Clinical Question: In patients with pulmonary disease, can brain natriuretic peptide (BNP) testing effectively guide therapy?
Setting: Emergency department
Study Design: Randomized controlled trial (single-blinded)
Synopsis: This report is a subgroup analysis of the BASEL study (Mueller C, et al. Use of B-type natriuretic peptide in the elevation and management of acute dyspnea. N Engl J Med 2004;350:647–54), which showed the effectiveness of BNP testing in the management of patients with heart failure who present with acute decompensation to an emergency department. In this analysis, 226 patients had a history of pulmonary disease: 72 percent had a history of chronic obstructive pulmonary disease or asthma. Other pulmonary diseases included pneumonia, pulmonary embolism, and interstitial lung disease.
Patients were assigned randomly (allocation concealed) to usual care supplemented by a rapid BNP test, or the usual diagnostic protocol without knowledge of BNP level. Physicians were advised that a BNP level lower than 100 pg per mL (100 ng per L) made heart failure unlikely, a result greater than 500 pg per mL (500 ng per L) made heart failure highly likely, and that intermediate values required additional information and clinical judgment to make the diagnosis.
The BNP level was not measured during any subsequent hospitalization. Outcomes were assessed by a group blinded to treatment assignment. Heart failure was the major cause of acute dyspnea in 39 percent of patients, closely followed by an exacerbation of obstructive pulmonary disease (33 percent) and pneumonia (16 percent). Patients in the BNP group were less likely to be admitted (81 versus 91 percent; P = .034) and spent less time in the hospital (nine versus 12 days; P = .001).
The median cost of care was lower in the BNP group ($4,841 versus $5,671; P = .008). In-hospital mortality was similar in both groups. These results parallel the results demonstrated in the complete BASEL study.
Bottom Line: In patients with preexisting pulmonary disease, BNP testing in the emergency department can effectively distinguish an exacerbation caused by heart failure from one caused by pulmonary disease. As a result, hospitalizations are fewer, probably because of the initiation of more appropriate therapy in the emergency department. Also, the duration of the hospital stay is shorter and the cost is lower. (Level of Evidence: 1b)