Non-HDLc when triglycerides are > 1.5 mmol/L (133 mg/dL). With the use of NeLDLc, this triglyceride cut-off can be increased to 1.7 mmol/L(150 mg/dL), making it consistent with the hypertriglyceridemia flagging limit. CONCLUSION:NeLDLc offers increased concordance and correlation to Non-HDLc when compared to FeLDLc. However, caution is warranted when triglycerides are > 4.5 mmol/L and when NeLDLc results are < 0.5 mmol/L. Adopting NeLDLc enables flagging at 1.7 mmol/L (vs. 1.5 mmol/L) of triglycerides to suggest reliance on Non-HDLc while simultaneoulsly indicating hypertriglyceridemia.