Relationship between Kidney Dysfunction and Ischemic Stroke Outcomes: Albuminuria, but Not Estimated Glomerular Filtration Rate, Is Associated with the Risk of Further Vascular Events and Mortality after Stroke.

BACKGROUND AND OBJECTIVE: Estimated glomerular filtration rate (eGFR) and albuminuria are known to be associated with ischemic stroke outcomes. In this study, we investigated the longitudinal relationships of the two markers with mortality, vascular events and functional outcomes in a stroke cohort.

METHODS: A total of 295 patients with acute ischemic stroke were prospectively recruited in a single center between May 2012 and February 2015. Renal dysfunction was defined as a decreased eGFR (<60 mL/min/1.73 m2) or albuminuria (urine albumin-to-creatinine ratio ≥ 30 mg/g). Good functional outcome at 6 months was defined as a modified Rankin scale score ≤ 2, and the occurrence of major vascular events (stroke, acute coronary syndrome or peripheral artery occlusion) or death was monitored. The associations between renal dysfunction and mortality, major vascular events, and 6-month functional outcome were evaluated by the Cox proportional hazards model and logistic regression analysis. Unadjusted and adjusted hazards ratios (HRs), odds ratios (ORs), and 95% confidence intervals (CIs) were obtained. A Kaplan-Meier survival curve for composite adverse events (major vascular events or death) was also computed according to the presence or absence of albuminuria.

RESULTS: Albuminuria, not eGFR, was significantly associated with mortality (P = 0.028; HR 2.15; 95% CI 1.09-4.25) and major vascular events (P = 0.044; HR 2.24; 95% CI 1.02-4.94) in the multivariate Cox proportional hazards models adjusting for age, sex, diabetes, hypertension, current smoking, atrial fibrillation, previous stroke, alcohol history, initial National Institutes of Health Stroke Scale (NIHSS) score and eGFR. In addition, albuminuria was negatively associated with 6-month functional outcome in the multivariate logistic regression analysis adjusting for age, sex, diabetes, hypertension, current smoking, atrial fibrillation, previous stroke, alcohol history and eGFR (P = 0.001; OR 0.36; 95% CI 0.20-0.65), but the association disappeared when NIHSS score was additionally adjusted (P = 0.519; OR 0.79; 95% CI 0.39-1.60). Furthermore, the patients with albuminuria had a significantly higher rate of composite adverse events than the patients without albuminuria (P < 0.001 by log-rank test).

CONCLUSIONS: Albuminuria seems a more useful clinical indicator than eGFR in evaluating the risk of adverse outcomes including further vascular events and death in patients with ischemic stroke.