Progression independent of relapse and MRI activity and treatment strategies in multiple sclerosis.

The impact of high-efficacy therapies (HET) on progression independent of relapse and MRI activity (PIRMA) remains poorly defined. In this context, using the French MS registry, we aimed to assess the real-life effectiveness of HET compared with moderate-efficacy therapies (MET) on PIRMA in patients with relapsing-onset multiple sclerosis. Data were collected from patients with relapsing-onset multiple sclerosis of the French MS registry, between January 2010 and June 2023, with a mean follow-up of 3.7 years. Patients with relapsing-onset multiple sclerosis were included in the analysis if they were treated first with HET (2666 included) or MET (7833 included) and had expanded disability status scale and MRI follow-up every 2 years. Each outcome was studied using a propensity score framework. The primary outcome was time to first PIRMA. Secondary outcomes were PIRMA incidence, time to first confirmed disability progression, relapse-associated worsening (RAW), MRI-associated worsening (MAW) and identification of risk factors associated with PIRMA. A total of 10 499 patients fulfilled the inclusion criteria. The mean and standard deviation (SD) age at treatment initiation was 36.4 (10.3) years, with a mean (SD) disease duration of 3.1 (5.1) years. The restricted mean (SD) survival time to first PIRMA was slightly, but significantly shorter in the HET group compared with the MET group [8.7 (0.08) versus 8.9 (0.05) years, P = 0.017]. However, when looking at time to first confirmed disability progression, it tend to be longer in the HET group compared with the MET group [7.6 (0.10) versus 7.3 (0.06) years, P = 0.071], and it was probably linked to the shorter time to first RAW and MAW in the MET group [9.2 (0.06) versus 8.7 (0.05) years, P < 0.001 for RAW; and 9.0 (0.05) versus 8.5 (0.07) years, P < 0.001 for MAW]. Baseline risk factors associated with increased PIRMA incidence in the whole population were high expanded disability status scale, higher age at baseline and the presence of spinal cord lesions. Even if HET gives better control on disability accumulation related to disease activity than MET, our real-life study suggests that PIRMA-related mechanisms are not differentially affected by HET versus MET.