Objective: Whether vitamin B6 exerts an independent or a synergic effect in combination with inflammation for the risk of coronary artery disease (CAD) is unclear. The purpose of this study was to investigate whether plasma pyridoxal 5'-phosphate (PLP) is dependent on or independent of the inflammation marker C-reactive protein (CRP) to associate with the risk of CAD.
Methods: This was a hospital-based case-control. Patients were identified with cardiac catheterization as having at least 70% stenosis of one major coronary artery were assigned to the case group (n = 184). The control group (n = 516) was comprised of healthy individuals with normal blood biochemical values. All subjects' height, weight, blood pressure, plasma PLP, homocysteine, high-sensitivity CRP (hs-CRP), and lipid profiles were measured.
Results: Plasma PLP concentration was only negatively associated with hs-CRP level in the control group (beta = -0.001, P = 0.03) but not in the CAD or pooled groups. The magnitude of the risk of CAD for low plasma PLP (odds ratio [OR] 2.39) and high hs-CRP (OR 3.37) was very similar. Low plasma PLP concentration combined with low hs-CRP level (OR 2.34) and high plasma PLP concentration combined with high hs-CRP level (OR 3.61) were independently associated with risk for CAD. However, the combined presence of low PLP and higher hs-CRP levels enhanced the risk of CAD and the magnitude was substantially greater (OR 4.35).
Conclusion: Plasma PLP and hs-CRP are independently associated with an increased risk of CAD, the combined presence of low PLP and high hs-CRP enhanced the risk of CAD, and the magnitude was almost double.