The role of age in choosing high-efficacy treatment for multiple sclerosis - an Austrian MS Database study

Background: Treatment strategy for relapsing multiple sclerosis (RMS) is increasingly shifting towards first-line use of high-efficacy DMT (H-DMT). However, DMT efficacy declines with increasing age and the benefit of first line H-DMT at higher age remains unclear. Here, we aimed to investigate whether the superiority of H-DMT over moderate-efficacy DMT (M-DMT) depends on age. Methods: Using the Austrian MS database, we included previously DMT-naive RMS patients aged >18 years, who i) initiated a DMT continuing it for >12 months, ii) had MRI at baseline, and iii) had clinical follow-up for >24 months. Cox regression analyses including age and DMT strategy (H-DMT vs. M-DMT) plus an interaction effect were employed to predict time to re-lapse. Results: A total of 215 RMS patients (median age of 41 years [25th-75th percentiles: 32-53], 66% females) were observed over a median of 42 (28-58) months. During this period, eighty-one (38%) patients had a relapse. While increasing age was associated with decreased risk of re-lapse (hazard ratio (HR) 0.95 per year, 95% confidence interval [CI]: 0.93-0.98, p<0.001), the use of H-DMT lowered the risk of relapse compared to M-DMT (HR 0.06, 95%-CI: 0.01-0.45, p=0.007). In patients with H-DMT, the benefit of treatment was reduced by increasing age (HR: 1.06, 95%-CI: 1.01-1.11, per year, p=0.031). Superiority of H-DMT over M-DMT was esti-mated to be lost at the age of approximately 50 years. Conclusion: The benefit of H-DMT over M-DMT as first-line treatment decreases with in-creasing age and seems to vanish in patients above approximately 50 years.