Disclosures: Nigar Dursun, MD: Allergan (Products/Services: Yes) (Consultant/Advisory Board, Research Grant includes principal investigator, collaborator or consultant and pending grants as well as grants already received)Ipsen (Products/Services: Yes) (Consultant/Advisory Board, Research Grant includes principal investigator, collaborator or consultant and pending grants as well as grants already received)Merz (Products/Services: Yes) (Consultant/Advisory Board, Research Grant includes principal investigator, collaborator or consultant and pending grants as well as grants already received)

Objective: Assess the time to retreatment after abobotulinumtoxinA injections in a Phase-III study of upper-limb spasticity due to cerebral palsy (CP).

Design: Randomized, double-blind study (NCT02106351). Setting : International study in 32 specialist centers. Participants : Children (2-17 years) with CP and spasticity in ≥1 upper-limb.

Interventions: 212 Children were randomized (1:1:1) to Cycle 1 injections of abobotulinumtoxinA 8U/kg, 16U/kg or 2U/kg (low-dose control) into the primary target muscle group (PTMG; elbow or wrist flexors) and additional upper-limb muscles. Eligibility for the next cycle was assessed at Week 16. At this visit, children who had a Modified Ashworth Scale score of 0 or a primary Goal Attainment Scale score of +2 were not eligible for reinjection. Children who showed sustained benefit returned every 6±2 weeks until they required retreatment, or until Week 52.

Main Outcome Measures: Proportion of children in Cycle 1 who required reinjection at Week 16, 22, 28, and 34 or later.

Results: Of the 208 children treated with abobotulinumtoxinA in Cycle 1 (mITT population, all doses), only 20.2% met retreatment criteria at Week 16. Most children met retreatment criteria at Weeks 22 and 28 (30.8% and 12.5%, respectively), while 22.5% met retreatment criteria at Week 34 or later. 20 children (9.6%) did not need reinjection within the 1 year study period and 10 (4.8%) were withdrawn. Conclusions: Estimating when a child being treated with botulinum toxin for spasticity will require retreatment is relevant to clinical planning. In this large, international study, almost two-thirds (65.8%) of children treated with abobotulinumtoxinA were retreated at Week 22 or later. The minimum recommended injection interval is 12 weeks; however longer injection intervals may improve patient quality of life, diminish caregiver burden, provide cost savings, and offer clinicians more flexibility.

Level of Evidence: Level I

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PM&R Meeting Abstracts - https://pmrjabstracts.org/abstract/time-to-retreatment-following-abobotulinumtoxina-injections-in-children-with-upper-limb-spasticity/