Serum N-Terminal Pro-B-Type Natriuretic Peptide (NT-proBNP) as a Prognostic Biomarker for In-Hospital Mortality in Acute Exacerbation of Chronic Obstructive Pulmonary Disease: A Prospective Observational Study

Abstract

Background: Acute exacerbation of chronic obstructive pulmonary disease (AECOPD) is a major cause of morbidity, hospital admission and mortality worldwide. Cardiovascular comorbidity is highly prevalent in patients with COPD and contributes substantially to inhospital mortality during exacerbations. N-terminal pro-B-type natriuretic peptide (NTproBNP), a quantitative biomarker of myocardial wall stress, has been proposed as a prognostic marker in AECOPD. The present study evaluated the prognostic value of admission serum NT-proBNP for in-hospital mortality in patients hospitalised with AECOPD. Methods: A prospective observational study was conducted over 12 months in a tertiary care medical unit. One hundred and fifty consecutive adults aged 40 years or above with a confirmed diagnosis of COPD admitted with AECOPD were enrolled. Serum NTproBNP was measured at admission, and patients were followed until discharge or inhospital death. The primary outcome was in-hospital mortality. The discriminative performance of NT-proBNP was evaluated using receiver operating characteristic (ROC) curve analysis. Independent predictors of mortality were identified by multivariable logistic regression. Results: In-hospital mortality occurred in 22 of 150 patients (14.7%). The median admission NT-proBNP concentration was significantly higher in non-survivors than in survivors (3,260 [IQR 1,840–5,420] versus 720 [IQR 320–1,460] pg/mL; p < 0.001). The area under the ROC curve for NT-proBNP for the prediction of in-hospital mortality was 0.864 (95% CI 0.781–0.946). At the optimal cut-off of 1,500 pg/mL, NT-proBNP had a sensitivity of 77.3%, specificity of 82.0%, positive predictive value of 42.5% and negative predictive value of 95.5%. In multivariable analysis, NT-proBNP > 1,500 pg/mL was an independent predictor of mortality (adjusted OR 7.8, 95% CI 2.6–23.4; p < 0.001), together with serum albumin and admission GOLD severity stage. Conclusion: Admission serum NT-proBNP is a robust and independent predictor of in-hospital mortality in patients hospitalised with AECOPD. Routine measurement of NT-proBNP at admission may permit early identification of high-risk patients who could benefit from intensified monitoring, integrated cardiac-pulmonary management and earlier escalation of care.