Objective Assess the predictive value of cognitive processing speed (CPS), using the Symbol Digit Modali- ties Test (SDMT) score, on disability progression in secondary progressive multiple sclerosis (SPMS).

Design/Methods SPMS patients from the Phase 3 EXPAND study (core part [CP] and core+extension part [CP+EP]) were categorised into quartiles of baseline SDMT score (worst-WQ [Q1], intermediate [Q2-Q3], and best-BQ [Q4] quartile). The predictive value of baseline SDMT quartiles for time-to-wheelchair (T2W; i.e., Expanded Disability Status Scale [EDSS] score ≥7) sustained until end of follow-up, or 6-month confirmed disability progression (6mCDP) by EDSS, were assessed at the end of the CP (up to 37-months) and CP+EP (up to 5-years) by Cox regression (adjusted for treatment, age, gender, baseline EDSS, baseline SDMT quartile, and treatment-by-baseline SDMT quartile interaction).

Results Analyses included 1628/1651 patients (98.6%) randomised in EXPAND (baseline SDMT: WQ, n=435; intermediate, n=808; BQ, n=385). Risk of T2W (WQ vs BQ) was higher in the CP (HRWQ/BQ=1.31, 95% CI:0.72–2.38; p=0.37) and increased with long-term follow-up (HRWQ/BQ=1.81; 1.17–2.78; p=0.01). Baseline SDMT was not predictive of 6mCDP. The predictive value of on-study SDMT score change will be presented.

Conclusions The results support the predictive value of CPS for long-term physical disability progression in SPMS. Funding: Novartis Pharma AG, Basel, Switzerland.