Responsiveness of the Scripps neurologic rating scale during a multiple sclerosis clinical trial

Objective: The Scripps neurologic rating scale (SNRS) is a summary measure of individual components comprising a neurological examination, designed for use in multiple sclerosis (MS). Our objective is to evaluate the responsiveness of the SNRS, within the context of a 2-year, randomized, double-blind crossover study of the efficacy of cladribine for treatment of secondary progressive MS. Methods: Effect sizes were determined for the SNRS and its components, separately for each treatment group (initial placebo, and initial cladribine) over both years of the clinical trial, using a standard random effects model. Results: Individual components tended to show positive effect sizes (improvement) during periods of active therapy in both treatment groups, and negative effect sizes (deterioration) during periods of no active therapy. Summation indices derived from the individual components of the SNRS seemed somewhat more stable than the individual components. The two components mentation and mood, and bladder, bowel, or sexual dysfunction, were rather unresponsive in our clinical trial. Conclusions: Changes in the components of the SNRS over the course of our clinical trial were consistent between the two treatment groups. Most components were moderately responsive; and, the summary SNRS score appropriately summarized the moderate magnitudes of change evinced in the individual components.