Progression independent of relapse activity and risk of long-term disability in multiple sclerosis

Progression independent of relapse activity (PIRA) was found to be associated with greater expanded disability status scale (EDSS) increases (P<0.001) and 8-fold greater chance of reaching EDSS 6.0 (P=0.001).
Experience of PIRA earlier in the disease course was associated with greater EDSS increases (P<0.001) and a 26-fold greater chance of reaching EDSS 6.0 (P=0.009) than PIRA later in the disease course (P<0.001).
The authors concluded that PIRA following the first demyelinating event in multiple sclerosis is associated with poorer outcomes, an unpromising clinical diagnosis especially if PIRA occurs early in the disease course. Further research into prevention or slowing of PIRA may be needed to improve clinical outcomes for affected individuals.