OBJECTIVES

: The Multiple Sclerosis Impact Scale (MSIS) -29 is a measure of the impact of multiple sclerosis (MS) from the patient’s perspective and scores range from 0-100 (higher scores indicating poor health). The objective of this study was to evaluate the responder definition (RD) for the MSIS-29, v2 (both physical [PHYS] and psychological scale [PSYCH]) in patients with secondary progressive multiple sclerosis (SPMS) participating in a clinical trial.

METHODS

: Data used in the analyses come from the EXPAND trial which evaluated the efficacy and safety of siponimod in patients with SPMS. Anchor- and distribution-based approaches were used to estimate the RD for MSIS-29, v2. The anchor-based approach compared the change in MSIS-29, v2 with other measures of change, which served as the anchors. Three anchors were considered - Expanded Disability Status Scale (EDSS), Multiple Sclerosis Walking Scale (MSWS-12), and 9-Hole Peg Test (9-HPT) – in two analytical strategies: 1) receiver operating characteristic curve analyses; 2) mean change in pre-defined anchor-based change categories. Distribution-based results were based on the minimal detectable change.

RESULTS

: Of the three proposed anchors, MSWS-12 was the only anchor for which Spearman correlations were consistently above 0.3. Using MSWS-12, the anchor-based approach resulted in RD estimates for deterioration ranging between 3 and 10 for PHYS, and between 3 and 7 for PSYCH. RD estimates for improvement ranged from -8 to -4 for PHYS, and from -7 to -4 for PSYCH. Distribution-based RD estimates ranged between 6.8 and 8.2 for PHYS and between 7.6 and 9.1 for PSYCH.

CONCLUSIONS

: The results indicate that thresholds of approximately 8 and 7 points should be recommended, as RD estimates for PHYS and PSYCH scales of the MSIS-29, v2, respectively. Estimates are similar to the RD of 7.5 for deterioration previously established for the MSIS-29, v1, among patients with relapsing–remitting multiple sclerosis.