Response to letter regarding article, "standard-dose intravenous tissue-type plasminogen activator for stroke is better than low doses".

BACKGROUND AND PURPOSE It remains uncertain whether lower dose intravenous tissue-type plasminogen activator (tPA) for stroke is as effective and safe as the standard dose. METHODS We analyzed data from the Thrombolysis Implementation and Monitor of Acute Ischemic Stroke in China (TIMS-China). Patients who were treated within 4.5 hours after symptom onset were included. These patients were divided into 5 groups according to tPA doses given: <0.5, 0.5 to 0.7, 0.7 to 0.85, 0.85 to 0.95, and ≥0.95 mg/kg. Symptomatic intracranial hemorrhage, mortality, and 90-day outcome assessed by modified Rankin scale were analyzed. RESULTS A total of 919 patients were enrolled. Among them, 9 had <0.5 mg/kg, 75 had 0.5 to 0.7 mg/kg, 131 had 0.7 to 0.85 mg/kg, 678 had 0.85 to 0.95 mg/kg, and 26 had ≥0.95 mg/kg. Because of sample sizes, only 0.5 to 0.7, 0.7 to 0.85, and 0.85 to 0.95 mg/kg groups were compared. Median tPA doses were 0.64, 0.79, and 0.90 mg, respectively. After adjustment for the baseline variables, there were no significant differences in mortality(5.41% versus 8.66% versus 7.36%; P=0.695) and symptomatic intracranial hemorrhage (0% versus 3.82% versus 1.46%; P=0.106). The 0.5 to 0.7 mg/kg group had less excellent recovery outcome (modified Rankin scale, 0-1) than 0.85 to 0.95 mg/kg group (41.89% versus 53.83%; odds ratio=0.58; P=0.031) at 90 days. The 0.70 to 0.85 mg/kg group had less functional independence outcome (modified Rankin scale, 0-2) than 0.85 to 0.95 mg/kg group (54.33% versus 64.51%; odds ratio=0.66; P=0.036) at 90 days. CONCLUSIONS Our study suggests that standard-dose intravenous tPA for stroke had more favorable outcome without increasing the risk of symptomatic intracranial hemorrhage than low-dose tPA. For Asian people, 0.9 mg/kg should be the optimal dose of tPA to treat acute ischemic stroke.