Department of Medicine, Sahlgrenska University Hospital, Sahlgrenska Academy, University of Gothenburg, 413 45 Gothenburg, Sweden.
Int J Cardiol. 2012 Feb 23;155(1):1-5. doi: 10.1016/j.ijcard.2011.01.083. Epub 2011 Feb 18.
Plasma BNP and NT-proBNP are often used as interchangeable parameters in heart failure care in clinical practice. In our previous study we have shown that inflammation was able to induce increased NT pro BNP in a hospital cohort with chronic heart failure in the elderly, indicating that NT-proBNP/BNP ratio should be evaluated concomitantly with inflammatory status to avoid overestimation of heart failure severity. The present study was aimed to evaluate the clinical significance of NT-proBNP/BNP ratio in comparison with NTpro BNP or BNP alone as a prognostic indicator in a 2-year follow up of elderly heart failure population.
One hundred and eight-nine elderly heart failure patients (72 ± 11 years, male 52%, LVEF 46 ± 14%) were enrolled consecutively during 2006 and 2007 and followed up during 2 years. NTpro BNP and BNP were measured routinely.
We have found that NTpro BNP/BNP ratio provides no additional prognostic information during follow up as compared to NTpro BNP or BNP alone in an elderly population with chronic heart failure. By the use of ROC curves, for total mortality predictive accuracy during 2 years, the cut-off values are NTproBNP ≥ 800 pg/ml, BNP > 60 pg/ml and NTpro BNP/BNP ratio>6.4 respectively. In terms of NTpro BNP, as long as its serum level is above 2000 pg/ml it indicates poor prognosis. However there is an overlap between serum concentration range 2000-8000 pg/ml and >8000 pg/ml in terms of prognostic indicator. Similarly for BNP, as long as its serum level is above 100 pg/ml, it indicates poor prognosis. However there is an overlap between serum concentration range 100-800 pg/ml and >800 pg/ml in terms of prognostic indicator. There was significant correlation between survival and NTpro BNP, BNP and Cystatin-C but not with NTpro BNP/BNP ratio. Such correlation exists irrespective of subgroups regardless of less than or older than 70 years old.
Our results demonstrated that in elderly heart failure population NTpro BNP/BNP ratio may provide diagnostic help in the presence of acute infection but no additional prognostic information in the long run as compared with NTpro BNP or BNP alone. Furthermore, both NTpro BNP and BNP are useful prognostic biomarkers indeed but they need to be interpreted with caution when it is used as a single biomarker and in the meantime concomitant diseases exist because patients may die due to non-cardiac causes.
在临床实践中，BNP 和 NT-proBNP 常被用作心力衰竭治疗中可互换的参数。在我们之前的研究中，我们已经表明炎症能够在患有慢性心力衰竭的老年住院患者中诱导 NT-proBNP 的增加，这表明 NT-proBNP/BNP 比值应该与炎症状态同时评估，以避免对心力衰竭严重程度的过度估计。本研究旨在评估 NT-proBNP/BNP 比值作为预后指标的临床意义，并与 NT-proBNP 或 BNP 单独进行比较，以评估老年心力衰竭患者的 2 年随访结果。
我们连续纳入了 2006 年至 2007 年期间的 189 名老年心力衰竭患者（72 ± 11 岁，男性占 52%，LVEF 为 46 ± 14%），并进行了 2 年的随访。常规检测 NT-proBNP 和 BNP。
我们发现，在患有慢性心力衰竭的老年人群中，与 NT-proBNP 或 BNP 单独相比，NT-proBNP/BNP 比值在随访期间并未提供额外的预后信息。通过使用 ROC 曲线，对于 2 年总死亡率的预测准确性，截值分别为 NT-proBNP≥800pg/ml、BNP>60pg/ml 和 NT-proBNP/BNP 比值>6.4。就 NT-proBNP 而言，只要其血清水平高于 2000pg/ml，就预示着预后不良。然而，在预后指标方面，血清浓度范围在 2000-8000pg/ml 和>8000pg/ml 之间存在重叠。同样，对于 BNP，只要其血清水平高于 100pg/ml，就预示着预后不良。然而，在预后指标方面，血清浓度范围在 100-800pg/ml 和>800pg/ml 之间也存在重叠。存活与 NT-proBNP、BNP 和胱抑素 C 之间存在显著相关性，但与 NT-proBNP/BNP 比值无关。这种相关性存在于所有亚组中，无论年龄是否小于或大于 70 岁。
我们的结果表明，在老年心力衰竭患者中，与 NT-proBNP 或 BNP 单独相比，NT-proBNP/BNP 比值在急性感染时可能提供诊断帮助，但在长期随访中没有提供额外的预后信息。此外，NT-proBNP 和 BNP 确实是有用的预后生物标志物，但当它们被用作单一生物标志物时，需要谨慎解释，同时存在伴随疾病，因为患者可能因非心脏原因而死亡。
