Elevated urea level is associated with poor clinical outcome and increased mortality post intravenous tissue plasminogen activator in stroke patients

Abstract

Background: Renal dysfunction is associated with poor outcomes in ischaemic stroke but remains unproven post intravenous thrombolysis. We studied the renal function in stroke patients treated with intravenous tissue plasminogen activator (IV tPA).

Methods: We retrospectively analysed consecutive ischaemic stroke patients treated with IV tPA (0.9 mg/kg) from January 2003 to December 2011. Collected data included demographics, medical histories, stroke severity measured by National Institutes of Health Stroke Scale (NIHSS), serum urea, creatinine, estimated glomerular filtration rate (eGFR), platelet, white cell count and international normalised ratio (INR) at baseline. Poor clinical outcome was defined as modified Rankin Scale (mRS) of 2 to 6 at 3 months. Logistic regression analysis was performed to test the association between renal function and clinical outcomes adjusted for confounders.

Results: In the 378 patients included, the median age was 72 (IQR=62-81) years, 54.2% were male. Median baseline NIHSS was 12 (IQR=8-18). There was a statistically significant association between all three renal function markers. After adjustments for confounding factors, baseline urea was significantly associated with poor outcome (OR=1.100; 95% CI 1.010-1.198 per mmol/L; p=0.028) and mortality (OR=1.117; 95% CI 1.027-1.213 per mmol/L; p=0.009), eGFR was associated with mortality (OR=0.984; 95% CI 0.970-0.998 per mL/min/1.73 m(2); p=0.026) but not poor outcome (OR=0.994; 95% CI 0.983-1.004 per mL/min/1.73m(2); p=0.230), and serum creatinine was not significant for poor outcome (OR=1.037; 95% CI 0.967-1.113 per 10 μmol/L; p=0.306) or mortality (OR=1.032; 95% CI 0.979-1.088 per 10 μmol/L; p=0.238). No association was observed between ICH and any renal function test.

Conclusions: Elevated serum urea was independently associated with poor clinical outcome and mortality in acute ischaemic stroke patients treated with IV tPA.

Keywords: Acute stroke; Glomerular filtration rate; Intravenous thrombolysis; Mortality; Outcome; Renal function; Urea.