A Novel LDLC Equation is Superior to the NIH LDLC Equation and the Friedewald Equation

Figures & data

Table 1 The Characteristics of Establishment of the LDLC Equation Group

Index	Establishment of the LDLC Equation Group
	TG≤1.7 mmol/L	TG>1.7 mmol/L
n	16,143	7083
Age	51(35–65)	54(40–65)
TG	1.05(0.80–1.33)	2.30(1.95–2.97)
TC	4.58(4.00–5.22)	5.13(4.52–5.82)
nonHDLC	3.24(2.67–3.80)	3.96(3.42–4.57)
LDLC	2.97(2.51–3.46)	3.42(2.95–3.94)
LDL_F	2.74(2.23–3.28)	2.77(2.19–3.36)
LDL_NIH	2.82(2.27–3.40)	3.09(2.50–3.71)

Table 2 Instrument Performance Parameters (TG, TC, HDL-C, and LDL-C) of AU5821 Chemistry Analyzer

Analytes	Trueness	Precision	Reportable Range
TC	NCCL EQA |bias|≤4.5%	Repetitive precision: CV ≤2.25% Intermediate precision: CV ≤3.00%	Linearity range: 0.5–18.0 mmol/L; Clinical reportable range: 0.5–36.0 mmol/L.
HDL-C	NCCL EQA |bias|≤15.0%	Repetitive precision: CV ≤7.50% Intermediate precision: CV ≤10.00%	Linearity range: 0.05–4.65 mmol/L; Clinical reportable range: 0.05–9.30 mmol/L.
LDL-C	NCCL EQA |bias|≤15.0%	Repetitive precision: CV ≤7.50% Intermediate precision: CV ≤10.00%	Linearity range: 0.26–10.30; Clinical reportable range: 0.26–20.60 mmol/L.
TG	NCCL EQA |bias|≤7.0%	Repetitive precision: CV ≤3.50% Intermediate precision: CV ≤4.67%	Linearity range: 0.1–11.3 mmol/L; Clinical reportable range: 0.1–45.2 mmol/L.

Abbreviations: TC, total cholesterol; HDL-C, high-density lipoprotein cholesterol; LDL-C, low-density lipoprotein cholesterol; TG, triglycerides.

Figure 1 The characteristics of the participants included in the construction of the novel LDLC equations.

Abbreviations: TC, total cholesterol; HDL, high-density lipoprotein cholesterol; LDL, low-density lipoprotein cholesterol; TG, triglycerides, in mmol/L.

Figure 2 We obtained two novel LDLC equations.

Abbreviations: Direct_LDLC and LDL-C (direct clearance method) were tested with an AU5800 Modular System (Beckman Coulter, Inc., America). TC, total cholesterol; HDL, high-density lipoprotein cholesterol; NonHDLC=TC-HDL, in mmol/L.

Figure 3 The histogram of the characteristics of the unselected patient cohort.

Abbreviations: TC, total cholesterol; HDL, high-density lipoprotein cholesterol; LDL, low-density lipoprotein cholesterol; TG, triglycerides; LDL_F, LDL-C calculated using the Friedewald equation; LDL_NIH, LDL-C calculated using the NIH equation; LDL_nonHDLC-equation=−0.899+1.195*nonHDLC-0.00347*nonHDLC² and LDL_TC-equation=−2.775+1.29*TC-0.00990*TC², in mmol/L.

Figure 4 Scatter plots for the direct low-density lipoprotein cholesterol (LDLC) and LDLC equations. Their relationship was analysed using Spearman’s approach.

Abbreviations: LDL (direct clearance method) was tested with an AU5800 Modular System (Beckman Coulter, Inc., America); LDL_F, LDL-C calculated using the Friedewald equation; LDL_NIH, LDL-C calculated using the NIH equation; LDL_nonHDLC-equation=−0.899+1.195*nonHDLC-0.00347*nonHDLC² and LDL_TC-equation=−2.775+1.29*TC-0.00990*TC², in mmol/L.

Figure 5 Receiver operating characteristic curves of the LDLC equations for predicting direct low-density lipoprotein cholesterol (direct LDLC levels are >1.55 mmol/L, >1.80 mmol/L, >2.60 mmol/L, >3.36 mmol/L, >4.12 mmol/L, and >4.90 mmol/L).

Abbreviations: LDL (direct clearance method) was tested with an AU5800 Modular System (Beckman Coulter, Inc., America); LDL_F, LDL-C calculated using the Friedewald equation; LDL_NIH, LDL-C calculated using the NIH equation; LDL_nonHDLC-equation=−0.899+1.195*nonHDLC-0.00347*nonHDLC² and LDL_TC-equation=−2.775+1.29*TC-0.00990*TC², in mmol/L.

Figure 6 Bland‒Altman plot of LDLC from four LDLC equations.

Abbreviations: LDL (direct clearance method) was tested with an AU5800 Modular System (Beckman Coulter, Inc., America); LDL_F, LDL-C calculated using the Friedewald equation; LDL_NIH, LDL-C calculated using the NIH equation; LDL_nonHDLC-equation=−0.899+1.195*nonHDLC-0.00347*nonHDLC² and LDL_TC-equation=−2.775+1.29*TC-0.00990*TC², in mmol.