Table 1.

Comparison of methods for direct LDL-C assay and estimated equations for LDL-C with a reference method

Group	Variable	Ultracentrifugation*	dLDL-C	Friedewald	Martin–Hopkins	Sampson
Group 1 (TG≥400 mg/dL)	Median (IQR)	148 (116–177)	149 (130–170)	85 (59–112)	121 (101–142)	101 (81–122)
	P		0.7745	<0.0001	<0.0001	<0.0001
	Bias (%)		0.5	−42.4	−18.5	−31.7
Group 1a (TG=400–500 mg/dL)	Median (IQR)	151 (115–180)	149 (122–174)	93 (61–124)	126 (101–151)	106 (78–132)
	P		0.4070	<0.0001	<0.0001	<0.0001
	Bias (%)		−1.5	−38.4	−16.6	−30.1
Group 1b (TG=500–900 mg/dL)	Median (IQR)	148 (124–174)	148 (132–165)	77 (55–98)	114 (102–134)	98 (82–112)
	P		0.8201	<0.0001	<0.0001	<0.0001
	Bias (%)		−0.2	−48.3	−22.7	−34.0
Group 2 (LDL-C≤70 mg/dL)	Median (IQR)	58 (49–62)	61 (54–68)	41 (34–46)	45 (37–50)	43 (36–48)
	P		<0.0001	<0.0001	<0.0001	<0.0001
	Bias (%)		5.3	−29.6	−22.9	−25.4
Group 2a (LDL-C=10–40 mg/dL)	Median (IQR)	49 (44–54)	55 (51–63)	34 (29–38)	36 (30–41)	36 (29–40)
	P		<0.0001	<0.0001	<0.0001	<0.0001
	Bias (%)		10.9	−31.8	−25.8	−26.7
Group 2b (LDL-C=40–70 mg/dL)	Median (IQR)	62 (58–66)	65 (61–69)	46 (43–49)	49 (46–53)	48 (45–51)
	P		<0.0001	<0.0001	<0.0001	<0.0001
	Bias (%)		5.8	−25.1	−20.2	−21.9

*Reference method.

Abbreviations: IQR, interquartile range; TG, triglycerides; LDL-C, low-density-lipoprotein cholesterol; dLDL-C, direct LDL-C assay.