Poster 350 A Random Effect Mixed Treatment Comparison (MTC) to Compare the Efficacy of Botulinum Toxin Type A Treatments for Cervical Dystonia

Objectives: This research was conducted to provide a systematic pairwise comparison of all available botulinum toxin type A treatments for cervical dystonia (CD) as there is a lack of direct head to head clinical trial data evidence. Three botulinum toxin type A products have been approved by the FDA for managing CD: AbobotulinumtoxinA, OnabotulinumtoxinA and IncobotulinumtoxinA. A pair-wise efficacy comparison was performed for all three toxins based on literature-reported clinical outcomes. Methods: Multi-armed randomized controlled trials (RCTs) for inclusion were identified using a systematic literature review. RCTs were assessed for comparability based on patient population and comparable efficacy outcome measures. The Toronto Western Spasmodic Torticollis Rating Scale (TWSTRS) total score was selected as the efficacy outcome measurement for assessment. A mixed treatment comparison (MTC) was conducted using a Bayesian hierarchical model allowing indirect comparison of the efficacies of the interventions. Results: The network of six RCTs with fourteen arms formed a linear series of "steps" which facilitated the comparison of all botulinum toxin type A treatments of interest. Due to the limitation of available clinical data, this study only investigated the main effect of toxin treatments without explicitly considering potential confounding factors such as gender and formulation differences. There was reasonable agreement between the number of unconstrained data points, residual deviance and pair-wise results, suggesting a coherent network. The results for TWSTRS total scale change from baseline for all treatments were: Placebo (mean -4.487, SE 1.402), AbobotulinumtoxinA (mean -11.08, SE 1.41), OnabotulinumtoxinA (mean -11.77, SE 1.44) and IncobotulinumtoxinA (mean -12.38, SE 1.79); where a negative number indicates symptom improvement. Conclusions: This research suggests that all botulinum toxin type A treatments were effective compared to placebo in cervical dystonia. However, based on this MTC analysis, there is no significant efficacy difference between AbobotulinumtoxinA, OnabotulinumtoxinA and IncobotulinumtoxinA.