This was a single-center, cross-sectional study designed to investigate a novel composite biomarker, the Hemopexin-Apolipoprotein B (Hpx•apoB) product, for its association with coronary artery disease (CAD). The study aimed to determine if the Hpx•apoB product could serve as an independent predictor for the presence and severity of CAD and to evaluate its incremental value in improving risk stratification when added to existing clinical risk models.
The pathophysiology of coronary artery disease (CAD) involves complex interactions between lipid dysregulation and oxidative stress. This study proposed and evaluated a novel composite biomarker, the Hemopexin-Apolipoprotein B (Hpx•apoB) product, which integrates a marker of atherogenic particle burden (apoB) with a marker reflecting the systemic response to heme-induced oxidative stress (Hpx). From January 2019 to December 2023, a total of 460 participants were enrolled: 350 patients with angiographically confirmed CAD (≥50% stenosis in a major coronary artery) and 110 control subjects without significant stenosis. Plasma Hpx was quantified using liquid chromatography-tandem mass spectrometry (LC-MS/MS). The study used multivariate logistic regression to assess the independent association between the Hpx•apoB product and CAD. Furthermore, its incremental diagnostic value was evaluated by calculating the area under the receiver operating characteristic curve (AUC), net reclassification improvement (NRI), and integrated discrimination improvement (IDI) when added to conventional risk factors and established risk scores (Framingham Risk Score and SCORE2).
Study Type
OBSERVATIONAL
Enrollment
460
Standard coronary angiography was performed via the radial or femoral approach on all participants to assess the presence and severity of coronary artery disease. Angiograms were used to determine coronary stenosis, which formed the basis for classifying participants into the CAD group (≥50% stenosis) or the control group (\<50% stenosis).
Fasting blood samples were collected from all participants to measure the novel Hpx•apoB product. Plasma hemopexin (Hpx) was quantified using liquid chromatography-tandem mass spectrometry (LC-MS/MS) and apolipoprotein B (apoB) was measured using standard automated methods. This biomarker was the primary variable of interest for its association with CAD.
Renmin Hospital, Hubei University of Medicine
Shiyan, Hubei, China
Odds Ratio for the Presence of Coronary Artery Disease per Unit Increase in Hpx•apoB Product
This outcome assesses the strength of association between the biomarker and CAD. The plasma concentration of the Hpx•apoB product (Unit: mg²/L²) was used as a continuous variable in a multivariable logistic regression model to predict the presence of CAD. The result is expressed as an Odds Ratio (OR), a unitless measure, with a 95% confidence interval.
Time frame: Baseline
Change in Area Under the Receiver Operating Characteristic Curve (AUC)
This outcome measures the incremental predictive value of the Hpx•apoB product. The AUC of a baseline risk model (containing hs-CRP and LDL-C) was compared to the AUC of the same model with the Hpx•apoB product added. The change in AUC (ΔAUC) quantifies the improvement in model discrimination. AUC is a unitless value ranging from 0.5 to 1.0.
Time frame: Baseline
Comparison of Hpx•apoB Product Concentration by Number of Diseased Vessels
To assess the association with CAD severity, the mean plasma concentration of the Hpx•apoB product (Unit: mg²/L²) was compared across patient groups categorized by the number of diseased coronary vessels (one-, two-, or three-vessel disease), evaluated using a test for trend.
Time frame: Baseline
Correlation Between Hpx•apoB Product and Gensini Score
To assess the association with angiographic severity of CAD, the Spearman correlation coefficient was calculated between the plasma concentration of the Hpx•apoB product (Unit: mg²/L²) and the Gensini score. The Gensini score is a unitless index of atherosclerosis severity.
Time frame: Baseline
Correlation Between Hpx•apoB Product and High-Sensitivity C-Reactive Protein (hs-CRP)
The Spearman correlation coefficient was calculated to assess the relationship between the plasma concentration of the Hpx•apoB product and hs-CRP (Unit: mg/L). The correlation coefficient is a unitless value.
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Time frame: Baseline
Correlation Between Hpx•apoB Product and Low-Density Lipoprotein Cholesterol (LDL-C)
The Spearman correlation coefficient was calculated to assess the relationship between the plasma concentration of the Hpx•apoB product and LDL-C (Unit: mmol/L). The correlation coefficient is a unitless value.
Time frame: Baseline
Correlation Between Hpx•apoB Product and Triglycerides (TG)
The Spearman correlation coefficient was calculated to assess the relationship between the plasma concentration of the Hpx•apoB product and triglycerides (Unit: mmol/L). The correlation coefficient is a unitless value.
Time frame: Baseline
Correlation Between Hpx•apoB Product and Estimated Glomerular Filtration Rate (eGFR)
The Spearman correlation coefficient was calculated to assess the relationship between the plasma concentration of the Hpx•apoB product and eGFR (Unit: mL/min/1.73m²). The correlation coefficient is a unitless value.
Time frame: Baseline