Abstract 2375: Oseltamivir Treatment Reduces the Risk of Stroke Following Influenza Infection

Abstract

Background: Influenza infection is known to trigger the incidence of heart attack and ischemic stroke. Seasonal influenza epidemics are associated with an increased risk of cardiovascular diseases, including ischemic stroke. Influenza vaccine has been shown to reduce the risk of myocardial infarction and stroke. The antiviral drug oseltamivir has been shown to reduce the severity and duration of influenza symptoms and the risk of hospitalization in patients diagnosed with influenza. We conducted a retrospective cohort study to examine the impact of oseltamivir treatment on the risk of stroke and transient ischemic attack (TIA) following influenza in adults. Methods: Anonymous, patient-level medical and pharmaceutical claims data from May 2000 to September 2006 were obtained from a managed care database. We selected patients diagnosed with influenza who were prescribed oseltamivir within 1 day before or 2 days after influenza diagnosis (oseltamivir group) and compared them to patients who were not prescribed any antiviral treatment for influenza (control group). The incidence of stroke or TIA in the 6 months following influenza diagnosis in the two groups was compared using multivariate analyses adjusted for factors including age, gender, and history of risk factors for stroke, and differences expressed as hazard ratios (HR) with 95% confidence intervals (CI). Results: There were 151,930 eligible patients aged ≥18 years: 49,238 patients in the oseltamivir group, and 102,692 patients in the control group. Treatment with oseltamivir was associated with a significant 29% reduction in the risk of stroke or TIA at 6 months following an influenza diagnosis (HR=0.71; 95% CI 0.61– 0.81). Significant reductions in risk were also observed at 1 and 3 months. The effect of oseltamivir on the risk of stroke or TIA was more pronounced in patients aged ≥40 years: significant risk reductions were observed at months 1 (HR=0.50; 95% CI 0.37– 0.68), 3 (HR=0.62; 95% CI 0.51– 0.75), and 6 (HR=0.73; 95% CI 0.63– 0.84). In those aged <40, HR at 6 months was 0.56 (95% CI: 0.37– 0.86). Conclusions: Prescription of oseltamivir after influenza is associated with a reduced risk of stroke or TIA. Our results, once confirmed by randomized studies, offer a novel approach to prevent stroke and TIA.