Abstracts from the ASENT 2008 Annual Meeting March 6–8, 2008

Background and Objective An assessment of clinically important change is useful in interpreting clinical trial outcomes. The 4-point Ashworth Scale (AS) is a widely accepted measure of muscle tone, and the 9-point Physician Global Assessment Score (PGAS) is a global measure of post-treatment change as evaluated by the physician. The quantitative relationship between AS and PGAS has not previously been described in spasticity. Methods Data from three clinical trials of botulinum toxin type A (BOTOX; Allergan, Irvine, CA) in poststroke spasticity were analyzed ( n = 442). Mean change from baseline in AS score was plotted as a function of PGAS and correlations were calculated. Receiver–operator curve (ROC) analyses with the wrist flexor AS change from baseline as the independent variable and PGAS as the dependent variable were performed using the following criteria: PGAS of ≥1 (mild improvement or better) and PGAS of ≥2 (moderate improvement or better). Results In pooled data, the Pearson's correlation coefficient r between the change in wrist Ashworth Score and the PGAS was −0.44 ( p = 0, t = −26.5). Pearson correlations by individual study were also statistically significant. By ROC analysis, a PGAS of ≥1 was associated with 33% reduction of wrist AS and a PGAS of ≥2 was associated with approximately 50% reduction. In a well-powered phase 3 study, the Pearson's correlation coefficient was even higher ( r = −0.76, p = 0, t = −28.5). Conclusions Changes in disease-specific scales that correlate significantly with changes in physician global assessments are considered clinically meaningful. In clinical trials of chronic spasticity, we found that 33% and 50% changes in the Ashworth Scale scores correlate with 1-point or 2-point changes in PGAS. This is similar to findings from pooled chronic pain studies, in which 30% and 50% changes on the pain numeric rating scale were considered clinically important (Farrar et al., Pain 2001;94:149–158). Study supported by Allergan, Irvine, CA.