Cardiovascular disease (CVD) is a group of health conditions affecting the heart and vascular system with very high prevalence and mortality rates. The presence of CVD is characterised by high levels of inflammation which have previously been associated with increased plasma concentrations of N-acetyl neuraminic acid (Neu5Ac). While Neu5Ac has been studied in the context of CVD, Neu5,9Ac₂ has not, despite being the second most abundant sialic acid in human plasma. A small-scale pilot study of thirty plasma samples from patients with diagnosed CVD, and thirty age and sex-matched healthy controls, was designed to gain insight into sialic acids as biomarkers for CVD and potential future areas of study. Each sample was assayed for Neu5Ac and Neu5,9Ac₂ concentrations. Mean Neu5Ac and Neu5,9Ac₂ concentrations were significantly elevated in patients with CVD compared to healthy controls (Neu5Ac: P < 0.001; Neu5,9Ac₂: P < 0.04). Receiver operator curve (ROC) analysis indicated that both Neu5Ac and Neu5,9Ac₂ have reasonable predictive power for the presence of CVD (Neu5Ac AUC: 0.86; Neu5,9Ac₂ AUC: 0.71). However, while Neu5Ac had both good sensitivity (0.82) and specificity (0.81), Neu5,9Ac₂ had equivalent specificity (0.81) but very poor sensitivity (0.44). A combination marker of Neu5Ac + Neu5,9Ac₂ showed improvement over Neu5Ac alone in terms of predictive power (AUC: 0.93), sensitivity (0.87), and specificity (0.90). Comparison to a known inflammatory marker, high sensitivity c-reactive protein (hs-CRP: P-value: NS, ROC:0.50) was carried out, showing that both Neu5Ac and Neu5,9Ac₂ outperformed this marker. Further to this, hs-CRP values were combined with the three different sialic acid markers to determine any effect on the AUC values. A slight improvement in AUC was noted for each of the combinations, with Neu5Ac + Neu5,9Ac₂ + hs-CRP giving the best AUC of 0.97 overall. Thus, Neu5Ac would appear to offer good potential as a predictive marker for the presence of CVD, which the addition of Neu5,9Ac₂ predictive power improves, with further improvement seen by the addition of hs-CRP.

心血管疾病（CVD）是一组影响心脏和血管系统的健康状况，患病率和死亡率非常高。CVD 的存在以高水平炎症为特征，此前认为这种炎症与N-乙酰神经氨酸 (Neu5Ac) 血浆浓度升高有关。虽然 Neu5Ac 已在 CVD 背景下进行了研究，但 Neu5,9Ac ₂尚未在人血浆中含量第二丰富的唾液酸中进行研究。一项小规模试点研究对来自 CVD 诊断患者的 30 份血浆样本和 30 名年龄和性别匹配的健康对照进行了研究，旨在深入了解唾液酸作为 CVD 生物标志物和未来潜在的研究领域。测定每个样品的Neu5Ac和Neu5,9Ac ₂浓度。与健康对照相比，CVD 患者的平均 Neu5Ac 和 Neu5,9Ac _{2浓度显着升高（Neu5Ac：P < 0.001；Neu5,9Ac 2}：P < 0.04）。受试者工作曲线（ROC）分析表明，Neu5Ac 和 Neu5,9Ac ₂对 CVD 的存在具有合理的预测能力（Neu5Ac AUC：0.86；Neu5,9Ac ₂ AUC：0.71）。然而，虽然Neu5Ac 具有良好的敏感性(0.82) 和特异性(0.81)，但Neu5,9Ac ₂具有相同的特异性(0.81)，但敏感性非常差(0.44)。_{Neu5Ac + Neu5,9Ac 2}组合标记物在预测能力 (AUC: 0.93)、敏感性 (0.87) 和特异性 (0.90) 方面比单独使用 Neu5Ac 有所改善。与已知炎症标志物高灵敏度 C 反应蛋白（hs-CRP：P 值：NS，ROC：0.50）进行比较，结果表明 Neu5Ac 和 Neu5,9Ac ₂均优于该标志物。此外，将 hs-CRP 值与三种不同的唾液酸标记物相结合，以确定对 AUC 值的影响。每种组合的 AUC 均略有改善，其中 Neu5Ac + Neu5,9Ac ₂  + hs-CRP 的总体 AUC 最佳，为 0.97。因此，Neu5Ac 似乎具有作为 CVD 存在的预测标记的良好潜力，添加 Neu5,9Ac ₂可以提高预测能力，添加 hs-CRP 可以进一步提高预测能力。