Context: The focus of thrombolytic therapy in acute stroke has been on favorable outcome at 3 months. Few studies have analyzed outcome at 24 hours. An early and reliable prediction of poor outcome has implications for clinical management and discharge planning. Abstract:Objective: To evaluate predictors of lack of improvement at 24 hours after receiving alteplase and their relationship with poor outcome at 3 months. Design, Setting, and Participants: Prospective cohort of consecutive patients with acute stroke who received alteplase and were admitted to a university hospital from January 1999 to March 2003. Participants were recruited from 2 academic centers in a major city in Ontario and 33 affiliated hospitals from 7 counties. Main Outcome Measures: Lack of improvement defined as a difference between the National Institutes of Health Stroke Scale score at baseline and at 24 hours of 3 points or less. Poor outcome at 3 months defined by a modified Rankin Scale score of 3 to 5 or death. Results: Among 216 patients with acute stroke who were treated with alteplase, 111 (51.4% ) had a lack of improvement at 24 hours. After adjusting for age, sex, and stroke severity, baseline glucose level on admission (odds ratio [OR] 2.89; 95% confidence interval [CI], 1.40- 5.99 for a glucose level > 144 mg/dL [ > 8 mmol/L]), cortical involvement (OR, 2.66; 95% CI, 1.36- 5.20), and time to treatment (OR, 1.01; 95% CI, 1.0- 1.02 for each 1 minute increase in time to treatment) were independent predictors of lack of improvement. At 3 months, 43 patients (20.2% ) had died; of the 170 survivors, 75 patients (44% ) had poor outcomes. After adjusting for age, sex, and stroke severity, lack of improvement at 24 hours was an independent predictor of poor outcome (OR, 12.9; 95% CI, 5.7- 29.6)- and death (OR, 7.5; 95% CI, 2.9- 19.6). Patients with a lack of improvement had longer lengths of hospitalization (14.5 vs 9.6 days; P=.02). Conclusions: Among patients with acute stroke treated with thrombolytic therapy, lack of improvement at 24 hours is associated with poor outcome and death at 3 months. Elevated glucose level, time to thrombolytic therapy, and cortical involvement were predictors of lack of improvement. Context: The focus of thrombolytic therapy in acute stroke has been on favorable outcome at 3 months. An early and reliable prediction of poor outcome has implications for clinical management and discharge planning. Abstract: Objective: To evaluate predictors of lack of improvement at 24 hours after receiving alteplase and their relationship with poor outcome at 3 months. Design, Setting, and Participants: Prospective cohort of consecutive patients with acute stroke who received alteplase and admitted admitted to a university hospital from January 1999 to March 2003. Participants were recruited from 2 academic centers in a major city in Ontario and 33 affiliated hospitals from 7 counties. Main Outcome Measures: Lack of improvement defined as a difference between the National Institutes of Health Stroke Scale score at baseline and at 24 hours of 3 points or less. Poor outcome at 3 months defined by a modified Rankin Scale score of 3 to 5 or deat h. Results: Among 216 patients with acute stroke who were treated with alteplase, 111 (51.4%) had a lack of improvement at 24 hours. After adjusting for age, sex, and stroke severity, baseline glucose level on admission (odds ratio [ OR] 2.89; 95% confidence interval [CI], 1.40-5.99 for a glucose level> 144 mg / dL [> 8 mmol / L] of three survivors (OR, 1.01; 95% CI, 1.0-1.02 for each 1 minute increase in time to treatment) were independent predictors of lack of improvement. At 3 months, 43 patients (20.2%) had died; of the 170 survivors After adjusting for age, sex, and stroke severity, lack of improvement at 24 hours was an independent predictor of poor outcome (OR, 12.9; 95% CI, 5.7-29.6) - and Patients with a lack of improvement had longer lengths of hospitalization (14.5 vs 9.6 days; P = .02). Conclusions: Among patients with acute stroke treated with (OR, 7.5; 95% CI, 2.9-19.6)Thrombolytic therapy, lack of improvement at 24 hours is associated with poor outcome and death at 3 months. Elevated glucose level, time to thrombolytic therapy, and cortical involvement were predictors of lack of improvement.