Long-Term Effect of Intravenous Thrombolytic Therapy in Acute Stroke: Responder Analysis versus Uniform Analysis of Excellent Outcome

Abstract

Background: Knowledge regarding functional improvement over time and long-term outcome after intravenous thrombolysis in acute ischaemic stroke is limited. The aim of this study was to compare a uniform assessment of outcome with an assessment taking the baseline stroke severity into account (responder analysis). Methods: Fifty-seven patients were assessed with the modified Rankin Scale at 3, 6 and 12 months and a comparison was made between a uniform assessment and a responder analysis of excellent outcome. Results: Between 3 and 12 months, 74% of the patients had a stable functional outcome and 22% improved. Excellent outcome at 12 months was similar in the uniform analysis (37%) and the responder analysis (35%). The individual patients having an excellent outcome differed, however, using the two methods. Using a responder analysis the number of patients with excellent outcome decreased in mild stroke patients by 40%, but increased in severe stroke patients by 43%. Conclusions: Short-term outcome is sustained at 12 months, but major improvement does not occur between 3 and 12 months. A responder analysis of long-term excellent outcome provided a balanced measure of outcome reflecting the drug-related potential of improvement in all stroke severity subgroups, whereas a uniform analysis provided a measure of outcome mainly in mild stroke patients. These results suggest that a responder analysis should be considered for the assessment of outcome after treatment for acute stroke.