Background: The Cervical Dystonia Patient Registry for Observation of OnabotulinumtoxinA Efficacy (CD PROBE;NCT00836017) is a prospective, observational, multicenter, real-world registry designed to assess the safety, effectiveness, and treatment utilization following multiple treatments of onabotulinumtoxinA.

Methods: Subjects were naïve to botulinum toxin, new to practice, or had not received toxin in ≥ 16 weeks if in a clinical trial. Dosages and treatment intervals varied due to the real-world design. Descriptive and inferential statistics evaluated changes over 3 treatments.

Results: 1046 subjects enrolled. Subjects were 74.4% female, 63.5% toxin-naïve, mean age 58.0 ± 14.7 years. The mean dose over 2481 treatment sessions was 189. 8 ± 87.1U, with average treatment intervals of 14.6 and 15.1 weeks. The mean Toronto Western Spasmodic Torticollis Rating Scale Total score in subjects who completed all assessments (n=479) decreased from 39.2 at baseline to 27.1 at final visit (P<.0001). A high percentage of physicians reported improvement in Clinician Global Impression of Change after initial assessment; this significantly increased at final assessment (n=479, 91.2% vs 95.0%; P<.0001). Similarly, a high percentage of subjects reported improvement in Patient Global Impression of Change after initial assessment, which significantly increased at final assessment (n=470, 83.0% vs 91.7%; P<.0001). Significant reductions in all Cervical Dystonia Impact Profile-58 scores were observed (n=407). Overall, 26.2% of subjects reported adverse events, including muscular weakness (7.0%) and dysphagia (6.4%).

Conclusions: Results indicate robust improvement in clinical ratings and excellent tolerability following onabotulinumtoxinA treatment of CD.