Figure 3. Long-term Outcomes: Progression Independent of Relapse Activity (PIRA) vs Relapse-Associated Worsening (RAW) Comparison.

A, Crude description of nonconfirmed Expanded Disability Status Scale (EDSS) score changes between baseline EDSS and last clinical visit, for patients with PIRA, RAW, and no confirmed disability accumulation (CDA). Patients with PIRA and RAW seem to be associated with a much heavier disability burden than patients without CDA, even in this unadjusted picture. When comparing PIRA and RAW, PIRA seems to be associated with greater increases in EDSS score than RAW. These findings were then confirmed through survival models of time to EDSS 6.0 (B). B, Kaplan-Meier curves of time to EDSS 6.0 from the first demyelinating attack, for patients with PIRA, RAW, and without CDA. All 3 survival curves were very different (log-rank test, χ²₂ = 44.11; P <.001). Patients with PIRA showed significantly faster rates of reaching EDSS 6.0 than patients with RAW (log-rank test, χ²₁ = 4.88; P <.03).