Dimethyl fumarate (DMF) clinical trials excluded relapsing-remitting multiple sclerosis (RRMS) patients aged >55 years (yrs). The limited data on DMF use in this age group evaluated relapses but not disability. Unlike relapses, which often decrease as MS patients age, disability progression often increases.
To characterize long-term disability outcomes over 4.5 yrs of DMF treatment in RRMS participants based on age at time of DMF initiation.
We identified NARCOMS participants (pts) with RRMS, living in the US, and initiating DMF from Fall 2013–Spring 2018 with ≥1 yr follow-up. We dichotomized age at DMF initiation as <55 (younger) and ≥55 yrs (older). Disability was measured using the Patient Determined Disease Steps (PDDS). Time to 6-month confirmed PDDS progression (≥1-point increase) and conversion to SPMS were estimated using the Kaplan-Meier method and compared using a log rank test. Cox proportional hazards regression models were adjusted for sex and initial PDDS level. Pts were censored at last follow-up or DMF discontinuation, whichever came first. Safety data were not collected.
647 RRMS pts initiated DMF. In the younger subgroup (n=351, 54%), median age was 47 yrs, 88% female, and 24% reported a relapse in the last 6 months. In the older subgroup (n=296, 46%), median age was 60 yrs, 82% female, and 22% reported a relapse in the last 6 months. Compared to the younger subgroup, older pts had longer MS disease duration (11 vs 17 yrs, p<0.001) and significantly greater disability at baseline as measured by PDDS. Median treatment duration was 2.5 yrs in younger pts and 2 yrs in older pts. At last follow-up, 283 (81%) younger pts and 236 (80%) older pts remained on DMF. Most pts in both groups were estimated to remain free of disability progression over 4.5 yrs: 64% (95%CI: 57-71) of younger pts vs 74% (95%CI: 67-80) of older pts (p=0.12). Most pts in both subgroups also were estimated to remain free from conversion to SPMS over 4.5 yrs: 90% (95%CI: 85-94) of younger pts vs 86% (95%CI: 79-91) of older pts (p=0.17).
Conclusions: As expected, older pts (≥55 yrs) had significantly longer MS disease duration and higher baseline disability compared with younger pts (<55 yrs). Despite these baseline differences, most pts in both groups remained free of PDDS progression and free from conversion to SPMS over 4.5 yrs of DMF treatment.
Supported by: Biogen; NARCOMS is a project of the CMSC