Table 5.

Study-level variables to consider in comparing efficacy and duration of different BoNTs.

Patient population	Are there differences in clinical presentation, severity, or duration of disease, or of pre-existing conditions/comorbidities? Is a more or less responsive group included or excluded? Disease severity/complexity may influence overall efficacy, which can influence efficacy and duration.
Doses	Does the study account for dose–response effects in comparing products, in addition to non-interchangeability of units when evaluating efficacy and duration? Higher doses may lead to increased efficacy and longer durations.
Injection paradigm	Are the muscles and injection sites optimized for each of the BoNT products?
Efficacy and duration assessments	Are the definitions of efficacy and duration the same/comparable for the different products? For example, a definition that requires two raters to agree on an outcome is more difficult to achieve and will lead to longer duration than that of a single rater.
Rating scales/raters	Are the same rating scales being used? Who is doing the rating (e.g., investigator, subject)? Different scales and raters may yield different apparent responder rates and durations. Patient perception is an important outcome.
Follow-up timepoints	Is the number of timepoints adequate to provide a full assessment of duration? More follow-up timepoints give a more precise estimate of duration.