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.