Prognostic utility of NT-proBNP in acute exacerbations of chronic pulmonary diseases

Abstract

Background The prognostic value of NT-proBNP levels in patients admitted to hospital due to acute exacerbations of chronic pulmonary diseases (CPDs) is unknown. Setting Internal Medicine units at two general hospitals. Methods NT-proBNP levels were obtained within 72 h after admission in 192 consecutive patients with acute exacerbations of CPDs and no history of heart failure or diuretic treatment. Clinical characteristics and main outcomes were assessed over a 12-month follow-up. NT-proBNP cut-points for outcomes were obtained by ROC (receiver operating characteristics) curve analysis. Results Chronic obstructive lung disease (69.3%) and chronic asthma (22.4%) were the most prevalent CPDs, and non-pneumonic acute respiratory infection (72.4%) and pneumonia (22.9%) were the most frequent causes of exacerbation. Atrial flutter or fibrillation rate was 11%. During the one-year follow-up period, 22 patients died, 42 were re-admitted, 46 received new long-term oxygen therapy, and 39 received new diuretic treatment. NT-proBNP values correlated with hospitalisation days. NT-proBNP values over 587.9 pg/ml were associated with significantly raised one-year mortality (OR = 3.90; 95% IC 1.46–10.47; p = 0.006) and over 782.2 pg/ml with cardio-pulmonary deaths (OR = 6.38; 95% IC 1.91–21.3; p = 0.002). That association persisted after adjustment for age, gender, creatinine levels and cardiac rhythm. NT-proBNP values over 628.7 pg/ml were associated with significantly higher probability of new diuretic treatment (OR = 4.38; IC 95% 2.07–9.25; p < 0.001). The negative predictive values for these cut-points ranged from 89% to 97%. Conclusion NT-proBNP levels below 587.9 pg/ml in patients with acute exacerbations of CPD were associated with favourable one-year outcomes.