Dosing of tissue plasminogen activator often differs from 0.9 mg/kg, but does not affect the outcome

Background: The safety and efficacy of low- and high-dose intravenous tissue plasminogen activator (t-PA) for the treatment of acute ischemic stroke are poorly understood. In this multicenter study, we examined the relationships between different doses of t-PA and outcome. Methods: Between 2006 and 2010, patients were enrolled if they were treated with t-PA on the basis of estimated body weight and on the subsequent availability of actual body weight. Based on the actual weight, patients were divided into lower (<0.85 mg/kg), standard (0.85-0.95 mg/kg), and higher (>0.95 mg/kg) t-PA dose groups. Differences in the outcomes of these groups were compared in terms of functional recovery (modified Rankin Scale [mRS] 0-1) at 3 months and the incidence of parenchymal hemorrhages on follow-up computed tomographic scans. Results: This cohort study included 272 patients: 171 (63%) patients received the standard t-PA dose, 62 (23%) a lower dose, and 39 (14%) a higher dose. At 3 months, 51% of the standard dose patients achieved a mRS score of 0 to 1, compared with 50% in the lower dose and 44% in the higher dose groups. Parenchymal hemorrhage occurred in 4.7%, 6.5%, and 7.7% of patients in standard, lower, and higher dose groups, respectively. Compared with standard dose groups, no significant differences in functional recovery and parenchymal hemorrhage were observed in the lower and higher dose groups. Conclusions: In clinical practice, the actual dose of t-PA often differs from the recommended dose of 0.9 mg/kg, but this has no significant impact on the outcome after t-PA treatment.