Effect of beta-blocker therapy on the risk of infections and death after acute stroke--a historical cohort study

Infections are a frequent cause for prolonged hospitalization and increased mortality after stroke. Recent studies revealed a stroke-induced depression of the peripheral immune system associated with an increased susceptibility for infections. In a mice model for stroke, this immunosuppressive effect was reversible after beta-blocker administration. The aim of our study was to investigate the effect of beta-blocker therapy on the risk of infections and death after stroke in humans. 625 consecutive patients with ischemic or hemorrhagic stroke, admitted to a university hospital stroke unit, were included in this historical cohort study. The effect of beta-blocker therapy on post-stroke pneumonia, urinary tract infections and death was investigated using multivariable Poisson and Cox regression models. 553 (88.3%) patients were admitted with ischemic stroke, the remaining 72 (11.7%) had a hemorrhagic stroke. Median baseline NIHSS was 8 (IQR 5-16) points. 301 (48.2%) patients received beta-blocker therapy. There was no difference in the risk of post-stroke pneumonia between patients with and without beta-blocker therapy (Rate Ratio = 1.00, 95%CI 0.77-1.30, p = 0.995). Patients with beta-blocker therapy showed a decreased risk for urinary tract infections (RR = 0.65, 95%CI 0.43-0.98, p = 0.040). 7-days mortality did not differ between groups (Hazard Ratio = 1.36, 95%CI 0.65-2.77, p = 0.425), while patients with beta-blocker therapy showed a higher 30-days mortality (HR = 1.93, 95%CI 1.20-3.10, p = 0.006). Beta-blocker therapy did not reduce the risk for post-stroke pneumonia, but significantly reduced the risk for urinary tract infections. Different immune mechanisms underlying both diseases might explain these findings that need to be confirmed in future studies.