Background: Few large studies exist on volume depletion and its association with outcomes in acute ischemic stroke (AIS) patients. A common marker of volume status is the calculated blood urea nitrogen (BUN) to serum creatinine (SCr) ratio. We examined the association between admission volume depletion (BUN/SCr > 15) and discharge outcome in AIS patients.
Methods: Consecutive patients (March 2014 - April 2015) who presented with AIS to our Comprehensive Stroke Center (CSC) were retrospectively analyzed. Demographics, medical history, imaging, initial lab values, stroke severity (NIHSS), and discharge disposition were recorded. Patients with BUN/SCr <= 15 and > 15 were compared and good outcome defined as discharge home. We performed logistic regression adjusting for admission NIHSS and age.
Results: We identified 776 patients who met inclusion criteria. Patients with BUN/SCr >15, were older (median 61 vs. 68, p<0.001), more often female (43.5 vs. 59.6%, p<0.001), and had atrial fibrillation (9 vs. 16%, p=0.004). Greater proportions presented with a hyperdense artery sign (7.1 vs. 12.9%, p=0.010) and developed an in-hospital UTI (2.8 vs. 5.9%, p=0.034). Volume depleted patients had increased LOS (3 vs. 4 days, p=0.049) and higher in-hospital mortality (6.2 vs. 12.6%, p=0.003) with fewer discharged home (57.7 vs. 44.9%, p=0.001). A BUN/SCr >15 was associated with lower odds of good outcome at discharge (OR=0.57, 0.42 - 0.78; p< 0.001), this relationship persisted after adjusting for known predictors (OR=0.70, 0.49 -1.00; p=0.055).
Conclusions: After controlling for age and NIHSS, volume depletion in AIS patients estimated by BUN/SCr ratio was associated with poor discharge outcome, complicated hospital course, increased LOS, and in-hospital mortality. This simple ratio can be used in the early evaluation and treatment of AIS. However, multi-center prospective studies are needed to determine if volume correction is confounding this association.