Prospective observational study of step-up dose treatment with onabotulinumtoxinA in patients with spasticity

OBJECTIVE: To evaluate the safety and effectiveness of "step-up dose" onabotulinumtoxinA (401-600 units per treatment session) in patients with upper and lower limb spasticity. DESIGN: Multicentre, prospective, observational, single-arm investigation. SUBJECTS: A convenience sample of 109 patients with upper and lower limb spasticity scheduled to receive their first or second step-up dose onabotulinumtoxinA. METHODS: The study primarily evaluated the safety of step-up dose onabotulinumtoxinA by summarizing adverse events. Effectiveness was evaluated as a secondary objective. RESULTS: Of the safety population comprising 107 patients, 49 (45.8%) experienced at least 1 adverse event, with coronavirus disease 2019 and nasopharyngitis being the most frequent. Five patients (4.7%) reported adverse events related to onabotulinumtoxinA or injection procedure. These safety findings were generally consistent with those previously reported, while reduction of muscle tone and subsequent clinical benefits were suggested by the Modified Ashworth Scale and patient/physician-reported outcomes. CONCLUSION: To the best of our knowledge, this is the first study to prospectively evaluate the safety and effectiveness of onabotulinumtoxinA at doses above 400 units given simultaneously for upper and lower limb spasticity. No new safety concern was identified for this "step-up dose" treatment.