Renal dysfunction as an independent predictor of outcome after aneurysmal subarachnoid hemorrhage: a single-center cohort study.

BACKGROUND AND PURPOSE: Acute kidney injury occurs in 1% to 25% of critically ill patients with small increases in creatinine adversely affecting outcome. We sought to determine the burden of acute kidney injury in patients with aneurysmal subarachnoid hemorrhage and whether this dysfunction affects outcome. METHODS: Between 1996 and 2008, 787 consecutive patients with aneurysmal subarachnoid hemorrhage were enrolled in our prospective database. Demographics, serum creatinine levels, and discharge modified Rankin scores were recorded, and changes in creatinine clearance were calculated. A multiple logistic regression was performed using known predictors for poor outcome after aneurysmal subarachnoid hemorrhage in addition to burden of contrast-enhanced imaging and change in creatinine clearance. RESULTS: One hundred seventy-nine (23.1%) patients were at risk for renal failure during their hospitalization. In a multivariate model, those patients who developed risk for renal failure were twice as likely to have a poor 3-month outcome (OR, 2.01; P=0.021). Survival curves comparing those not at risk, those at risk (increasing severity classes Risk, Injury, and Failure, and the 2 outcome classes Loss and End-Stage Kidney Disease [RIFLE] R), and those with renal injury or failure (RIFLE I and F) demonstrated that risk of death increases significantly as one progresses through the RIFLE classes (log rank, P<0.0001). CONCLUSIONS: In a large, consecutive series of prospectively enrolled patients with aneurysmal subarachnoid hemorrhage, we demonstrate, using the newly defined RIFLE classification for risk of renal failure, that even seemingly insignificant decreases in creatinine clearance are associated with significantly worse 3-month outcomes. This study highlights the importance of close surveillance of renal function and stresses the value of renal hygiene in the aneurysmal subarachnoid hemorrhage population.