Risk factors and importance of persistent PIRA

In a cohort study, sustained progression independent of relapse activity (PIRA) was found to increase the risk of severe disability and secondary progressive MS (SPMS) by a factor of 4 or 5. However, PIRA is not the same as early SPMS, as one-third of patients with relapsing-remitting MS showed a confirmed improvement in the Expanded Disability Status Scale (EDSS) score after PIRA.

Dr Chao Zhu (Monash University, Australia) and colleagues studied the risk factors associated with persistence or improvement after PIRA, as well as the effects of PIRA persistence on long-term outcomes in MS [1]. PIRA can be a sign of early SPMS, but PIRA events may regress over time. A cohort study was set up using data from 4,713 patients with relapsing-remitting MS, who were enrolled in the MSBase registry between April 1995 and January 2024. One of the inclusion criteria was a minimum of 1 PIRA event, defined as 6-month confirmed disability progression (CDP) without relapse. The primary outcome was time to 6-month confirmed improvement after PIRA.

After a median follow-up of 6.8 years, the primary endpoint was met by almost a third of the investigated patients (n=1,507; 32%). When matched with patients with persistent PIRA (n=3,206) in a multivariate analysis, improvement after PIRA was significantly associated with younger age (HR 0.98; 95% CI 0.98–0.99; P<0.0001), lower EDSS at baseline (HR 0.74; 95% CI 0.69–0.78; P<0.0001), and high-efficacy disease-modifying treatment use at baseline (HR 1.22; 95% CI 1.08–1.38; P<0.0015).

Investigated patients with persistent PIRA were at a substantially higher risk of reaching EDSS 6 and SPMS, compared with non-persistent PIRA: the HR was 5.19 (95% CI 4.05–6.67; P<0.0001) for reaching EDSS 6, and 3.51 (95% CI 2.42–5.08; P<0.0001) for reaching SPMS.

1. Zhu C, et al. Risk factors associated with persistent progression independent of relapse activity (PIRA), and the association of persistent PIRA with disability progression in multiple sclerosis. Abstract O055, ECTRIMS 2024, 18–20 September, Copenhagen, Denmark.

 

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Posted on 18 November 202418 November 2024