Contribution of Relapse-Independent Progression vs Relapse-Associated Worsening to Overall Confirmed Disability Accumulation in Typical Relapsing Multiple Sclerosis in a Pooled Analysis of 2 Randomized Clinical Trials

Accumulation of disability in multiple sclerosis may occur as relapse-associated worsening (RAW) or steady progression independent of relapse activity (PIRA), with PIRA regarded as a feature of primary and secondary progressive multiple sclerosis.

To investigate the contributions of relapse-associated worsening vs relapse-independent progression to overall confirmed disability accumulation (CDA) and assess respective baseline prognostic factors and outcomes of 2 treatments. Design, Setting, and Participants: Analyses occurred from July 2015 to February 2020 on pooled data from the intention-to-treat population of 2 identical, phase 3, multicenter, double-blind, double-dummy, parallel-group randomized clinical trials (OPERA I and II) conducted between August 2011 and April 2015. In the trials, patients with relapsing multiple sclerosis (RMS), diagnosed using the 2010 revised McDonald criteria, were randomized from 307 trial sites in 56 countries; resulting data were analyzed in the pooled data set. Interventions: Participants were randomized 1:1 to receive 600 mg of ocrelizumab by intravenous infusion every 24 weeks or subcutaneous interferon β-1a 3 times a week at a dose of 44 μg throughout a 96-week treatment period. Main Outcomes and Measures: Confirmed disability accumulation was defined by an increase in 1 or more of 3 measures (Expanded Disability Status Scale, timed 25-ft walk, or 9-hole peg test), confirmed after 3 or 6 months, and classified per temporal association with confirmed clinical relapses (PIRA or RAW).