Abstract
BACKGROUND: Treatment strategy for relapsing multiple sclerosis (RMS) is increasingly shifting toward first-line use of high-efficacy DMT (H-DMT). However, differences in DMT efficacy appear to decline with increasing age, and the benefit of first-line H-DMT at higher age currently remains unclear. The aim of this study was to investigate whether the superiority of H-DMT over moderate-efficacy DMT (M-DMT) decreases with age. METHODS: Using the Austrian MS database, we included previously DMT-naïve 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 relapse. RESULTS: A total of 215 RMS patients (median age of 41 years [25(th)-75(th) 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 higher age was associated with decreased risk of relapse (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 per year, 95%-CI 1.01-1.11, p = 0.031). Superiority of H-DMT over M-DMT was not detectable above the age of 52 years. CONCLUSION: Efficacy of H-DMT as first-line treatment decreases with increasing age and approximates efficacy of M-DMT above 50 years.