Prognostic Role of NT-proBNP for in-Hospital and 1-Year Mortality in Patients with Acute Exacerbations of COPD

Background and objective: The association between N-terminal pro B-type natriuretic peptide (NT-proBNP) concentrations and in-hospital and 1-year mortality in acute exacerbations of chronic obstructive pulmonary disease (AECOPD) patients is largely unknown. Our objective was to explore the usefulness of NT-proBNP concentrations in AECOPD patients as a prognostic marker for in-hospital and 1-year mortality. Methods: NT-proBNP levels were measured in patients upon admission and laboratory and clinical data were also recorded. The cut-point for the NT-proBNP concentration level for in-hospital death was obtained using the receiver operating characteristic (ROC) curve. Univariate and multivariate logistic regression and Cox regression were used in the analyses of factors of in-hospital and 1-year mortality. Results: A total of 429 patients were enrolled. Twenty-nine patients died during hospitalization and 59 patients died during the 1-year follow-up. Patients who died in-hospital compared with those in-hospital survivors were older (80.14 +/- 6.56 vs 75.93 +/- 9.45 years, p=0.003), had a higher percentage of congestive heart failure (65.52% vs 33.75%, p<0.001), had higher NT-proBNP levels (5767.00 (1372.50-12,887.00) vs 236.25 (80.03-1074.75) ng/L, p<0.001), higher neutrophil counts (10.52 +/- 5.82 vs 7.70 +/- 4.31, p=0.016), higher D-dimer levels (1231.62 +/- 1921.29 vs 490.11 +/- 830.19, p=0.048), higher blood urea nitrogen levels (9.91 +/- 6.33 vs 6.51 +/- 4.01 mmol/L, p=0.001), a lower body mass index (19.49 +/- 3.57 vs 22.19 +/- 4.76, p=0.003), and higher hemoglobin levels (122.34 +/- 25.36 vs 130.57 +/- 19.63, p=0.034). The area under the ROC curve (AUC) for NT-proBNP concentration was 0.88 (95% confidence interval [CI], 0.84-0.93). NT-proBNP concentrations >= 551.35 ng/L were an independent prognostic factor for both in-hospital and 1-year mortality after adjustment for relative risk (RR) (RR=29.54, 95% CI 3.04-286.63, p=0.004 for the multivariate logistic regression analysis) and hazard ratio (HR) (HR=4.47, 95% CI, 2.38-8.41, p<0.001 for the multivariate cox regression analysis). Conclusion: NT-proBNP was a strong and independent predictor of in-hospital and 1-year mortality in AECOPD patients.