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Abstract 72: Comparative Effectiveness of Intravenous Thrombolysis in patients with Mild Ischemic Stroke


 Background:
 One third of patients with initially mild strokes have unfavorable outcome, and the efficacy of intravenous thrombolysis (IVT) in those patients has not proven. This study aimed to evaluate the comparative effectiveness of IVT over no thrombolysis in patients with mild ischemic stroke presenting within 4.5 hours of onset.
 
 
 Methods:
 From a multicenter prospective stroke registry database, we identified acute ischemic stroke patients (1) who were aged 18 years or more, (2) whose neuroimaging confirmed relevant acute ischemic lesions, (3) who were presented within 4.5 hours of onset, and (4) whose initial NIHSS scores were 5 points or less. Matching and inverse probability of treatment weighting (IPTW) by propensity score (PS) were used to remove baseline imbalance between the IVT and no treatment groups. Further adjustments for potential confounders were made in the IPTW analysis. The adjusted odds ratios (ORs) and their 95% confidence intervals (CIs) of IVT compared to no treatment were calculated for 3-month modified Rankin Scale (mRS) 0-1 (primary efficacy outcome), the full distribution of mRS scores (sedoncary efficacy outcome, by an ordinal logistic regression analysis), and symptomatic hemorrhagic transformation (sHT, safety outcome).
 
 
 Results:
 Between April 2008 and May 2012, 13,117 stroke patients were hospitalized to the 12 participating centers. Among them, 1,386 subjects met the eligibility criteria, and 194 (14.0%) were treated with IVT. The proportions of 3-month mRS 0-1 were not different between the IVT and no treatment groups (71% vs. 75%, p=0.18), but those of sHT were different (4.1% vs. 0.5%, p<0.001).
 
 The adjusted ORs (95% CIs, p values) were 1.46 (0.95-2.25, 0.08) by PS-matching and 1.47 (0.77-2.82, 0.24) by IPTW for 3-month mRS 0-1; 1.05 (0.73-1.49, 0.80) by PS-matching and 1.09 (0.65-1.81, 0.75) for an increment of 3-month mRS score; and 7.47 (1.52-36.64, 0.01) by PS-matching and 3.85 (0.82-18.06, 0.09) by IPTW for sHT.
 
 Conclusion:
 This comparative effectiveness analysis based on the large multicenter stroke registry database failed to prove the superiority of intravenous thrombolysis over no treatment in patients with mild ischemic stroke.
