Most cited article - PubMed ID 34755108
Relapse-independent multiple sclerosis progression under natalizumab
Patients with relapsing-remitting multiple sclerosis (RRMS) may experience disability progression independent of relapse activity (PIRA), which can be an early sign of secondary progressive MS (SPMS). We defined persistent PIRA as ongoing sustained disability over the entire available follow-up period. However, PIRA events can regress over time. Identifying factors that predict PIRA persistence is of great interest as they can refine the definition of RRMS to SPMS transition. Equally, factors associated with the non-persistence of PIRA have potential treatment implications for patients suffering from a PIRA event. We conducted a study to examine risk factors for PIRA persistence and risk differences in long-term disability progression between persistent and non-persistent PIRA. In this cohort study, we included only patients who had already experienced a PIRA event and investigated the persistence of disability progression following their first PIRA event. Therefore, PIRA occurrence time was set as the baseline. Data were collected from the MSBase registry between April 1995 and January 2024, with a median follow-up of 8.7 years. The primary outcome was time to 6-month confirmed non-persistence of PIRA. Secondary outcomes comprised time to 6-month confirmed Expanded Disability Status Scale (EDSS) 6 and time to SPMS. A stratified Cox regression model was used to identify risk factors associated with non-persistent PIRA. We then matched persistent PIRA patients with non-persistent PIRA patients in a 1:1 ratio using propensity scores, and compared their risk of reaching EDSS 6 using the Cox regression model. We re-matched patients with complete Kurtzke Functional Systems Scores to compare their risks of reaching SPMS. We included 4713 RRMS patients with PIRA, of whom around one-third experienced a post-PIRA disability improvement, over a relatively long period (median of 2.6 years to improvement). Use of high-efficacy disease-modifying therapies (DMT) at baseline [hazard ratio, 1.22; 95% confidence interval, (1.08-1.38); P = 0.0015], lower baseline EDSS [hazard ratio, 0.73 (0.69-0.78); P < 0.0001] and younger age [per 10 years; hazard ratio, 0.84 (0.80-0.89); P < 0.0001] were associated with non-persistent PIRA. Patients with non-persistent PIRA had a hazard ratio of 0.19 [95% confidence interval, (0.15-0.25); P < 0.0001] for reaching EDSS 6 and 0.18 [(0.11-0.29); P < 0.0001] for reaching SPMS compared to patients with persistent PIRA. PIRA events slowly regress in one-third of patients. Patients with persistent PIRA had a substantially higher risk of reaching EDSS 6 and SPMS than those with non-persistent PIRA. Younger age, lower baseline EDSS, and use of high-efficacy DMT during PIRA events were associated with PIRA regression.
Multiple sclerosis is a chronic, inflammatory, and neurodegenerative disease of the central nervous system and a major cause of neurological disability in young adults. Its prevalence and incidence are increasing, and it has been estimated at over 2.8 million cases worldwide, in addition to recent trends towards a shift in MS prevalence to older ages, with peak prevalence estimates in the sixth decade of life. Although historically the relapsing and progressive phases of the disease have been considered separate clinical entities, recent evidence of progression independent of relapse activity (PIRA) has led to a reconsideration of multiple sclerosis as a continuum, in which relapsing and progressive features variably coexist from the earliest stages of the disease, challenging the traditional view of the disease course. In this Series article, we provide an overview of how the traditional description of the clinical course of MS and epidemiological trends in Europe have evolved. For this purpose, we focus on the concept of PIRA, discussing its potential as the main mechanism by which patients acquire disability, how its definition varies between studies, and ongoing research in this field. We emphasise the importance of incorporating the assessment of hidden clinical manifestations into patient management to help uncover and quantify the PIRA phenomenon and the possible implications for future changes in the clinical classification of the disease. At the same time, we provide insights into overcoming the challenges of identifying and defining PIRA and adopting a new understanding of the clinical course of MS.
- Keywords
- Clinical classification, Epidemiology, Multiple sclerosis, Progression idependent of relapse activity,
- Publication type
- Journal Article MeSH
- Review MeSH
Many challenges exist in the precise diagnosis and clinical management of secondary progressive multiple sclerosis (SPMS) because of the lack of definitive clinical, imaging, immunologic, or pathologic criteria that demarcate the transition from relapsing-remitting MS to SPMS. This review provides an overview of the diagnostic criteria/definition and the heterogeneity associated with different SPMS patient populations; it also emphasizes the importance of available prospective/retrospective tools to identify patients with SPMS earlier in the disease course so that approved disease-modifying therapies and nonpharmacological strategies will translate into better outcomes. Delivery of such interventions necessitates an evolving patient-clinician dialog within the context of a multidisciplinary team.
