Predictors of Progression Independent of Relapse Activity in Relapsing Remitting Multiple Sclerosis

The goal of this prospective observational cohort study is to determine the frequency of progression independent of relapse activity (PIRA) and identify its clinical, radiological, neuroaxonal, and functional predictors in patients with early relapsing-remitting multiple sclerosis (RRMS). The study aims to facilitate early identification of patients at increased risk of disability progression independent of relapses and to support individualized therapeutic decision-making.

The main questions it aims to answer are:

What is the frequency of PIRA in patients with early RRMS? Which demographic and clinical characteristics are associated with the development of PIRA? Which MRI biomarkers, including lesion burden, brain atrophy, spinal cord involvement, and paramagnetic rim lesions (where available), are associated with PIRA? Can optical coherence tomography (OCT) measurements, including peripapillary retinal nerve fiber layer (pRNFL) and macular ganglion cell-inner plexiform layer (mGCIPL) thickness, predict PIRA? Are serum biomarkers, including neurofilament light chain (NfL) and glial fibrillary acidic protein (GFAP), associated with an increased risk of PIRA? Which baseline factors independently predict disability progression?

Participants will undergo comprehensive baseline and follow-up assessments, including collection of demographic and clinical data, neurological examination with Expanded Disability Status Scale (EDSS) scoring, brain and spinal cord MRI, OCT assessment, laboratory evaluation of serum biomarkers (where available), and validated functional and patient-reported outcome measures. Participants will be followed longitudinally to identify confirmed disability accumulation (CDA) and classify disability progression as PIRA or relapse-associated worsening (RAW).

The primary outcome is the occurrence of PIRA, defined as confirmed disability accumulation independent of clinical relapses during follow-up. Secondary outcomes include identification of independent clinical, imaging, OCT, and laboratory predictors of PIRA and evaluation of their association with long-term disability progression. The findings may improve early risk stratification and support timely initiation of high-efficacy disease-modifying therapies in patients with early RRMS.