Introduction of an NT-proBNP assay to an acute admission unit — A 2-year audit☆
Received 17 August 2007; received in revised form 12 February 2008; accepted 27 April 2008. published online 21 July 2008.
Abstract
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 ≥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 ≥5000 ng/L (p<0.0001). An NT-proBNP ≥5000 ng/L was predictive of both LOS ≥9 days (odds ratios (OR) 1.54 (95% CI 1.06, 2.24: p=0.02) and LOS ≥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.
Conclusion
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.
aDivision of Internal Medicine, St. James' Hospital, Ireland
bClinical Biochemistry, St. James' Hospital, Ireland
cDepartment of Therapeutics and Pharmacology, Trinity College Dublin, Trinity Centre at St. James' Hospital, Dublin 8, Ireland
Corresponding author. Department of Pharmacology and Therapeutics, Trinity Centre for Health Sciences, St James' Hospital, James' Street, Dublin 8. Ireland. Tel.: +353 1 608 1563; fax: +353 1 453 9033.
☆ Data previously presented at the Meeting of the Irish Association of Internal Medicine April 2007 and the Irish Society of Angiology 6th Annual Meeting November 2006.
ABSTRACT