Disease-modifying Drugs For Multiple Sclerosis Research Articles

Adverse Events Associated With Disease-Modifying Drugs for Multiple Sclerosis: A Multiregional Population-Based Study

It is not possible to fully establish the safety of a disease-modifying drug (DMD) for multiple sclerosis (MS) from randomized controlled trials as only very common adverse events occurring over the short-term can be captured, and the quality of reporting has been variable. We examined the relationship between the DMDs for MS and potential adverse events in a multiregion population-based study. We identified people with MS using linked administrative health data from 4 Canadian provinces. MS cases were followed from the most recent of first MS or related demyelinating disease event on January 1, 1996, until the earliest of emigration, death, or December 31, 2017. DMD exposure primarily comprised β-interferon, glatiramer acetate, natalizumab, fingolimod, dimethyl fumarate, teriflunomide, and alemtuzumab. We examined associations between DMD exposure and infection-related hospitalizations and physician visits using recurrent events proportional means models and between DMD exposure and 15 broad categories of incident adverse events using stratified multivariate Cox proportional hazard models. We identified 35,894 people with MS. While virtually all DMDs were associated with a 42%-61% lower risk of infection-related hospitalizations, there was a modest increase in infection-related physician visits by 10%-33% for select DMDs. For incident adverse events, most elevated risks involved a second-generation DMD, with alemtuzumab's hazard of thyroid disorders being 19.42 (95% CI 9.29-36.51), hypertension 4.96 (95% CI 1.78-13.84), and cardiovascular disease 3.72 (95% CI 2.12-6.53). Natalizumab's highest risk was for cardiovascular disease (adjusted hazard ratio [aHR] 1.61; 95% CI 1.24-2.10). For the oral DMDs, fingolimod was associated with higher hazards of cerebrovascular (aHR 2.04; 95% CI 1.27-3.30) and ischemic heart diseases (aHR 1.64; 95% CI 1.10-2.44) and hypertension (aHR 1.73; 95% CI 1.30-2.31); teriflunomide with higher hazards of thyroid disorders (aHR 2.30; 95% CI 1.11-4.74), chronic liver disease (aHR 1.94; 95% CI 1.19-3.18), hypertension (aHR 1.76; 95% CI 1.32-2.37), and hyperlipidemia (aHR 1.61; 95% CI 1.07-2.44); and from complementary analyses (in 1 province), dimethyl fumarate with acute liver injury (aHR 6.55; 95% CI 1.96-21.87). Our study provides an extensive safety profile of several different DMDs used to treat MS in the real-world setting. Our findings not only complement those observed in short-term clinical trials but also provide new insights that help inform the risk-benefit profile of the DMDs used to treat MS in clinical practice. The results of this study highlight the continued need for long-term, independent safety studies of the DMDs used to treat MS. This study provides Class III evidence that for patients with MS, while DMD exposure reduces the risk of infection-related hospitalizations, there are increased risks of infection-related physician visits and incident adverse events for select DMDs.

Multiple sclerosis disease-modifying drug use by immigrants: a real-world study

Little is known about disease-modifying drug (DMD) initiation by immigrants with multiple sclerosis (MS) in countries with universal health coverage. We assessed the association between immigration status and DMD use within 5-years after the first MS-related healthcare encounter. Using health administrative data, we identified MS cases in British Columbia (BC), Canada. The index date was the first MS-related healthcare encounter (MS/demyelinating disease-related diagnosis or DMD prescription filled), and ranged from 01/January/1996 to 31/December/2012. Those included were ≥ 18 years old, BC residents for ≥ 1-year pre- and ≥ 5-years post-index date. Persons becoming permanent residents 1985–2012 were defined as immigrants, all others were long-term residents. The association between immigration status and any DMD prescription filled within 5-years post-index date (with the latest study end date being 31/December/2017) was assessed using logistic regression, reported as adjusted odds ratios (aORs) with 95% confidence intervals (CIs). We identified 8762 MS cases (522 were immigrants). Among immigrants of lower SES, odds of filling any DMD prescription were reduced, whereas they did not differ between immigrants and long-term residents across SES quintiles (aOR 0.96; 95%CI 0.78–1.19). Overall use (odds) of a first DMD within 5 years after the first MS-related encounter was associated with immigration status.

Impact of adherence to disease-modifying drugs in multiple sclerosis: A study on Italian real-world data

BackgroundMultiple Sclerosis (MS) is a chronic inflammatory disease of the central nervous system requiring complex diagnostic and therapeutic management. Treatment with Disease Modifying Drugs (DMDs) is aimed at reducing relapse rate and disease disability. Few real-world, population-based data are available on the impact of adherence on relapse rate.The objective of this study was to assess the impact of adherence to DMDs on relapses in a real-world Italian setting. MethodsPopulation-based cohort study. People with MS (PwMS) older than 18 years and residing in the Emilia-Romagna region, Northern Italy, were identified through administrative databases using a validated algorithm. A Cox regression model with a time-varying exposure was performed to assess the association between level of adherence to DMDs and relapses over a 5-year period. ResultsA total of 2,528 PwMS receiving a first prescription of DMDs between 2015 and 2019 were included (average age of 42, two-thirds female). Highly adherent PwMS had a 25 % lower hazard of experiencing moderate or severe relapses than non-adherent PwMS (Hazard Ratio 0.75, 95 % CI 0.58 to 0.98), after adjusting for age and sex. Several sensitivity analyses supported the main result. ConclusionThe results of our study support the hypothesis that a high level of DMD adherence in MS is associated with a lower risk of moderate or severe relapse. Therefore, choosing the DMD with which to start drug treatment and recommending adherence to treatment appear to be crucial aspects involving both physicians and patients.

Clinical factors and response to therapy with disease-modifying drugs for multiple sclerosis: the experience of the Tomsk region

To investigate a disease-modifying drugs (DMD) response in multiple sclerosis (MS) in the Tomsk region population and detect clinical factors associated with the treatment response. A 5-year prospective clinical study included 363 MS patients of the Tomsk region taking DMDs of the «first-line» and «second-line treatments». The response to DMDs therapy and the impact of MS clinical characteristics on response to treatment were assessed. Clinical factors associated with resistance to DMD are male gender, partial reduce of the MS onset symptoms, short period of the first remission, severe neurological impairment, high relapse rate and disease progression rate. Clinical features of MS are crucial factors associated with DMD response and should be used to prescribe DMD. This factor assessment can improve efficacy of the personalized MS treatment.

Repurposing multiples sclerosis disease-modifying drugs for Parkinson's disease

Parkinson’s disease (PD) is an age-related neurodegenerative disease mainly affecting the elderly population. Despite recent progresses in pharmacologic therapies and surgical interventions such as deep brain stimulation, current PD therapies are limited to relieving disease symptoms rather than stopping disease progression, highlighting an urgent yet unmet need for disease-modifying interventions. Neuroinflammation has been proposed as a pivotal contributing factor that drives the initiation and progression of PD pathology. Owing to the revolution in disease-modifying drugs (DMDs) that successfully change the course of multiple sclerosis (MS), a central nervous system inflammatory autoimmune disease, it has become tempting to repurpose MS DMDs as new treatment options for PD. This review summarizes the ongoing and completed studies of MS DMDs in PD as a potential opportunity to address this unmet need. Future clinical trials are warranted to further evaluate the efficacy of DMDs in patients with PD.

Progressive Multifocal Leukoencephalopathy: An Overview of Current Topics

Here, an overview of progressive multifocal leukoencephalopathy (PML) and its drug associations, especially the disease-modifying drug (DMD)-associated PML for multiple sclerosis (MS) were discussed. Additionally, along with presenting the current status of PML in MS caused by natalizumab, fingolimod, and dimethyl fumarate, the possibility of PML onset with siponimod and ofatumumab, the two newly proposed DMDs for MS, was provided. PML treatment in the era of DMD-associated PML, especially PML in MS, is an important issue. With respect to the treatment of PML, to date, there are no specific antiviral drugs against the JC virus; some drugs, that may have therapeutic potential reported recently, were also mentioned.

Disease-Modifying Drugs for Multiple Sclerosis and Association With Survival

Background and ObjectivesWe examined the association between the disease-modifying drugs (DMDs) for multiple sclerosis (MS) and survival in a multiregion population-based study.MethodsWe accessed multiple administrative health databases from 4 Canadian provinces. Persons with MS were identified and followed from the most recent of the first MS or demyelinating event or January 1, 1996 (index date), until death, emigration, or December 31, 2017. Association between the first-generation and second-generation DMDs and all-cause mortality was examined using stratified Cox proportional hazard models, reported as adjusted hazard ratios (aHRs). Timing of DMD initiation was explored, with findings reported at 2, 5, or 10 years postindex date, representing very early, early, or late initiation.ResultsWe identified 35,894 persons with MS; 72% were female. The mean age at index date was 44.5 years (SD = 13.6). The total person-years of follow-up while DMD-exposed was 89,180, and total person-years while unexposed was 342,217. Compared with no exposure, exposure to any DMD or to any first-generation DMD was associated with a 26% lower hazard of mortality (both aHRs 0.74; 95% CI 0.56–0.98), while any second-generation DMD exposure was associated with a 33% lower hazard (aHR 0.67; 95% CI 0.46–0.98). Earlier DMD initiation (beta-interferon or glatiramer acetate vs no exposure) was associated with a significant mortality effect (p < 0.05), while later initiation was not (95% CIs included 1). However, the survival advantage with earlier initiation diminished over time, no longer reaching statistical significance at 15 years postindex date.DiscussionOur study demonstrates an association between the DMDs for MS and improved survival in the real-world setting.

Cladribine Treatment for MS Preserves the Differentiative Capacity of Subsequently Generated Monocytes, Whereas Its Administration In Vitro Acutely Influences Monocyte Differentiation but Not Microglial Activation.

Cladribine (2-chlorodeoxyadenosine, 2CdA) is one of the most effective disease-modifying drugs for multiple sclerosis (MS). Cladribine is a synthetic purine nucleoside analog that induces cell death of lymphocytes and oral cladribine treatment leads to a long-lasting disease stabilization, potentially attributable to immune reconstitution. In addition to its effects on lymphocytes, cladribine has been shown to have immunomodulatory effects on innate immune cells, including dendritic cells and monocytes, which could also contribute to its therapeutic efficacy. However, whether cladribine can modulate human macrophage/microglial activation or monocyte differentiation is currently unknown. The aim of this study was to determine the immunomodulatory effects of cladribine upon monocytes, monocyte-derived macrophages (MDMs) and microglia. We analyzed the phenotype and differentiation of monocytes from MS patients receiving their first course of oral cladribine both before and three weeks after the start of treatment. Flow cytometric analysis of monocytes from MS patients undergoing cladribine treatment revealed that the number and composition of CD14/CD16 monocyte subsets remained unchanged after treatment. Furthermore, after differentiation with M-CSF, such MDMs from treated MS patients showed no difference in gene expression of the inflammatory markers compared to baseline. We further investigated the direct effects of cladribine in vitro using human adult primary MDMs and microglia. GM-CSF-derived MDMs were more sensitive to cell death than M-CSF-derived MDMs. In addition, MDMs treated with cladribine showed increased expression of costimulatory molecules CD80 and CD40, as well as expression of anti-inflammatory, pro-trophic genes IL10 and MERTK, depending on the differentiation condition. Cladribine treatment in vitro did not modulate the expression of activation markers in human microglia. Our study shows that cladribine treatment in vitro affects the differentiation of monocytes into macrophages by modulating the expression of activation markers, which might occur similarly in tissue after their infiltration in the CNS during MS.

Therapeutic Strategy for Multiple Sclerosis Resistant to Standard Treatment: Refractory MS

In Japan, disease-modifying drugs for multiple sclerosis have amounted to eight, to date, providing us with various therapeutic choices. However, we still encounter difficult cases resistant to these drugs. This review summarizes the diagnostic and therapeutic strategies for refractory multiple sclerosis by presenting suggestive cases.

Multiple Sclerosis and Microbiome.

The composition of microbiota and the gut-brain axis is increasingly considered a factor in the development of various pathological conditions. The etiology of multiple sclerosis (MS), a chronic autoimmune disease affecting the CNS, is complex and interactions within the gut-brain axis may be relevant in the development and the course of MS. In this article, we focus on the relationship between gut microbiota and the pathophysiology of MS. We review the contribution of germ-free mouse studies to our understanding of MS pathology and its implications for treatment strategies to modulate the microbiome in MS. This summary highlights the need for a better understanding of the role of the microbiota in patients’ responses to disease-modifying drugs in MS and disease activity overall.

The QOSMOS Study: Pharmacist-Led Multicentered Observational Study on Quality of Life in Multiple Sclerosis.

Health-related quality of life is frequently included in patient-reported outcomes aimed at evaluating the effectiveness of disease-modifying drugs for multiple sclerosis, but recent data about Italian patients are missing. A multicenter observational and cross-sectional study was performed by students of hospital pharmacy to update existing data on quality of life and to correlate it with the pharmacological and medical history of patients. Quality of life (QoL) was assessed using the MS-QoL54 questionnaire, and the pharmacist collected patients’ characteristics, medical and pharmacological history, and Expanded Disability Status Scale (EDSS). Three hundred and forty-nine patients with multiple sclerosis were recruited from 16 centers between May 2018 and June 2019 (median age = 44.1 years; 68.9% women). The composite indexes of physical and mental well-being showed direct correlation with each other (R = 0.826; p < 0.001), and EDSS disability was an independent negative predictor of both indexes (R2 = 35.08% p < 0.001 and R2 = 15.74% p < 0.001, respectively). A trend of association between Physical Health Composite Score and different classes of oral disease-modifying drugs (DMDs) was observed. Our study found a decrease in QoL correlated with teriflunomide, which deserves further investigation. This experience demonstrates that joint action between scientific society and students association can be successful in conducting a no-profit multicenter observational study in a real-world setting.

Acting centrally or peripherally: A renewed interest in the central nervous system penetration of disease-modifying drugs in multiple sclerosis

With the recent approval of cladribine tablets, siponimod and ozanimod, there has been a renewed interest into the extent to which these current generation disease-modifying therapies (DMTs) are able to cross into the central nervous system (CNS), and how this penetration of the blood-brain barrier (BBB) may influence their ability to treat multiple sclerosis (MS).The integrity of the CNS is maintained by the BBB, blood-cerebrospinal fluid barrier, and the arachnoid barrier, which all play an important role in preserving the immunological environment and homeostasis within the CNS. The integrity of the BBB decreases during the course of MS, with a putative temporal relationship to disease worsening. Furthermore, it is currently considered that progression of the disease is mediated mainly by resident cells of the CNS.The existing literature provides evidence to show that some of the current generation DMTs for MS are able to penetrate the CNS and potentially exert direct effects on CNS-resident cells, in particular the CNS-penetrating prodrugs cladribine and fingolimod, and other sphingosine-1 phosphate receptor modulators; siponimod and ozanimod. Other current generation DMTs appear to be restricted to the periphery due to their high molecular weight or physicochemical properties.As more effective brain penetrant therapies are developed for the treatment of MS, there is a need to understand whether the potential for direct effects within the CNS are of significance, and whether this brings additional benefits over and above treatment effects mediated in the periphery. In turn, this will require an improved understanding of the structure and function of the BBB, the role it plays in MS and subsequent treatments.This narrative review summarizes the data supporting the biological plausibility of a potential benefit from therapeutic molecules entering the CNS, and discusses the potential significance in the current and future treatment of MS.

FTY720 Exacerbates Blood-Brain Barrier Dysfunction Induced by IgG Derived from Patients with NMO and MOG Disease.

Neuromyelitis optica (NMO) and myelin oligodendrocyte glycoprotein (MOG) antibody-related disease (MOG disease) are inflammatory demyelinating diseases of the central nervous system (CNS). The disruption of the blood-brain barrier (BBB) is considered a key step in the pathogenesis of NMO and MOG disease. Although a previous report indicated that circulating immunoglobulin G (IgG) from NMO patients disrupts the BBB, the effect of IgG from patients with MOG disease has not been elucidated. In addition, it has been reported that some disease-modifying drugs for multiple sclerosis are harmful to NMO by an unknown mechanism. This study aimed to examine the effects of IgG from patients with NMO or MOG disease on BBB integrity. We also examined the effects of disease-modifying drugs (fingolimod [FTY720] and dimethyl fumarate [DMF]) on IgG-treated brain capillary endothelial cells. We used in vitro BBB models constructed with rat brain capillary endothelial cells (RBECs) to examine the effects on BBB function. The integrity of the RBECs was assessed by measuring transendothelial resistance (TEER) and cell viability. NMO or MOG-IgG treatment decreased TEER and cell viability in the endothelial monolayer model. Although FTY720 and DMF did not affect barrier function or cell viability under normal conditions, disease IgG-induced barrier dysfunctions were worsened by the presence of FTY720. These data indicate that circulating IgG in patients with NMO or MOG disease worsens BBB function. Furthermore, in patients with NMO or MOG disease treated with FTY720, changes in the integrity of the BBB were found to exacerbate the disease.

An Overview of the Efficacy and Safety of Ozanimod for the Treatment of Relapsing Multiple Sclerosis.

Multiple sclerosis (MS) is a complex disease of the central nervous system that can cause permanent disability in young adults. A large armamentarium is available for its management and is increasing over time. Ozanimod is an oral drug belonging to the sphingosine-1-phosphate receptor (S1PR) modulator family recently approved in different countries for MS with active disease. It selectively modulates S1PR1 and S1PR5 to prevent autoreactive lymphocytes from entering the central nervous system (CNS), where they can determine inflammation and neurodegeneration. Ozanimod was tested in one Phase II and two Phase III pivotal trials and was shown to be effective and well tolerated. Moreover, further investigations, including comparative trials with other S1P modulators and MS disease-modifying drugs, are needed to better define placement in MS treatment. Furthermore, ozanimod is currently under evaluation for inflammatory bowel diseases, such as ulcerative colitis and Crohn’s disease, in international phase III studies. This article retraces the itinerary leading to the approval of ozanimod for MS treatment and its peculiarities and potentiality inside the S1PR modulator family.

Patient decision aid based on multi-criteria decision analysis for disease-modifying drugs for multiple sclerosis: prototype development

BackgroundSince decision making about treatment with disease-modifying drugs (DMDs) for multiple sclerosis (MS) is preference sensitive, shared decision making between patient and healthcare professional should take place. Patient decision aids could support this shared decision making process by providing information about the disease and the treatment options, to elicit the patient’s preference and to support patients and healthcare professionals in discussing these preferences and matching them with a treatment. Therefore, a prototype of a patient decision aid for MS patients in the Netherlands—based on the principles of multi-criteria decision analysis (MCDA) —was developed, following the recommendations of the International Patient Decision Aid Standards. MCDA was chosen as it might reduce cognitive burden of considering treatment options and matching patient preferences with the treatment options.ResultsAfter determining the scope to include DMDs labelled for relapsing-remitting MS and clinically isolated syndrome, users’ informational needs were assessed using focus groups (N = 19 patients) and best-worst scaling surveys with patients (N = 185), neurologists and nurses (N = 60) to determine which information about DMDs should be included in the patient decision aid. Next, an online format and computer-based delivery of the patient decision aid was chosen to enable embedding of MCDA. A literature review was conducting to collect evidence on the effectiveness and burden of use of the DMDs. A prototype was developed next, and alpha testing to evaluate its comprehensibility and usability with in total thirteen patients and four healthcare professionals identified several issues regarding content and framing, methods for weighting importance of criteria in the MCDA structure, and the presentation of the conclusions of the patient decision aid ranking the treatment options according to the patient’s preferences. Adaptations were made accordingly, but verification of the rankings provided, validation of the patient decision aid, evaluation of the feasibility of implementation and assessing its value for supporting shared decision making should be addressed in further development of the patient decision aid.ConclusionThis paper aimed to provide more transparency regarding the developmental process of an MCDA-based patient decision aid for treatment decisions for MS and the challenges faced during this process. Issues identified in the prototype were resolved as much as possible, though some issues remain. Further development is needed to overcome these issues before beta pilot testing with patients and healthcare professionals at the point of clinical decision-making can take place to ultimately enable making conclusions about the value of the MCDA-based patient decision aid for MS patients, healthcare professionals and the quality of care.

Drug safety in multiple sclerosis: From reporting to signal detection and benefit-risk management

Pharmacovigilance (PV) rules emerged in the late 60s-early 70s. Since that time, the World Health Organization Center for International Drug Monitoring carries out the corresponding tasks. Multiple sclerosis (MS) is a chronic inflammatory demyelinating disease of the central nervous system that generally starts in young adults between 20 and 40 years of age. Over the last 25 years, MS patients have benefited from the development of a plethora of disease modifying drugs (DMD). These changes in the therapeutic armamentarium have been associated with some serious adverse reactions challenging health authorities and neurologists involved in treatment and care for MS patients. The present review aims to describe, for MS DMDs, how adverse drug reactions are reported during clinical trials and the post-marketing period and how important signal detection and benefit-risk management have been in this disease until now. Several examples are reported to illustrate the different steps of PV processes. Improvement of the PV system procedures has led to significant progress in the detection of signals, allowing better assessment of the benefit-risk balance and the implementation of risk management plans for MS treatments. The involvement of neurologists is essential to improve knowledge on the benefit-risk balance of these drugs. In addition, adverse drug reactions reporting by persons with MS should be encouraged.

Medication adherence in multiple sclerosis as a potential model for other chronic diseases: a population-based cohort study

ObjectiveTo determine whether better medication adherence in multiple sclerosis (MS) might be due to specialised disease-modifying drug (DMD) support programmes by: (1) establishing higher adherence in MS than in other...

Prevalence of adverse pregnancy outcomes after exposure to interferon beta prior to or during pregnancy in women with MS: Stratification by maternal and newborn characteristics in a register-based cohort study in Finland and Sweden

BackgroundPrevious studies reported no increase in the prevalence of adverse pregnancy outcomes after exposure to interferon-beta (IFN-beta). However, no study has investigated if the prevalence of these outcomes after IFN-beta exposure is modified by maternal and newborn characteristics. Our objective was to describe the stratified prevalence of adverse pregnancy outcomes among women with multiple sclerosis (MS) exposed only to IFN-beta or unexposed to any MS disease modifying drugs (MSDMDs). MethodsThis population-based cohort study using Finnish (1996-2014) and Swedish (2005-2014) register data included pregnancies of women with MS exposed only to IFN-beta 6 months before or during pregnancy (n=718) or unexposed to MSDMDs (n=1397). The outcome prevalences were described stratified by maternal and newborn characteristics, with 95% confidence intervals (CIs). Confounder-adjusted analyses were performed if the prevalence results indicated modified effect of IFN-beta in specific strata. ResultsThe stratified analysis indicated that the prevalence of serious (anomaly or stillbirth) and other adverse pregnancy outcomes was similar among the exposed and unexposed, with no statistically significant difference. Among women treated for MS >5 years, serious adverse pregnancy outcomes occurred in 4.3% (95%CI: 1.9-8.3%) of pregnancies exposed only to IFN-beta 6 months before or during pregnancy and in 2.7% (95%CI: 1.2-5.0%) of unexposed pregnancies. The confounder adjusted analyses did not support the hypothesis that MS treatment duration before pregnancy would modify the risk of adverse pregnancy outcomes after exposure to IFN-beta 6 months before or during pregnancy. ConclusionThe prevalence of adverse pregnancy outcomes was not increased after IFN-beta exposure, when pregnancies of women with MS were stratified by maternal and newborn characteristics. The stratified results were similar to the unstratified results in the same population.

Recommendations for switching patients with highly active multiple sclerosis from other disease modifying drugs for multiple sclerosis to cladribine tablets

The need for optimal treatment of the active forms of multiple sclerosis (MS), especially highly active MS (HAMS), poses a number of difficult problems for specialists, including not only the choice of a highly effective disease-modifying drug for MS (DMDMS), but also conditions for the timely and safe switching from other DMDMS. A group of expert neurologists from various clinics in Russia presents a consensus on the practical aspects of switching patients with HAMS from other DMDMS to cladribine tablets, which has been registered in Russia in March 2020. The paper discusses indications for changing therapy and gives indications, contraindications, and conditions for initiating cladribine therapy. It details the procedure and results of the expert consensus, on the basis of which the recommendations have been developed to switch to cladribine tablets from each of the DMDMS registered in Russia for the treatment of MS.

Disease-modifying drugs can reduce disability progression in relapsing multiple sclerosis.

An ever-expanding number of disease-modifying drugs for multiple sclerosis have become available in recent years, after demonstrating efficacy in clinical trials. In the real-world setting, however, disease-modifying drugs are prescribed in patient populations that differ from those included in pivotal studies, where extreme age patients are usually excluded or under-represented. In this multicentre, observational, retrospective Italian cohort study, we evaluated treatment exposure in three cohorts of patients with relapsing-remitting multiple sclerosis defined by age at onset: paediatric-onset (≤18 years), adult-onset (18-49 years) and late-onset multiple sclerosis (≥50 years). We included patients with a relapsing-remitting phenotype, ≥5 years follow-up, ≥3 Expanded Disability Status Scale (EDSS) evaluations and a first neurological evaluation within 3 years from the first demyelinating event. Multivariate Cox regression models (adjusted hazard ratio with 95% confidence intervals) were used to assess the risk of reaching a first 12-month confirmed disability worsening and the risk of reaching a sustained EDSS of 4.0. The effect of disease-modifying drugs was assessed as quartiles of time exposure. We found that disease-modifying drugs reduced the risk of 12-month confirmed disability worsening, with a progressive risk reduction in different quartiles of exposure in paediatric-onset and adult-onset patients [adjusted hazard ratios in non-exposed versus exposed >62% of the follow-up time: 8.0 (3.5-17.9) for paediatric-onset and 6.3 (4.9-8.0) for adult-onset, P < 0.0001] showing a trend in late-onset patients [adjusted hazard ratio = 1.9 (0.9-4.1), P = 0.07]. These results were confirmed for a sustained EDSS score of 4.0. We also found that relapses were a risk factor for 12-month confirmed disability worsening in all three cohorts, and female sex exerted a protective role in the late-onset cohort. This study provides evidence that sustained exposure to disease-modifying drugs decreases the risk of disability accumulation, seemingly in a dose-dependent manner. It confirms that the effectiveness of disease-modifying drugs is lower in late-onset patients, although still detectable.