The amino-terminal fragment of pro-brain natriuretic peptide in plasma as a biological marker for predicting mortality in community-acquired pneumonia: a cohort study

Abstract

Abstract Aim: Community-acquired pneumonia (CAP) is an infectious disease that causes the highest mortality rates in developed countries. The primary endpoint of this study was to evaluate the relationship between the plasma concentration of the amino-terminal fragment of pro-brain natriuretic peptide (NT-ProBNP) at the time of CAP diagnosis in a hospital emergency room (HER) and its severity, determined as mortality at 30 days. Materials and Methods: A prospective, observational cohort study was used to determine NT-ProBNP (ng/L) in patients with CAP, with a follow-up over 30 days and analysis of the mortality rate. Results: A total of 338 patients were assessed. Thirty patients died within the first 30 days (10.5%). The mean NT-ProBNP values in the deceased patients were 14,035 ng/L (SD: 19,271) compared to 1,711 ng/L (SD: 3,835) in survivors (p<0.0001). The cut-off point of 1,769 ng/L showed a negative predictive value (NPV) of 95.3%, whereas 10,808 ng/L showed a positive predictive value (PPV) of 73.3%. The diagnostic performance of NT-ProBNP reached an AUC of 0.783 (95%CI: 0.731–0.829). Entering the potential confounding variables in a logistic regression model revealed that NT-ProBNP behaved like an independent risk factor. Grouping the NT-ProBNP values by every 300, 500, 1,000, and 2,000 ng/L increased the risk of mortality at 30 days by 3%, 5.1%, 10.5%, and 22%, respectively. Conclusion: The NT-ProBNP values at the time of CAP diagnosis are significantly higher among patients that die than those that survive the first 30 days, and it could be a good predictor of early mortality. NT-ProBNP has good overall accuracy and behaves like an independent risk factor. (Eurasian J Emerg Med 2016; 15: 30-8)