Effectiveness of repeated treatment with botulinum toxin type A across different conditions.

This review assessed the overall effectiveness of repeated treatments with botulinum toxin type A (BoNTA) across different conditions, as documented in the published literature. Forty-four original research articles reporting on 16 different conditions were identified that included data on the duration or efficacy of multiple treatments with BoNTA. All of the 44 studies found sustained or enhanced improvement in efficacy and/or duration over the follow-up period, which ranged from a few treatments to more than 10 years. Dosages did not change over time in 22 of the studies, increased in 4 studies, were not reported over time in 17 studies, and tended to increase then decrease in one study. Seven studies reported a statistically significant increase in the efficacy or duration of BoNTA over time. Results suggest that continued benefit with repeated BoNTA treatment is widely reported in the literature.