Background: Mortality due to stroke has declined over the past 2 decades. Intravenous thrombolytic therapy improves the functional outcome, but its contribution in reducing stroke mortality is not clear. We aim to examine the trend of ischemic stroke case fatality in recent years in relation to the utilization of thrombolytic therapy.
Methods: We examined the trend of risk-adjusted one-year mortality and intravenous thrombolytic therapy in Medicare beneficiaries aged ≥65 years who were hospitalized between January 1, 2009 and December 31, 2013 with a primary discharge diagnosis of acute ischemic stroke. The data of the patient information were obtained from the Medicare Provider Analysis and Review file. Cox proportional hazards models were generated to adjust for patient demographics and comorbidities. All statistical analyses were performed using SAS Version 9.4 software.
Results: This study included 1,165,960 Medicare Beneficiaries. The one-year risk-adjusted mortality showed a steady declined from 29.7% in 2009 to 24.4% in 2013, 17.8% decline over the five year period. This was parallel to the 59.7% increase of intravenous thrombolytic therapy utilization, from 5.21% in 2009 to 8.32% in 2013. The mortality decline was only observed in patients who received intravenous thrombolytic therapy (HR 0.86; 95% CI 0.82-0.91), but not in those who did not receive thrombolytic therapy (HR 0.99; 95% CI 0.97-1.01) (Table).
Conclusion: The increasing use of intravenous thrombolytic therapy was associated with decline in risk-adjusted one-year mortality after ischemic stroke. The reasons for the mortality decline among those who received thrombolytic therapy needs further explanation.