Purpose of review: Multiple sclerosis is a chronic, predominantly immune-mediated disease of the central nervous system, and one of the most common causes of neurological disability in young adults globally. This review will discuss the epidemiology, diagnosis, disease course, and prognosis of multiple sclerosis and will focus on recent evidence and advances in these aspects of the disease. Recent findings: Multiple sclerosis is increasing in incidence and prevalence globally, even in traditionally low-prevalence regions of the world. Recent revisions have been proposed to the existing multiple sclerosis diagnostic criteria, which will facilitate earlier diagnosis and treatment in appropriate patients. Classifying multiple sclerosis into distinct disease phenotypes can be challenging, and recent refinements have been proposed to clarify existing definitions. The prognosis of multiple sclerosis varies substantially across individual patients, and a combination of clinical, imaging, and laboratory markers can be useful in predicting clinical course and optimizing treatment in individual patients. Summary: A number of recent advances have been made in the clinical diagnosis and prognostication of multiple sclerosis patients. Future research will enable the development of more accurate biomarkers of disease categorization and prognosis, which will enable timely personalized treatment in individual multiple sclerosis patients.

Natural history studies have identified factors that predict evolution to multiple sclerosis or risk of disability accumulation over time. Although these studies are based on large multicentre cohorts with long follow-ups, they have limitations such as lack of standardized protocols, a retrospective data collection or lack of a systematic magnetic resonance imaging acquisition and analysis protocol, often resulting in failure to take magnetic resonance and oligoclonal bands into account as joint covariates in the prediction models. To overcome some of these limitations, the aim of our study was to identify and stratify baseline demographic, clinical, radiological and biological characteristics that might predict multiple sclerosis development and disability accumulation using a multivariate approach based on a large prospective cohort of patients with clinically isolated syndromes. From 1995 to 2013, 1058 patients with clinically isolated syndromes were included. We evaluated the influence of baseline prognostic factors on the risk for developing clinically definite multiple sclerosis, McDonald multiple sclerosis, and disability accumulation (Expanded Disability Status Scale score of 3.0) based on univariate (hazard ratio with 95% confidence intervals) and multivariate (adjusted hazard ratio with 95% confidence intervals) Cox regression models. We ultimately included 1015 patients followed for a mean of 81 (standard deviation = 57) months. Female/male ratio was 2.1. Females exhibited a similar risk of conversion to multiple sclerosis and of disability accumulation compared to males. Each younger decade at onset was associated with a greater risk of conversion to multiple sclerosis and with a protective effect on disability. Patients with optic neuritis had a lower risk of clinically definite multiple sclerosis [hazard ratio 0.6 (0.5–0.8)] and disability progression [hazard ratio 0.5 (0.3–0.8)]; however, this protective effect remained marginal only for disability [adjusted hazard ratio 0.6 (0.4–1.0)] in adjusted models. The presence of oligoclonal bands increased the risk of clinically definite multiple sclerosis [adjusted hazard ratio 1.3 (1.0–1.8)] and of disability [adjusted hazard ratio 2.0 (1.2–3.6)] independently of other factors. The presence of 10 or more brain lesions on magnetic resonance increased the risk of clinically definite multiple sclerosis [adjusted hazard ratio 11.3 (6.7–19.3)] and disability [adjusted hazard ratio 2.9 (1.4–6.0)]. Disease-modifying treatment before the second attack reduced the risk of McDonald multiple sclerosis [adjusted hazard ratio 0.6 (0.4–0.9)] and disability accumulation [adjusted hazard ratio 0.5 (0.3–0.9)]. We conclude that the demographic and topographic characteristics are low-impact prognostic factors, the presence of oligoclonal bands is a medium-impact prognostic factor, and the number of lesions on brain magnetic resonance is a high-impact prognostic factor.

To report the 5-year risk and to identify risk factors for the development of a seminal acute or progressive clinical event in a multi-national cohort of asymptomatic subjects meeting 2009 RIS Criteria. Retrospectively identified RIS subjects from 22 databases within 5 countries were evaluated. Time to the first clinical event related to demyelination (acute or 12-month progression of neurological deficits) was compared across different groups by univariate and multivariate analyses utilizing a Cox regression model. Data were available in 451 RIS subjects (F: 354 (78.5%)). The mean age at from the time of the first brain MRI revealing anomalies suggestive of MS was 37.2 years (y) (median: 37.1 y, range: 11–74 y) with mean clinical follow-up time of 4.4 y (median: 2.8 y, range: 0.01–21.1 y). Clinical events were identified in 34% (standard error = 3%) of individuals within a 5-year period from the first brain MRI study. Of those who developed symptoms, 9.6% fulfilled criteria for primary progressive MS. In the multivariate model, age [hazard ratio (HR): 0.98 (95% CI: 0.96–0.99); p = 0.03], sex (male) [HR: 1.93 (1.24–2.99); p = 0.004], and lesions within the cervical or thoracic spinal cord [HR: 3.08 (2.06–4.62); p = <0.001] were identified as significant predictors for the development of a first clinical event. These data provide supportive evidence that a meaningful number of RIS subjects evolve to a first clinical symptom. An age <37 y, male sex, and spinal cord involvement appear to be the most important independent predictors of symptom onset.

The prognostic role of cerebrospinal fluid molecular biomarkers determined in early pathogenic stages of multiple sclerosis has yet to be defined. In the present study, we aimed to investigate the prognostic value of chitinase 3 like 1 (CHI3L1), neurofilament light chain, and oligoclonal bands for conversion to clinically isolated syndrome and to multiple sclerosis in 75 patients with radiologically isolated syndrome. Cerebrospinal fluid levels of CHI3L1 and neurofilament light chain were measured by enzyme-linked immunosorbent assay. Uni- and multivariable Cox regression models including as covariates age at diagnosis of radiologically isolated syndrome, number of brain lesions, sex and treatment were used to investigate associations between cerebrospinal fluid CHI3L1 and neurofilament light chain levels and time to conversion to clinically isolated syndrome and multiple sclerosis. Neurofilament light chain levels and oligoclonal bands were independent risk factors for the development of clinically isolated syndrome (hazard ratio = 1.02, P = 0.019, and hazard ratio = 14.7, P = 0.012, respectively) and multiple sclerosis (hazard ratio = 1.03, P = 0.003, and hazard ratio = 8.9, P = 0.046, respectively). The best cut-off to classify cerebrospinal fluid neurofilament light chain levels into high and low was 619 ng/l, and high neurofilament light chain levels were associated with a trend to shorter time to clinically isolated syndrome (P = 0.079) and significant shorter time to multiple sclerosis (P = 0.017). Similarly, patients with radiologically isolated syndrome presenting positive oligoclonal bands converted faster to clinically isolated syndrome and multiple sclerosis (P = 0.005 and P = 0.008, respectively). The effects of high neurofilament light chain levels shortening time to clinically isolated syndrome and multiple sclerosis were more pronounced in radiologically isolated syndrome patients with ≥37 years compared to younger patients. Cerebrospinal fluid CHI3L1 levels did not influence conversion to clinically isolated syndrome and multiple sclerosis in radiologically isolated syndrome patients. Overall, these findings suggest that cerebrospinal neurofilament light chain levels and oligoclonal bands are independent predictors of clinical conversion in patients with radiologically isolated syndrome. The association with a faster development of multiple sclerosis reinforces the importance of cerebrospinal fluid analysis in patients with radiologically isolated syndrome.

The presence of oligoclonal bands in clinically isolated syndromes is an independent risk factor for developing multiple sclerosis and has been largely excluded from the more recent multiple sclerosis diagnostic criteria. Therefore, our objective was to explore the value of oligoclonal bands in the context of the 2010 McDonald criteria, especially in patients fulfilling exclusively dissemination in space at baseline. For this purpose, we selected 566 patients from a clinically isolated syndrome inception cohort who had IgG oligoclonal bands determination and sufficient data on baseline brain MRI to assess dissemination in space and time. We excluded the cases already fulfilling both dissemination in space and time and divided the remaining 398 into 'no dissemination in space and time' (n = 218), 'dissemination in space' (n = 164) and 'dissemination in time' (n = 16). We assessed Cox proportional hazards regression models with 2010 McDonald as the outcome, using 'no dissemination in space and time' with 0 lesions and negative oligoclonal bands as the reference for different subgroups according to oligoclonal bands status (positive/negative). To assess the diagnostic properties, we selected cases with a follow-up ≥3 years or fulfilling 2010 McDonald within 3 years of the clinically isolated syndrome (n = 314), and compared the performance of all 'dissemination in space' cases (n = 137) versus patients with 'dissemination in space' and positive oligoclonal bands (n = 101). The remaining patients classified as fulfilling 'dissemination in time' or 'no dissemination in space and time' were taken into account to calculate the diagnostic properties. The respective adjusted hazard ratios (95% confidence interval) were 1.5 (0.4-5.7) for 'no dissemination in space and time' with 0 lesions and positive oligoclonal bands, 3.1 (1.4-7.2) for 'no dissemination in space and time' with ≥1 lesions and negative oligoclonal bands, 7.4 (3.5-15.7) for 'no dissemination in space and time' with ≥1 lesions and positive oligoclonal bands, 10.4 (4.8-22.6) for 'dissemination in space' with negative oligoclonal bands, 15.3 (7.5-31.3) for 'dissemination in space' with positive oligoclonal bands, and 9.1 (3.5-23.4) for 'dissemination in time' (not subdivided due to the sample size). The specificity for all cases with 'dissemination in space' was 80.6 and increased to 88.1 after selecting those with positive oligoclonal bands. According to these results, we propose radiological dissemination in space at any time plus positive oligoclonal bands as an additional criterion for diagnosing multiple sclerosis.