Subclinical MRI Activity Independently Predicts PIRA, SPMS, and Disability Worsening in MS
KEY TAKEAWAYS
- MRI activity without clinical relapses was independently associated with higher odds of conversion to secondary progressive MS (SPMS), PIRA, and confirmed disability worsening (CDW).
- For PIRA, only MRI-only activity predicted risk. Relapse-only and combined activity did not.
- The findings support routine MRI monitoring in patients with MS who appear clinically stable.
In patients with relapsing-remitting MS (RRMS), new MRI activity without relapses may be an early warning of disability progression. That finding comes from an MSBase registry analysis presented at MSToronto2026.
How Was the Study Designed?
Researchers analyzed 19,262 patients with RRMS in the MSBase registry who had at least 5 years of follow-up and at least 2 subsequent MRI examinations. Patients were grouped by inflammatory activity during the 5 years before an index date: no activity, MRI-only, relapse-only, or combined. Entropy balancing was used to balance covariates across groups, and weighted logistic and Cox models were fitted for each outcome.
What Did the Researchers Find?
Overall, 7,167 patients (37.2%) met criteria for SPMS conversion, 5,921 (30.7%) for PIRA, and 8,477 (44.0%) for CDW.
- SPMS conversion: All 3 active groups had higher odds: MRI-only (OR, 1.15; 95% CI, 1.03-1.29), relapse-only (OR, 1.33; 95% CI, 1.23-1.45), and combined (OR, 1.47; 95% CI, 1.34-1.61).
- PIRA: MRI-only activity was independently associated (OR, 1.15; 95% CI, 1.02-1.29), but relapse-only and combined activity were not.
- CDW: All 3 active groups were associated (OR range, 1.19-1.33).
Time-to-event analyses pointed in the same direction across all outcomes.
What Does This Mean for MRI Monitoring?
The authors concluded that subclinical MRI activity predicts progression regardless of relapse burden, with the most distinct pattern seen for PIRA. Their results suggest that MRI surveillance does more than detect breakthrough inflammatory disease. Serial imaging, paired with careful longitudinal disability assessment, may also help identify patients at risk for relapse-independent progression.
Source
Torres-Mora C, Ontaneda D, Castro-García DE, et al; MSBase Study Group. Subclinical MRI activity independently predicts the development of SPMS, PIRA, and confirmed disability worsening in multiple sclerosis. Abstract 0083. Presented at: MSToronto 2026, the 10th Joint ACTRIMS-ECTRIMS Meeting; October 21-23, 2026; Toronto, Ontario, Canada.