Renal function predicts survival in patients with acute ischemic stroke

Background: Among patients with acute ischemic stroke, impaired kidney function has been shown to increase the mortality risk, but the shape of this relationship has not been evaluated in detail. Methods: We estimated the glomerular filtration rate (eGFR) at the time of hospitalization in 1,175 consecutive patients hospitalized with acute ischemic stroke at the Beth Israel Deaconess Medical Center and examined the shape of the association between eGFR and all-cause mortality. Results: There were 508 deaths during a median follow-up of 40.3 months, resulting in a 'U'-shaped relationship between eGFR and all-cause mortality. The curve was relatively flat between 75 and 110 ml/min/1.73 m² but increased sharply at lower and higher levels of eGFR (test for nonlinearity: p < 0.0001). Conclusions: Among patients with acute ischemic stroke, a reduced or highly elevated eGFR at hospital admission is associated with a higher mortality rate compared to patients with moderate levels of eGFR.