Introduction of an NT-proBNP assay to an acute admission unit--a 2-year audit.
BACKGROUND
The differential diagnosis of dyspnoea is difficult due to the low predictive value of clinical and laboratory parameters. The elevated levels of NT-proBNP in congestive heart failure may improve diagnostic accuracy. We have evaluated the effect of the introduction of an NT-proBNP assay on hospital length of stay (LOS) and mortality.


METHODS
There were 11,853 AMAU patient episodes in the 22 months study period (March 2005-Dec 2006). An NT-proBNP assay was requested in 657 (5.5%) of these. Comparison between categorical variables such as diagnosis, NT-proBNP testing, LOS, and in-hospital mortality was made using Chi-square tests. Literature review suggested that an NT-proBNP cut-off >or=5000 ng/L should predict acute in-patient mortality. Logistic regression analysis was used to examine the association between such an elevated NT-proBNP level and outcomes.


RESULTS
Of the 396 patients with NT-proBNP <5000 ng/L, 8.1% died compared with 22.5% of the 178 patients dying with values >or=5000 ng/L (p<0.0001). An NT-proBNP >or=5000 ng/L was predictive of both LOS >or=9 days (odds ratios (OR) 1.54 (95% CI 1.06, 2.24: p=0.02) and LOS >or=14 days (OR=1.87 (95% CI 1.29, 2.71: p=0.0009). NT-proBNP requests increased over time, from 2.6% to 8.2% of all patients; the result fell in the diagnostic range for CHF in 60% of requests.


CONCLUSIONS
The introduction of an NT-proBNP was reflected in an appropriate but rapidly increasing pattern of requests from clinicians. High NT-proBNP levels predicted in-hospital mortality and longer LOS in an acute medical population.
Murtagh
Gillian
G
Division of Internal Medicine, St. James' Hospital, Ireland.
Canniffe
Carla
C
Mahgoub
Mohamed
M
Blake
Liam
L
McCarroll
Nuala
N
Crowley
Vivion
V
Bennett
Kathleen
K
Silke
Bernard
B
D000208:Acute Disease; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003955:Diagnostic Tests, Routine / Q000379:methods / Q000706:statistics & numerical data*; D004417:Dyspnea / Q000097:blood / Q000175:diagnosis / Q000401:mortality; D005260:Female; D006333:Heart Failure / Q000097:blood / Q000175:diagnosis / Q000401:mortality; D017052:Hospital Mortality; D006801:Humans; D007297:Inpatients / Q000706:statistics & numerical data; D007902:Length of Stay / Q000706:statistics & numerical data; D016015:Logistic Models; D008297:Male; D008485:Medical Audit; D008875:Middle Aged; D020097:Natriuretic Peptide, Brain / Q000097:blood*; D010446:Peptide Fragments / Q000097:blood*
D010446:Peptide Fragments; C109794:pro-brain natriuretic peptide (1-76); D020097:Natriuretic Peptide, Brain