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Background: In the absence of evidence from randomised controlled trials, observational data can be used to emulate clinical trials and guide clinical decisions. Observational studies are, however, susceptible to confounding and bias. Among the used techniques to reduce indication bias are propensity score matching and marginal structural models., Objective: To use the comparative effectiveness of fingolimod vs natalizumab to compare the results obtained with propensity score matching and marginal structural models., Methods: Patients with clinically isolated syndrome or relapsing remitting MS who were treated with either fingolimod or natalizumab were identified in the MSBase registry. Patients were propensity score matched, and inverse probability of treatment weighted at six monthly intervals, using the following variables: age, sex, disability, MS duration, MS course, prior relapses, and prior therapies. Studied outcomes were cumulative hazard of relapse, disability accumulation, and disability improvement., Results: 4608 patients (1659 natalizumab, 2949 fingolimod) fulfilled inclusion criteria, and were propensity score matched or repeatedly reweighed with marginal structural models. Natalizumab treatment was associated with a lower probability of relapse (PS matching: HR 0.67 [95% CI 0.62-0.80]; marginal structural model: 0.71 [0.62-0.80]), and higher probability of disability improvement (PS matching: 1.21 [1.02 -1.43]; marginal structural model 1.43 1.19 -1.72]). There was no evidence of a difference in the magnitude of effect between the two methods., Conclusions: The relative effectiveness of two therapies can be efficiently compared by either marginal structural models or propensity score matching when applied in clearly defined clinical contexts and in sufficiently powered cohorts.

Background: The MSBase prediction model of treatment response leverages multiple demographic and clinical characteristics to estimate hazards of relapses, confirmed disability accumulation (CDA), and confirmed disability improvement (CDI). The model did not include Multiple Sclerosis Severity Score (MSSS), a disease duration-adjusted ranked score of disability., Objective: To incorporate MSSS into the MSBase prediction model and compare model accuracy with and without MSSS., Methods: The associations between MSSS and relapse, CDA, and CDI were evaluated with marginal proportional hazards models adjusted for three principal components representative of patients' demographic and clinical characteristics. The model fit with and without MSSS was assessed with penalized r2 and Harrell C., Results: A total of 5866 MS patients were started on disease-modifying therapy during prospective follow-up (age 38.4 ± 10.6 years; 72% female; disease duration 8.5 ± 7.7 years). Including MSSS into the model improved the accuracy of individual prediction of relapses by 31%, of CDA by 23%, and of CDI by 24% (Harrell C) and increased the amount of variance explained for relapses by 49%, for CDI by 11%, and for CDA by 10% as compared with the original model., Conclusion: Addition of a single, readily available metric, MSSS, to the comprehensive MSBase prediction model considerably improved the individual accuracy of prognostics in MS.

Background: A delayed onset of treatment effect, termed therapeutic lag, may influence the assessment of treatment response in some patient subgroups., Objectives: The objective of this study is to explore the associations of patient and disease characteristics with therapeutic lag on relapses and disability accumulation., Methods: Data from MSBase, a multinational multiple sclerosis (MS) registry, and OFSEP, the French MS registry, were used. Patients diagnosed with MS, minimum 1 year of exposure to MS treatment and 3 years of pre-treatment follow-up, were included in the analysis. Studied outcomes were incidence of relapses and disability accumulation. Therapeutic lag was calculated using an objective, validated method in subgroups stratified by patient and disease characteristics. Therapeutic lag under specific circumstances was then estimated in subgroups defined by combinations of clinical and demographic determinants., Results: High baseline disability scores, annualised relapse rate (ARR) ⩾ 1 and male sex were associated with longer therapeutic lag on disability progression in sufficiently populated groups: females with expanded disability status scale (EDSS) < 6 and ARR < 1 had mean lag of 26.6 weeks (95% CI = 18.2-34.9), males with EDSS < 6 and ARR < 1 31.0 weeks (95% CI = 25.3-36.8), females with EDSS < 6 and ARR ⩾ 1 44.8 weeks (95% CI = 24.5-65.1), and females with EDSS ⩾ 6 and ARR < 1 54.3 weeks (95% CI = 47.2-61.5)., Conclusions: Pre-treatment EDSS and ARR are the most important determinants of therapeutic lag.

Background: The magnetic resonance imaging in multiple sclerosis (MAGNIMS) score combines relapses and magnetic resonance imaging (MRI) lesions to predict disability outcomes in relapsing-remitting multiple sclerosis (RRMS) treated with interferon-β., Objective: To validate the MAGNIMS score and extend to other disease-modifying therapies (DMTs). To examine the prognostic value of gadolinium contrast-enhancing (Gd+) lesions., Methods: This RRMS MSBase cohort study ( n  = 2293) used a Cox model to examine the prognostic value of relapses, MRI activity and the MAGNIMS score for disability worsening during treatment with interferon-β and three other DMTs., Results: Three new T2 lesions (hazard ratio (HR) = 1.60, p  = 0.028) or two relapses (HR = 2.24, p  = 0.002) on interferon-β (for 12 months) were predictive of disability worsening over 4 years. MAGNIMS score = 2 (1 relapse and ⩾3 T2 lesions or ⩾2 relapses) was associated with a greater risk of disability worsening on interferon-β (HR = 2.0, p  = 0.001). In pooled cohort of four DMTs, similar associations were seen (MAGNIMS score = 2: HR = 1.72, p  = 0.001). Secondary analyses demonstrated that the addition of Gd+ to the MAGNIMS did not materially improve its prediction of disability worsening., Conclusion: We have validated the MAGNIMS score in RRMS and extended its application to three other DMTs: 1 relapse and ⩾3 T2 lesions or ⩾2 relapses predicted worsening of disability. Contrast-enhancing lesions did not substantially improve the prognostic score.

Background: The risk factors for conversion from relapsing-remitting to secondary progressive multiple sclerosis remain highly contested., Objective: The aim of this study was to determine the demographic, clinical and paraclinical features that influence the risk of conversion to secondary progressive multiple sclerosis., Methods: Patients with adult-onset relapsing-remitting multiple sclerosis and at least four recorded disability scores were selected from MSBase, a global observational cohort. The risk of conversion to objectively defined secondary progressive multiple sclerosis was evaluated at multiple time points per patient using multivariable marginal Cox regression models. Sensitivity analyses were performed., Results: A total of 15,717 patients were included in the primary analysis. Older age (hazard ratio (HR) = 1.02, p  < 0.001), longer disease duration (HR = 1.01, p  = 0.038), a higher Expanded Disability Status Scale score (HR = 1.30, p  < 0.001), more rapid disability trajectory (HR = 2.82, p  < 0.001) and greater number of relapses in the previous year (HR = 1.07, p  = 0.010) were independently associated with an increased risk of secondary progressive multiple sclerosis. Improving disability (HR = 0.62, p  = 0.039) and disease-modifying therapy exposure (HR = 0.71, p  = 0.007) were associated with a lower risk. Recent cerebral magnetic resonance imaging activity, evidence of spinal cord lesions and oligoclonal bands in the cerebrospinal fluid were not associated with the risk of conversion., Conclusion: Risk of secondary progressive multiple sclerosis increases with age, duration of illness and worsening disability and decreases with improving disability. Therapy may delay the onset of secondary progression.

Background: The current best practice suggests yearly magnetic resonance imaging (MRI) to monitor treatment response in multiple sclerosis (MS) patients., Objective: To evaluate the current practice of clinicians changing MS treatment based on subclinical new MRI lesions alone., Methods: Using MSBase, an international MS patient registry with MRI data, we analysed the probability of treatment change among patients with clinically silent new MRI lesions., Results: A total of 8311 MRI brain scans of 4232 patients were identified. Around 26.9% (336/1247) MRIs with one new T2 lesion were followed by disease-modifying therapy (DMT) change, increasing to 50.2% (129/257) with six new T2 lesions. DMT change was twice as likely with new T1 contrast enhancing compared to new T2 lesions odds ratio (OR): 2.43, 95% confidence interval (CI): 2.00-2.96 vs OR: 1.26 (95% CI: 1.22-1.29). DMT change with new MRI lesions occurred most frequently with 'injectable' DMTs. The probability of switching therapy was greater only after high-efficacy therapies became available in 2007 (after, OR: 1.43, 95% CI: 1.28-1.59 vs before, OR: 0.98, 95% CI: 0.520-1.88)., Conclusion: MS clinicians rely increasingly on MRI alone in their treatment decisions, utilizing low thresholds (1 new T2 lesion) for optimizing MS therapy. This signals a shift towards no evidence of disease activity (NEDA)-3 since high-efficacy therapies became available.

Objective: This propensity score-matched analysis from MSBase compared the effectiveness of cladribine with interferon β, fingolimod or natalizumab., Methods: We identified all patients with relapse-onset multiple sclerosis, exposure to the study therapies and ⩾1-year on-treatment follow-up from MSBase. Three pairwise propensity score-matched analyses compared treatment outcomes over 1 year. The outcomes were hazards of first relapse, disability accumulation and disability improvement events. Sensitivity analyses were completed., Results: The cohorts consisted of 37 (cladribine), 1940 (interferon), 1892 (fingolimod) and 1410 patients (natalizumab). The probability of experiencing a relapse on cladribine was lower than on interferon ( p = 0.05), similar to fingolimod ( p = 0.31) and higher than on natalizumab ( p = 0.042). The probability of disability accumulation on cladribine was similar to interferon ( p = 0.37) and fingolimod ( p = 0.089) but greater than natalizumab ( p = 0.021). The probability of disability improvement was higher on cladribine than interferon ( p = 0.00017), fingolimod ( p = 0.0025) or natalizumab ( p = 0.00099). Sensitivity analyses largely confirmed the above results., Conclusion: Cladribine is an effective therapy for relapse-onset multiple sclerosis. Its effect on relapses is comparable to fingolimod and its effect on disability accrual is comparable to interferon β and fingolimod. Cladribine may potentially associate with superior recovery from disability relative to interferon, fingolimod and natalizumab.

Background: Several natural history studies on primary progressive multiple sclerosis (PPMS) patients detected a consistent heterogeneity in the rate of disability accumulation., Objectives: To identify subgroups of PPMS patients with similar longitudinal trajectories of Expanded Disability Status Scale (EDSS) over time., Methods: All PPMS patients collected within the MSBase registry, who had their first EDSS assessment within 5 years from onset, were included in the analysis. Longitudinal EDSS scores were modeled by a latent class mixed model (LCMM), using a nonlinear function of time from onset. LCMM is an advanced statistical approach that models heterogeneity between patients by classifying them into unobserved groups showing similar characteristics., Results: A total of 853 PPMS (51.7% females) from 24 countries with a mean age at onset of 42.4 years (standard deviation (SD): 10.8 years), a median baseline EDSS of 4 (interquartile range (IQR): 2.5-5.5), and 2.4 years of disease duration (SD: 1.5 years) were included. LCMM detected three different subgroups of patients with a mild ( n = 143; 16.8%), moderate ( n = 378; 44.3%), or severe ( n = 332; 38.9%) disability trajectory. The probability of reaching EDSS 6 at 10 years was 0%, 46.4%, and 81.9% respectively., Conclusion: Applying an LCMM modeling approach to long-term EDSS data, it is possible to identify groups of PPMS patients with different prognosis.

Background: Characteristics at clinically isolated syndrome (CIS) examination assist in identification of patient at highest risk of early second attack and could benefit the most from early disease-modifying drugs (DMDs)., Objective: To examine determinants of second attack and validate a prognostic nomogram for individualised risk assessment of clinical conversion., Methods: Patients with CIS were prospectively followed up in the MSBase Incident Study. Predictors of clinical conversion were analysed using Cox proportional hazards regression. Prognostic nomograms were derived to calculate conversion probability and validated using concordance indices., Results: A total of 3296 patients from 50 clinics in 22 countries were followed up for a median (inter-quartile range (IQR)) of 1.92 years (0.90, 3.71). In all, 1953 (59.3%) patients recorded a second attack. Higher Expanded Disability Status Scale (EDSS) at baseline, first symptom location, oligoclonal bands and various brain and spinal magnetic resonance imaging (MRI) metrics were all predictors of conversion. Conversely, older age and DMD exposure post-CIS were associated with reduced rates. Prognostic nomograms demonstrated high concordance between estimated and observed conversion probabilities., Conclusion: This multinational study shows that age at CIS onset, DMD exposure, EDSS, multiple brain and spinal MRI criteria and oligoclonal bands are associated with shorter time to relapse. Nomogram assessment may be useful in clinical practice for estimating future clinical conversion.

Objective: This study evaluated the effect of relapse phenotype on disability accumulation in multiple sclerosis., Methods: Analysis of prospectively collected data was conducted in 19,504 patients with relapse-onset multiple sclerosis and minimum 1-year prospective follow-up from the MSBase cohort study. Multivariable linear regression models assessed associations between relapse incidence, phenotype and changes in disability (quantified with Expanded Disability Status Scale and its Functional System scores). Sensitivity analyses were conducted., Results: In 34,858 relapses recorded during 136,462 patient-years (median follow-up 5.9 years), higher relapse incidence was associated with greater disability accumulation (β = 0.16, p < 0.001). Relapses of all phenotypes promoted disability accumulation, with the most pronounced increase associated with pyramidal (β = 0.27 (0.25-0.29)), cerebellar (β = 0.35 (0.30-0.39)) and bowel/bladder (β = 0.42 (0.35-0.49)) phenotypes (mean (95% confidence interval)). Higher incidence of each relapse phenotype was associated with an increase in disability in the corresponding neurological domain, as well as anatomically related domains., Conclusion: Relapses are associated with accumulation of neurological disability. Relapses in pyramidal, cerebellar and bowel/bladder systems have the greatest association with disability change. Therefore, prevention of these relapses is an important objective of disease-modifying therapy. The differential impact of relapse phenotypes on disability outcomes could influence management of treatment failure in multiple sclerosis.

Background: The results of head-to-head comparisons of injectable immunomodulators (interferon β, glatiramer acetate) have been inconclusive and a comprehensive analysis of their effectiveness is needed., Objective: We aimed to compare, in a real-world setting, relapse and disability outcomes among patients with multiple sclerosis (MS) treated with injectable immunomodulators., Methods: Pairwise analysis of the international MSBase registry data was conducted using propensity-score matching. The four injectable immunomodulators were compared in six head-to-head analyses of relapse and disability outcomes using paired mixed models or frailty proportional hazards models adjusted for magnetic resonance imaging variables. Sensitivity and power analyses were conducted., Results: Of the 3326 included patients, 345-1199 patients per therapy were matched (median pairwise-censored follow-up was 3.7 years). Propensity matching eliminated >95% of the identified indication bias. Slightly lower relapse incidence was found among patients treated with glatiramer acetate or subcutaneous interferon β-1a relative to intramuscular interferon β-1a and interferon β-1b (p≤0.001). No differences in 12-month confirmed progression of disability were observed., Conclusion: Small but statistically significant differences in relapse outcomes exist among the injectable immunomodulators. MSBase is sufficiently powered to identify these differences and reflects practice in tertiary MS centres. While the present study controlled indication, selection and attrition bias, centre-dependent variance in data quality was likely., (© The Author(s), 2014.)

Three women aged 34-47 years old, on high dose interferon beta-1a for relapsing-remitting multiple sclerosis, were hospitalized between 2009-2012 for thrombotic thrombocytopenic purpura-hemolytic uremic syndrome. Patients sought medical attention for neurological symptoms including cephalalgia, blurred vision, confusion, focal deficits and seizures. All patients presented thrombocytopenia, hemolytic anemia and arterial hypertension. Despite plasma exchanges, corticosteroids and anti-CD20 treatments, all patients progressed towards severe renal insufficiency and one patient died of hemorrhagic shock. In this report we identify a rare but morbid complication of interferon beta-1a treatment associated with female gender, Caucasian background and low body mass index., (© The Author(s) 2014.)

Objectives: The aim was to analyse risk of relapse phenotype recurrence in multiple sclerosis and to characterise the effect of demographic and clinical features on this phenotype., Methods: Information about relapses was collected using MSBase, an international observational registry. Associations between relapse phenotypes and history of similar relapses or patient characteristics were tested with multivariable logistic regression models. Tendency of relapse phenotypes to recur sequentially was assessed with principal component analysis., Results: Among 14,969 eligible patients (89,949 patient-years), 49,279 phenotypically characterised relapses were recorded. Visual and brainstem relapses occurred more frequently in early disease and in younger patients. Sensory relapses were more frequent in early or non-progressive disease. Pyramidal, sphincter and cerebellar relapses were more common in older patients and in progressive disease. Women presented more often with sensory or visual symptoms. Men were more prone to pyramidal, brainstem and cerebellar relapses. Importantly, relapse phenotype was predicted by the phenotypes of previous relapses. (OR = 1.8-5, p = 10(-14)). Sensory, visual and brainstem relapses showed better recovery than other relapse phenotypes. Relapse severity increased and the ability to recover decreased with age or more advanced disease., Conclusion: Relapse phenotype was associated with demographic and clinical characteristics, with phenotypic recurrence significantly more common than expected by chance., (© The Author(s), 2014.)

Background: Several studies have shown that pregnancy reduces multiple sclerosis (MS) relapses, which increase in the early postpartum period. Postpartum relapse risk has been predicted by pre-pregnancy disease activity in some studies., Objective: To re-examine effect of pregnancy on relapses using the large international MSBase Registry, examining predictors of early postpartum relapse., Methods: An observational case-control study was performed including pregnancies post-MS onset. Annualised relapse rate (ARR) and median Expanded Disability Status Scale (EDSS) scores were compared for the 24 months pre-conception, pregnancy and 24 months postpartum periods. Clustered logistic regression was used to investigate predictors of early postpartum relapses., Results: The study included 893 pregnancies in 674 females with MS. ARR (standard error) pre-pregnancy was 0.32 (0.02), which fell to 0.13 (0.03) in the third trimester and rose to 0.61 (0.06) in the first three months postpartum. Median EDSS remained unchanged. Pre-conception ARR and disease-modifying treatment (DMT) predicted early postpartum relapse in a multivariable model., Conclusion: Results confirm a favourable effect on relapses as pregnancy proceeds, and an early postpartum peak. Pre-conception DMT exposure and low ARR were independently protective against postpartum relapse. This novel finding could provide clinicians with a strategy to minimise postpartum relapse risk in women with MS planning pregnancy.

Background: With the advent of MRI scanning, the value of lumbar puncture to assess oligoclonal band (OCB) status-for the diagnosis of multiple sclerosis (MS) is increasingly uncertain. One major issue is that the reported frequency of cerebrospinal fluid (CSF)-restricted oligoclonal banding for the diagnosis of MS varies considerably in different studies. In addition, the relationship between OCB positivity and disease outcome remains uncertain, as reported studies are generally too small to assess comparative disability outcomes with sufficient power., Methods: In order to further investigate variation of OCB positivity in patients with MS, we utilized MSBase, a longitudinal, Web-based collaborative MS outcomes registry following clinical cohorts in several continents and latitudes. We also assessed whether OCB positivity affects long-term disability outcome., Results: A total of 13,242 patient records were obtained from 37 MS specialist centres in 19 different countries. OCB status was documented in 4481 (34%) patients and 80% of these were OCB positive. The presence of OCB was associated with degree of latitude (p = 0.02). Furthermore, the outcome of patients negative for CSF-specific OCB was significantly better in comparison to the OCB positive patients, as assessed by Expanded Disability Status Scale change (p < 0.001)., Conclusions: The results of this study indicate that latitude could explain some of the inconsistencies in OCB status reported in different populations. The study confirms that OCB positivity in MS is associated with a worse long-term prognosis.

Observational cohort studies are a powerful tool to assess the long-term outcome in chronic diseases. This study design has been utilized in local and regional outcome studies in multiple sclerosis (MS) and has yielded invaluable epidemiological information. The World Wide Web now provides an excellent opportunity for an international, collaborative cohort study of MS outcomes. A web platform--MSBase--has been designed to collect prospective data on patients with MS. It is purely observational, enabling participating neurologists to contribute data on diagnosis, treatment and progress, to review anonymous aggregate data and to benchmark their patient population against other patient subsets or the entire dataset. MSBase facilitates collaborative research by allowing the online creation of investigator-initiated regional, national and international substudies. The registry aims to answer epidemiological questions that can only be addressed by prospective assessments of large patient cohorts. The registry is funded through the independent MSBase Foundation, and governed by an International Scientific Advisory Board. The MSBase Foundation commenced operations in July 2004 and since then, 22 neurologists from 11 countries have joined MSBase and are contributing 2400 patients to the total data pool.