Background: B-type natriuretic peptide (BNP) levels are reliably elevated in patients with congestive heart failure (CHF) and therefore helpful in its diagnosis. However, kidney disease results in elevated BNP levels independently of CHF. Accordingly, the impact of kidney disease on the benefit of BNP testing needs to be scrutinized.
Methods: This study evaluated patients with and without kidney disease [glomerular filtration rate (GFR) less than 60 mL/min/1.73 m(2)) presenting with acute dyspnea. A total of 452 consecutive patients (240 with kidney disease and 212 without kidney disease) were randomly assigned to a diagnostic strategy with (BNP group) or without (control group) the use of BNP levels provided by a rapid bedside assay.
Results: Patients with kidney disease were older, more often had CHF as the cause of acute dyspnea, and more often died in-hospital or within 30 days as compared to patients without kidney disease. In patients without kidney disease, BNP testing significantly reduced median time to discharge (from 9.5 days to 2.5 days) (P= 0.003) and total cost of treatment (from 7184 dollars to 4151 dollars) (P= 0.004). In contrast, in patients with kidney disease, time to discharge and total cost of treatment were similar in both groups.
Conclusion: When applying BNP cut-off values without adjustment for the presence of kidney disease, the use of BNP levels does significantly improve the management of patients without kidney disease, but not of those with kidney disease.