To examine the relationship between dose and treatment intervals of onabotulinumtoxinA for adult limb spasticity in real-world practice.

Better understanding the relationship between dose and treatment intervals with onabotulinumtoxinA can help improve clinical strategies to manage limb spasticity.

The prospective, observational, international Adult Spasticity International Registry (ASPIRE; NCT01930786) collected data for multiple etiologies over 2 years (N=730). OnabotulinumtoxinA dose and treatment intervals were at the physician's discretion. Treatment intervals for patients with >1 treatment visit (N=2373 intervals) were categorized by the length between treatments: <12, 12-14, 15-17, 18-20, and ≥21 weeks. Treatment adherence was defined as those receiving ≥3 treatment sessions with onabotulinumtoxinA over 2 years. Patient satisfaction items were assessed, and adverse events (AEs) captured.

Overall, onabotulinumtoxinA doses were constant over treatment interval groups, with the lowest mean dose 335U (for ≥21 weeks) and highest dose 387U (for 12-14 weeks). Patients naïve to toxin at baseline received slightly lower doses in each treatment interval group than non-naïve, with respective doses ranging from 305-372U and 346-396U. Most patients received doses ≤400U across all treatment interval groups: <12 (63%), 12-14 (66%), 15-17 (70%), 18-20 (75%), and ≥21 (76%) week groups. Dose slightly increased over treatment sessions, from 355U at session 2 to 394U at session 7. Treatment-adherent patients reported high rates of satisfaction over treatment sessions: 81-92% stated their most recent onabotulinumtoxinA treatment helped their spasticity, 73-82% were satisfied/extremely satisfied with how long they felt onabotulinumtoxinA working, and 91-96% planned to continue using onabotulinumtoxinA. The 3 most commonly reported AEs were fall (5.5%), urinary tract infection (2.6%), and muscular weakness (2.6%).

Dose of onabotulinumtoxinA to treat adult spasticity remained consistent over treatment sessions regardless of treatment interval, with most patients receiving onabotulinumtoxinA within approved dose ranges. High patient satisfaction was observed, with no new safety concerns.