Pooled analysis of the safety of botulinum toxin type A in the treatment of poststroke spasticity

OBJECTIVE: To examine the safety of botulinum toxin type A (BTX-A). DESIGN: Analysis of pooled data of 9 double-blind, placebo-controlled studies of patients with spasticity after stroke. SETTING: University hospitals and specialty rehabilitation centers in the United States. PARTICIPANTS: A total of 482 patients with upper-limb spasticity and 310 with lower-limb spasticity (overall mean age, 58y; 60% men). INTERVENTION: Treatment with BTX-A (n=534; 1-3 treatments; mean dose, 231U) or placebo (n=258). MAIN OUTCOME MEASURE: Adverse events. RESULTS: Most patients (69%) received only 1 treatment with BTX-A. Patients were followed for a mean of 17.8 weeks (range, 0.1-44.7wk) after each treatment. A total of 352 (65.9%) patients in the BTX-A group and 163 (63.2%) in the placebo group reported at least 1 adverse event (P=.475). The most frequent adverse events reported by patients (>5% but <10% in either group) were respiratory infection, seizures, incoordination, and injection site pain, none of which occurred at a significantly higher rate in the BTX-A group (all P>.05). The majority of adverse events were rated as mild or moderate in severity. Only nausea was reported at a significantly higher rate in the BTX-A group (12/534 2.2%]) than the placebo group (0/258) (P=.011); in contrast, injection site pain, chest pain, and allergic reaction were reported significantly more frequently in the placebo group. CONCLUSIONS: BTX-A has an acceptable safety profile for treatment of patients with focal spasticity following stroke, a population in which adverse events and comorbidities are common.