Elevated blood urea nitrogen/creatinine ratio is associated with poor outcome in patients with ischemic stroke

Dehydration may impair cerebral oxygen delivery and worsen clinical outcome in patients with acute ischemic stroke (AIS). We evaluated if elevated blood urea nitrogen to creatinine ratio (BUN/Cr) as a marker of dehydration was associated with poor clinical outcome in emergency department (ED) patients presenting with AIS.

We conducted a prospective cohort study using a stroke registry enrolling all ED patients with AIS from 10/2007 through 6/2009. Poor clinical outcome was defined as death, placement in a nursing home for purposes other than rehabilitation, or hospice within 30 days of ED presentation. A BUN/Cr ratio of ≥15 was considered elevated. (IQR). Logistic regression was performed adjusted for age >64 years, NIHSS >8, diabetes, prior CVA, and coma at presentation reporting odds ratios with 95% confidence intervals.

324 patients had a final diagnosis of AIS. 163 (50%) were female, 19 (6%) died, 44 (14%) received t-PA, and 89 (27%) had a poor clinical outcome. The median NIHSS, BUN and Cr were 4 (IQR 1-9), 14 mg/dL (IQR 11-21), and 1.02 mg/dL (IQR 0.87-1.27) respectively. The median BUN/Cr was 13.9 (IQR 10.6-18.5). The variables associated with a poor clinical outcome were: high NIHSS OR 6.5 (3.6-11.8), age >64 years OR 2.7 (1.5-5.0), and BUN/Cr ratio of ≥15 OR 2.2 (1.2-4.0).

An elevated BUN/Cr ratio in patients with AIS is associated with poor outcome at 30 days. Further study is needed to see if acutely addressing hydration status in ED patients with AIS can alter outcome.