Abstract
Objectives
Blood urea nitrogen (BUN) has been shown to independently predict short- and intermediate-term
outcomes in patients with acute myocardial infarction (AMI). We aimed to assess the
additive predictive value of BUN beyond estimated glomerular filtration rate (eGFR)
in AMI patients with an 8.6-year follow-up.
Methods
This retrospective, observational single-centre study included 1332 consecutive AMI
patients (median age 64 years, 58.4% male). BUN, creatinine and eGFR were determined
at hospital admission.
Results
During a median follow-up of 8.6 years (interquartile range [IQR] 4.0–11.6), 408 patients
(30.6%) experienced the study endpoint of cardiovascular mortality. BUN (median 17.0 mg/dL
[IQR 13.5–22.7]) was a significant predictor of cardiovascular mortality in univariate
Cox regression (hazard ratio (HR) per 1 standard deviation increase 2.10, 95% confidence
interval [CI] 1.94–2.28, p < .001). This association remained significant after multivariable adjustment for
demographics, clinical variables and eGFR (adjusted HR 1.52 [CI 1.16–2.00, p = .003]). The association between BUN and outcome was more pronounced in patients
with eGFR >60 mL/min/1.73m2 (HR 2.81 [CI 2.20–3.58, p < .001]). The discriminatory abilities (Harrell's C-statistic) for BUN, eGFR and
creatinine were 0.75, 0.76 and 0.67, respectively. The addition of BUN to eGFR significantly
improved the C-statistic (0.78, p for comparison = 0.017), net reclassification (23.7%, p < .001) and integrated discrimination (2.9%, p < .001).
Conclusions
Circulating BUN on admission is an independent predictor of long-term cardiovascular
mortality in AMI patients and adds predictive power beyond eGFR. BUN reflects not
only kidney function, but also acute haemodynamic and neurohumoral alterations during
AMI, and may help to identify high-risk patients.
Keywords
Abbreviations:
AMI (acute myocardial infarction), BUN (blood urea nitrogen), CI (confidence interval), CKD-EPI (Chronic Kidney Disease Epidemiology Collaboration), eGFR (estimated glomerular filtration rate), HR (hazard ratio), IDI (integrated discrimination improvement), IQR (interquartile range), NRI (net reclassification improvement), NT-proBNP (N-terminal pro-B-type natriuretic peptide), SD (standard deviation), STEMI (ST-elevation myocardial infarction)To read this article in full you will need to make a payment
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Article info
Publication history
Published online: July 30, 2018
Accepted:
July 22,
2018
Received in revised form:
June 28,
2018
Received:
March 21,
2018
Identification
Copyright
© 2018 European Federation of Internal Medicine. Published by Elsevier B.V. All rights reserved.