Retrospective evaluation of the dose of Dysport and BOTOX in the management of cervical dystonia and blepharospasm: the REAL DOSE study.

The purpose of this study is to evaluate the real-world dose utilization of Dysport and BOTOX for cervical dystonia and blepharospasm. Six investigational sites (five countries) were identified. Investigators abstracted utilization data for patients who received Dysport before switching to BOTOX or BOTOX before switching to Dysport. Patients were identified during scheduled clinic visits and selected if they met study criteria, which included treatment for at least 2 consecutive years (at least 1 year with Dysport or BOTOX, then switched and maintained on BOTOX or Dysport for at least another year). A total of 114 patients were included in the assessment. Ratios of mean dose for Dysport to BOTOX ranged from a low of 2:1 to a high of 11:1. Thirty-one percent of patients fell into the Dysport-to-BOTOX ratio grouping of 5:1 to less than 6:1; 30% of patients had a mean ratio of Dysport to BOTOX of 4:1 to less than 5:1; and only 21% of all patients evaluated fell into the Dysport-to-BOTOX ratio grouping of 3:1 to less than 4:1. Results are consistent with United Kingdom labeling for botulinum toxins stating that units of different serotype A toxins are not interchangeable and simple dose-conversion factors are not applicable.