Novel LDL-C Estimation Superior to Standard Method
The novel method for estimating low-density lipoprotein-cholesterol (LDL-CN), which uses a flexible approach to derive patient-specific triglyceride (TG) to LDL-C ratios, performed better with both fasting and non-fasting samples than the standard Friedewald method (LDL-CF), according to a recent study.
In their study, the researchers hypothesized that this flexible novel method would be more accurate than the standard fixed method for estimating LDL-C in patients who did not fast prior to sample collection. They tested their hypothesis using a cross-sectional sample of 1,545,634 patients from the Very Large Database of Lipids study. A total of 959,153 patients completed a short fasting period (less than 10 to 12 hours) and 586,481 patients did not fast before their blood was drawn.
_________________________________________________________________
RELATED CONTENT
Lowering LDL-C Alone Does Not Reduce CV Risk
New Guidelines from AACE/ACE Emphasize LDL-C Targets
_________________________________________________________________
LDL-C content was measured using rapid ultracentrifugation (LDL-CD). The accuracy of LDL-CN and LDL-CF was defined as the percentage of LDL-CD falling within an estimated LDL-C category or by clinical cutpoints. Additionally, TG levels were evaluated among those with low estimated LDL-C. The magnitude of absolute and percent differences between LDL-C and LDL-CD were stratified by LDL-C and TG categories.
Overall, the researchers found that the novel method had a higher accuracy for both fasting and non-fasting sample across all LDL-C categories compared with the Friedewald estimation. Non-fasting LDL-CN had superior accuracy to LDL-CF for samples with LDL-C below 70 mg/dL (92% vs 71%). The difference between LDL-CF and LDL-CD was 10 mg/dL or more among 19% of patients who fasted and 30% of patients who did not fast. Conversely, only 2% of fasting patients and 3% of non-fasting patients had similar differences with the novel estimation.
The accuracy of LDL-C below 70 mg/dL decreased as TG increased, specifically for Friedewald estimations compared with the novel method. LDL-CN below 70 mg/dL accuracy was superior to LDL-CF among non-fasting patients with TG from 200 to 399 mg/dL. Within this TG range, LDL-CF and LCL-CD had a difference of 10 mg/dL or more among 75% of fasting patients and 81% of non-fasting patients. Conversely, only 25% of fasting patients and 20% of non-fasting patients had similar differences with LDL-CN.
“Novel adaptable LDL-C estimation performs better in non-fasting samples than the fixed Friedewald estimation, with a particular accuracy advantage in settings of low LDL-C and high TG,” the researchers concluded. “In addition to stimulating further study, these results may have immediate relevance to guideline committees, laboratory leadership, clinicians and patients.”
—Melissa Weiss
Reference:
Sathiyakumar V, Park J, Golozar A, et al. Fasting vs Non-Fasting and Low-Density Lipoprotein-Cholesterol Accuracy [published online October 16, 2017]. Circulation. https://doi.org/10.1161/CIRCULATIONAHA.117.030677.