OBJECTIVES: Multiple sclerosis (MS) disease progression is measured by the Expanded Disability Status Scale (EDSS). UK MS clinical guidelinesrecommend that patients discontinue treatment with disease modifying therapies (DMTs) on reaching EDSS ≥7.0, or experiencing non-relapsing secondary progressive MS (SPMS).  This study derived the time for patients to reach EDSS ≥7.0 or SPMS from EDSS 4.0 or 5.0, for patients treated with delayed-release dimethyl fumarate 240mg (DMF; also known as gastro-resistant DMF), or no DMT treatment. METHODS: The time taken to reach relapsing-remitting MS (RRMS) EDSS ≥7.0, or SPMS (any EDSS state) from EDSS 4.0 or 5.0 was estimated from transition probability matrices using algebraic techniques from Mandel 2007: the time to EDSS ≥7.0 or SPMS was derived for each matrix (DMF, untreated) by using matrix multiplication to estimate the proportion of patients who had reached these states over time.  The transition matrix for untreated patients was derived using placebo arm data from clinical trials(for RRMS population) and London Ontario dataset (for transitions from RRMS to SPMS). The transition matrix for DMF was estimated by applying treatment effect on disability progression (sourced from a mixed treatment comparison), to the probability of progressing in the untreated matrix. Probabilistic sensitivity analysis was conducted to estimate 95% confidence intervals (CIs).  RESULTS: The time for progression from EDSS 4.0 to ≥7.0 or SPMS was 8.53 years (95% CI: 7.05-10.25) for patients treated with DMF and 5.90 years (95% CI: 5.59-6.24) for untreated patients. The time from EDSS 5.0 to ≥7.0 or SPMS was 5.28 years (95% CI: 4.32-6.37) for patients treated with DMF and 3.64 years (95% CI: 3.34-3.96) for untreated patients. CONCLUSIONS: Our analysis showed that DMF therapy was associated with a longer time interval between EDSS 4.0 or 5.0 and progression to EDSS ≥7.0 or SPMS relative to no DMT treatment.