Comparison of 2 homogeneous high-density lipoprotein cholesterol assays.

BACKGROUND

High-density lipoprotein cholesterol (HDL-C) is an independent inverse risk factor for coronary artery disease. Current methodologies for measurement of HDL-C in most clinical laboratories involve chemical precipitation-based methods. However, these methods are time-consuming, affected by high triglycerides, are not suitable for complete automation, and require a large sample size. New direct homogeneous methods are now available that do not have these constraints.

DESIGN

We evaluated the performance of 2 direct homogeneous methods, Liquid N-geneous HDL-C assay (LN-HDL) and Boehringer Mannheim HDL Cholesterol assay (BM-HDL), and compared these methods against a modified Centers for Disease Control and Prevention reference method (MR-HDL) in 126 patients with normotriglyceridemia (triglycerides < 4.5 mmol/L, range 0.6-4.3 mmol/ L) and 50 patients with hypertriglyceridemia (triglycerides > or =4.5 mmol/L, range 4.5-18.8 mmol/L).

RESULTS

Excellent precision profiles were exhibited by both homogeneous methods. Both LN-HDL and BM-HDL correlated well with MR-HDL in normotriglyceridemia (r = 0.98, slope = 0.93 and r = 0.97, slope = 1.0, respectively). However, compared with the modified reference method, the LN-HDL correlated better than the BM-HDL in hypertriglyceridemic samples (r = 0.97, slope = 1.0 and r = 0.91, slope = 0.9, respectively). The 1998 National Cholesterol Education Program guidelines for accuracy (bias < +/-5%) were met by LN-HDL in both normotriglyceridemic and hypertriglyceridemic samples (bias = 1.3% and 3.3%, respectively); however, BM-HDL failed to meet the National Cholesterol Education Program accuracy criteria in both triglyceride subgroups (bias = 8.2% and 11.3%, respectively). In addition, the total error for LN-HDL in both normotriglyceridemia (6.6%) and hypertriglyceridemia (8.6%) was well within the National Cholesterol Education Program guidelines for total error (< or =13%); BM-HDL exhibited a higher total error than LN-HDL in normotriglyceridemia (11.9%) and failed to meet the National Cholesterol Education Program guidelines in hypertriglyceridemia (15.0%).

CONCLUSION

Although both homogeneous methods are precise, the LN-HDL assay is superior in accuracy to the BM-HDL assay when compared with the modified reference method.