Accuracy and precision of blood lipid measurements using the Cholestech LDX lipid analyzer

The Cholestech L.D.X® System is a relatively new portable analyzer which has the capability of performing a lipid profile from venous whole blood, venous serum, or capillary blood in about four minutes. The purpose of this study was to determine the accuracy and precision of the Cholestech L.D.X®, with specific comparisons between two instruments and two technicians. Forty volunteers with a wide range of cholesterol values gave two finger capillary samples (FS) and one venous blood sample (VEN). Both sample types were analyzed in duplicate by each technician on 2 different L.D.X® analyzers. A laboratory with a link to the National Reference System for Cholesterol Measurement (REF) was used as the standard for accuracy comparisons. Manufacturer's controls were used to assess within-day precision and two human serum samples with values ≈ 200 and 240 mg.dl-1 total cholesterol (TC) were used for day-to-day precision determinations. Both samples were analyzed by each technician on each instrument ten times for within-day precision (W-D). The samples were frozen, thawed, and analyzed twice by each technician on ten different days for day-to-day precision (D-D). The % coefficient of variation (CV) ranges for day-to-day precision of TC, TRG, and HDL measurements were 4.2-5.7, 4.4-8.1, and 5.0-7.0 respectively. The % CV ranges for within-day precision of TC, TRG, and HDL measurements were 1.4-4.1, 4.6-5.8, and 3.5-5.6 respectively. The mean % bias of TC, TRG, and HDL measurements were 3.5, 8.0, and 6.6 respectively. ANOVA procedures revealed no significant differences between technicians or analyzers, and no significant differences among the FS, VEN, or REF measures for any of the analytes. In conclusion, the L.D.X® analyzer is capable of meeting the National Cholesterol Education Program's recommendations for accuracy and precision of TC measurement for portable cholesterol analyzers.