Objective: To assess, the duration of treatment effect for incobotulinumtoxinA treatment intervals using a pooled analysis of 2 phase 3 clinical studies in upper-limb post-stroke spasticity (ULPSS).
Background: The efficacy and safety of incobotulinumtoxinA in ULPSS has been confirmed in 2 phase 3 studies. Study 0410 included a randomized placebo-controlled period and an open-label extension (OLEX). OLEX reinjection intervals were flexible (≥12 week intervals with doses ≤400U). Study 3001 included fixed 12-week treatment intervals (TIs). In study 0410, investigators and subjects mutually determined the need for re-injection on the basis of pre-specified criteria (eg, Ashworth scale scores, investigator’s clinical impression).
Design/Methods: All TIs between 2 consecutive incobotulinumtoxinA injections were included, except TIs prior to the end of study visit and those with doses <300U. Outliers and factors other than a medical need for re-injection (eg, visit scheduling) were accounted for using duration thresholds applied during the analysis; the number of subjects with ≥1 TI above a threshold was calculated.
Results: A total of 347/437 incobotulinumtoxinA TIs met the inclusion criteria (range of re-injection intervals observed: 9–49 weeks). Over half (54.8%) of the re-injections were administered at week ≥14. The mean incobotulinumtoxinA TI was 15.46 weeks (standard devation: 4.63 weeks). A majority of subjects (59.1%) had ≥1 TI with re-injection at week ≥16; 33.1% of subjects had 1, 22.1% had 2 and 3.9% had 3. Many subjects (42.5%) had ≥1 TI with re-injection at week ≥18.
Conclusions: These results demonstrate variability in the duration of treatment effect, which supports the use of flexible and individualized dosing intervals for the treatment of ULPSS. The duration of treatment effect was ≥14 weeks after most treatments; however, a considerable proportion of patients experienced effects lasting up to 20 weeks.