Prognostic Value of Brain Natriuretic Peptide in Acute Pulmonary Embolism
Coutance G, LePage O, Lo T, Hamon M
Crit Care. 2008;12:R109
Pulmonary embolism (PE) is notoriously difficult to diagnose, but risk stratification for adverse outcomes among patients diagnosed with PE is even more difficult. Cardiac troponins and brain natriuretic peptide (BNP) have been suggested as tools to predict relevant outcomes and thus, to assist with patient treatment decisions. However, the studies to date have been relatively small and with inconclusive findings. The authors of this study sought to determine the value of BNP in predicting clinical outcomes in patients with PE by performing a systematic review and meta-analysis of the published studies to date. By combining data from 868 patients in 12 studies with appropriate outcomes, they found that elevated BNP levels were associated with an increased risk for death and serious adverse events (odds ratios, respectively, were 6.1 and 7.5), and the predictive value of a negative test (normal BNP level) was 99%.
Viewpoint
The results of this study suggest that BNP (and presumably the similar N-terminal pro-BNP) levels may be used to assess patients with PE for the development of adverse clinical outcomes, such as death. However, the data are insufficient to substantiate this conclusion. While the odds ratios for these outcomes are truly elevated, the specificity of the BNP assays is sufficiently low (approximately 50%) that the value of BNP for predicting a relatively uncommon event like death is poor (positive predictive value approximately 13%). The predictive value might be improved by measuring BNP levels in the most seriously ill patients (eg, submassive or massive PE), but the current data do not examine BNP performance in this subgroup and risk stratification in these patients may be less necessary anyway. What this study does confirm is that normal BNP levels are associated with a very low risk for adverse outcomes and death. With a relatively high sensitivity (approximately 92%), the predictive value of a negative BNP result is very high (99%). This means that patients hospitalized for PE with initially normal BNP levels are very unlikely to have an adverse clinical outcome and thus, management may be different in terms of intensity of monitoring and/or consideration of thrombolytic therapy.
Abstract