Mortality of neuromyelitis optica spectrum disorder patients in an Argentinean population: A study from the RelevarEM registry.

We aimed to evaluate mortality and causes of death among Argentinean neuromyelitis optica spectrum disorder (NMOSD) patients and identify predictors of death. Retrospective study included 158 NMOSD patients and 11 (7%) patients died after 11 years of follow-up for a total exposure time of 53,345 days with an overall incidence density of 2.06 × 10.000 patients/day (95% CI 1.75-2.68). Extensive cervical myelitis with respiratory failure (45%) was the most frequent cause of death. Older age (HR = 2.05, p = 0.002) and higher disability score (HR = 2.30, p < 0.001) at disease onset were independent predictors of death. We found an 11-year mortality rate of 7% in Argentinean NMOSD patients.

Evaluation of the use of high-efficacy treatments (HETs) in patients with relapsing-remitting multiple sclerosis in Argentina.

BACKGROUND: Disease-modifying therapies (DMTs) in multiple sclerosis (MS) can be classified according to the efficacy in which they prevent inflammatory activity. To date, there are limited data regarding the use of high-efficacy treatments (HETs) in Latin America (LATAM). We aimed to analyze the use of HETs in Argentina, focusing on the clinical and sociodemographic characteristics of the patients who use these treatments and the changes in the trend of use over the years. METHODS: A retrospective cohort study was done using the Argentina MS patient registry, RelevarEM. Patients diagnosed with relapsing-remitting MS (RRMS) according to validated diagnostic criteria and under treatment with natalizumab, alemtuzumab, cladribine, rituximab or ocrelizumab were included. RESULTS: Out of 2450 RRMS patients under a DMT, 462 (19%) were on HETs. One third of those patients (35%) received HETs as the first treatment. The most frequent reason for switching to HETs was treatment failure to previous DMT (77%). The time from MS diagnosis to the first HET in treatment-naive patients was less than one year (IQR: 0-1 year) and in treatment-experienced patients it was 5 years (IQR: 3-9 years). Between 2015 and 2017 (P1), 729 patients included in RelevarEM started a new treatment, of which 85 (11.65%) were HETs. Between 2018 and 2020 (P2), 961 patients included in RelevarEM started a new treatment, of which 284 (29.55%) were HETs. When comparing P2 with P1, a significant increase in the use of HETs was observed (p < 0.01). The most frequently used HETs were alemtuzumab (50.59%) in P1, and cladribine (45.20%) in P2. CONCLUSION: The demographic and clinical characteristics of patients under HET in Argentina were identified. Based on a real-world setting, we found a significant trend towards and a rapid increase in the use of HETs in clinical practice in patients with RRMS.

Achieving no evidence of disease activity-3 in highly active multiple sclerosis patients treated with cladribine and monoclonal antibodies.

Background: We aimed to determine the proportion of highly active multiple sclerosis patients under high-efficacy therapies (HETs) achieve no evidence of disease activity-3 (NEDA-3) at 1 and 2 years, and to identify factors associated with failing to meet no evidence of disease activity 3 at 2 years. Methods: This retrospective cohort study based on Argentina Multiple Sclerosis patient registry (RelevarEM), includes highly active multiple sclerosis patients who received HETs. Results: In total, 254 (78.51%) achieved NEDA-3 at year 1 and 220 (68.12%) achieved NEDA-3 at year 2. Patients who achieved NEDA-3 at 2 years had a shorter duration of multiple sclerosis (p < 0.01) and a shorter time between first treatment and current treatment (p = 0.01). Early high-efficacy strategy patients reached NEDA-3 more frequently (p < 0.01). Being a naïve patient (odds ratio: 3.78, 95% confidence interval 1.50-9.86, p < 0.01) was an independent predictor to reach NEDA-3 at 2 years. No association was found between type of HETs and NEDA-3 at 2 years when adjusted for potential confounders (odds ratio: 1.73; 95% confidence interval 0.51-6.06, p 0.57). Conclusion: We found a high proportion of patients who achieved NEDA-3 at 1 and 2 years. Early high-efficacy strategy patients had a higher probability of achieving NEDA-3 at 2 years.

Disability outcomes in NMOSD and MOGAD patients: data from a nationwide registry in Argentina.

The objective was to evaluate time to reach an EDSS of 4, 6, and 7 in NMOSD and MOGAD patients included in the Argentinean MS and NMOSD registry (RelevarEM, NCT 03,375,177). METHODS: NMOSD patients diagnosed according to 2015 criteria and with MOGAD were identified. Patients with at least 3 years of follow-up and periodic clinical evaluations with EDSS outcomes were included. AQP4-antibody and MOG-antibody status was recorded, and patients were stratified as seropositive and seronegative for AQP4-antibody. EDSS of 4, 6, and 7 were defined as dependent variables. Log rank test was used to identify differences between groups. RESULTS: Registry data was provided for a total of 137 patients. Of these, seventy-five presented AQP4-ab-positive NMOSD, 45 AQP4-ab-negative NMOSD, and 11 MOGAD. AQP4-ab status was determined by cell-based assay (CBA) in 72% of NMOSD patients. MOG-ab status was tested by CBA in all cases. Mean time to EDSS of 4 was 53.6 ± 24.5 vs. 63.1 ± 32.2 vs. 44.7 ± 32 months in seropositive, seronegative NMOSD, and MOGAD, respectively (p = 0.76). Mean time to EDSS of 6 was 79.2 ± 44.3 vs. 75.7 ± 48.6 vs. 54.7 ± 50 months in seropositive, seronegative NMOSD, and MOGAD (p = 0.23), while mean time to EDSS of 7 was 86.8 ± 54 vs. 80.4 ± 51 vs. 58.5 ± 47 months in seropositive, seronegative NMOSD, and MOGAD (p = 0.39). CONCLUSION: No differences were observed between NMOSD (seropositive and seronegative) and MOGAD in survival curves.

Incidence of COVID-19 after vaccination in people with multiple sclerosis in Argentina: Data from the nationwide registry RelevarEM.

The objective of the study was to evaluate the incidence of COVID-19 after complete vaccination in people with multiple sclerosis (PwMS) included in the Argentinean MS and NMOSD registry (RelevarEM, NCT03375177). METHODS: cohort study conducted between May 2021 and December 2021. The primary outcome was the appearance of infection during the follow-up time (at least three months after complete vaccination (second dose)). Data was collected through the contact between the treating physician and the patient. Specific information was requested (date, symptoms, need for hospitalization, ventilatory assistance, treatment, and evolution). The contact was made every 30 days during the period of 3 months after the full dose vaccination. A positive COVID-19 case was defined according to the definition established by the Ministry of Health in Argentina. Cumulative incidence was reported by Kaplan Meier survival curves as well as incidence density. RESULTS: A total of 576 PwMS were included, mean age 45.2 ± 13 years, 432 (75%) RRMS, 403 (70%) were female. The mean and median time of follow-up after the second dose was 91 ± 17 and 94 ± 21 days respectively. Most frequent first and second dose received was Astra-Zeneca vaccine, followed by Sputnik V vaccine. During follow-up a total of twenty COVID-19 cases were observed for a total exposure time of 39,557 days. The overall cumulative incidence for the observed period was 3.4% (SE 0.4%) with an overall incidence density of 5 × 10.000 patients/day (95%CI 0.7-12). We observed more cases in woman than men with an incidence density of 6 × 10.000 patients/day (95%CI 0.9-9) vs. 3 × 10.000 patients/day (95%CI 0.2-6) respectively, but not significantly different (IRR 1.7 95% CI 0.56-7.37 p = 0.15). CONCLUSION: we found an incidence density of breakthrough COVID-19 infection of 5 × 10.000 patients/day (95%CI 0.7-12) after vaccination in Argentina.

Clinical and demographic characteristics of male MS patients included in the national registry-RelevarEM. Does sex or phenotype make the difference in the association with poor prognosis?

BACKGROUND: In multiple sclerosis demographics there is a well-known female prevalence and male patients have been less specifically evaluated in clinical studies, though some clinical differences have been reported between sexes. OBJECTIVE: The objective of this study was to assess clinical and demographic differences between male and female patients included in the national Argentine MS Registry-RelevarEM. MATERIAL AND METHODS: This study was observational, retrospective, and was based on the data of 3099 MS patients included as of 04 April 2021. The statistical analysis plan included bivariate analyses with the crude data and also after adjustment for the MS phenotype, further categorized as progressive-onset MS or relapsing-onset MS. In the adjusted analysis, the Mantel-Haenszel odds ratio was compared to the crude odds ratio, to account for the phenotype as a confounder. RESULTS: The data from 1,074 (34.7%) men and 2,025 (65.3%) women with MS diagnosis were analysed. Males presented primary progressive disease two times more often than women (11% and 5%, respectively). In the crude analyses by sex, the presence of exclusively infratentorial lesions in the magnetic resonance imaging studies was more frequent in males than in females, but after adjustment by MS onset phenotype, such difference was only present in males with relapsing-onset MS (p = 0.00006). Similarly, worse Expanded Disability Status Scale scores were confirmed only in men with relapsing-onset disease after phenotype adjustment (p = 0.02). CONCLUSION: We did not find any statistically significant clinical or demographic difference between sexes when the progressive MS phenotype was specifically considered. However, the differences we found between the clinical phenotypes are in line with the literature and highlight the importance of stratifying the analyses by sex and phenotype when designing MS studies.

Rebound activity after fingolimod cessation: A case - control study.

BACKGROUND: There has been an increase in the number of reports of multiple sclerosis (MS) rebound activity (RA), which is usually defined as a severe disease reactivation after natalizumab or fingolimod withdrawal that exceeds pre-treatment baseline inflammatory activity. The frequency and risk factors that could predict RA remain unknown. Fingolimod is currently the most frequently prescribed disease modifying therapy for MS in Argentina, so that there is a need to determine possible predictors of RA. OBJECTIVES: To identify risk factors for developing RA after fingolimod cessation; to describe RA characteristics, management and evolution. METHODS: The study was a multicenter, retrospective, case-control study of patients with MS who had discontinued fingolimod and were followed up to nine months after discontinuation. Demographic, clinical and paraclinical data was extracted, including age, gender, MS phenotype, reason for discontinuation, number of relapses during the year prior to suspension, time treated with fingolimod, EDSS before, during and after rebound, MRI findings. RESULTS: 26 cases of RA were matched 1:1 with patients without RA. The median time elapsed to RA was 50 days. 68% showed worsening of the EDSS in the evaluation at 3 months of RA. When compared with the control group, no difference was found in terms of age, gender, phenotype, EDSS at the moment of suspension, reason for discontinuation, number of relapses in the previous year, and time on therapy. CONCLUSION: In this case-controlled study, no risk factors could be identified to predict RA after fingolimod cessation. Further controlled, prospective, better powered studies are needed to confirm these findings.

Accumulative risk of clinical event in high-risk radiologically isolated syndrome in Argentina: data from the nationwide registry RelevarEM.

INTRODUCTION: We aimed to analyze the accumulative risk of MRI and OB factors for evolution from RIS to MS in subjects included in the Argentinean MS registry (NCT03375177). METHODS: RIS subjects were identified according to RIS diagnosis criteria. Subjects were longitudinally followed with clinical and MRI at intervals of 6 months. Time from RIS identification to the first clinical event was estimated using Kaplan-Meier. Multivariable Cox regression models were created to assess the independent predictive value of demographic characteristics, as well as clinical, OB and MRI data on time to the first clinical event. The single and increased risk factor of evolution of RIS was quantified. RESULTS: A total of 88 RIS subjects, mean follow-up time 42 ± 4 months were included. 39 (44.3%) and 23 (26.1%) had a new MRI lesion or a clinical event, respectively, during the follow-up. OB (HR 5.9, 95% CI 1.29-10.1, p = 0.004), infratentorial lesions (HR 3.7, 95% CI 1.09-7.5) and spinal cord lesions (HR 5.3, 95% CI 1.4-8.2, p = 0.01) at RIS identification were independent predictors associated with a subsequent clinical event. The accumulative risk showed that when two of the three factors (OB, infratentorial or spinal cord lesions) were present the HR was 10.4, 95% CI 4.4-22, p < 0.001, and when three factors were present, it was HR 15.6, 95% CI 5.7-28, p < 0.001 for a relapse. CONCLUSION: The presence of three factors significantly increased the risk of clinical event; high-risk subjects should probably be managed by a different approach than those used for individuals without high-risk factors.

Seasonal variation in attacks of neuromyelitis optica spectrum disorders and multiple sclerosis: Evaluation of 794 attacks from a nationwide registry in Argentina.

BACKGROUND: Identification of triggers that potentially instigate attacks in neuromyelitis optica spectrum disorders (NMOSD) and multiple sclerosis (MS) has remained challenging. We aimed to analyze the seasonality of NMOSD and MS attacks in an Argentinean cohort seeking differences between the two disorders. METHODS: A retrospective study was conducted in a cohort of NMOSD and MS patients followed in specialized centers from Argentina and enrolled in RelevarEM, a nationwide, longitudinal, observational, non-mandatory registry of MS/NMOSD patients. Patients with complete relapse data (date, month and year) at onset and during follow-up were included. Attack counts were analyzed by month using a Poisson regression model with the median monthly attack count used as reference. RESULTS: A total of 551 patients (431 MS and 120 NMOSD), experiencing 236 NMOSD-related attacks and 558 MS-related attacks were enrolled. The mean age at disease onset in NMOSD was 39.5 ± 5.8 vs. 31.2 ± 9.6 years in MS (p < 0.01). Mean follow-up time was 6.1 ± 3.0 vs. 7.4 ± 2.4 years (p < 0.01), respectively. Most of the included patients were female in both groups (79% vs. 60%, p < 0.01). We found a peak of number of attacks in June (NMOSD: 28 attacks (11.8%) vs MS: 33 attacks (5.9%), incidence rate ratio 1.82, 95%CI 1.15-2.12, p = 0.03), but no differences were found across the months in both disorders when evaluated separately. Strikingly, we observed a significant difference in the incidence rate ratio of attacks during the winter season when comparing NMOSD vs. MS (NMOSD: 75 attacks (31.7%) vs MS: 96 attacks (17.2%), incidence rate ratio 1.82, 95%CI 1.21-2.01, p = 0.02) after applying Poisson regression model. Similar results were observed when comparing the seropositive NMOSD (n = 75) subgroup vs. MS. CONCLUSIONS: Lack of seasonal variation in MS and NMOSD attacks was observed when evaluated separately. Future epidemiological studies about the effect of different environmental factors on MS and NMOSD attacks should be evaluated prospectively in Latin America population.

Prevalence of Multiple Sclerosis in Rosario, Argentina.

BACKGROUND: The prevalence and incidence of Multiple Sclerosis have been increasing worldwide over the last decades. Most of the publications during the last years outstand the prevalence in Europe, North America and Latin America. In Argentina, data published on this topic is scarce and most of the studies took place in Buenos Aires. In a recent publication, we reported an MS prevalence rate of 30.3/100,000 in the overall extension of Santa Fe, Argentina, and in that study, we noticed that MS seemed to be more frequent in the southern region of the province. OBJECTIVE: In this study we aimed to estimate the prevalence of MS in Rosario (the third most populated district of Argentina), placed in the southeastern part of Santa Fe province. METHODS: This is a population based, cross-sectional study. We studied the members of the Province´s medical Care Program, a health maintenance organization of the public-sector employees that offers medical and health services to 567,819 members in the province 163,513 of whom have permanent residence in Rosario department, being a large representative sample. The selected prevalence date was 30 June 2019. Cases of MS were detected with a thorough search in the electronic databases of affiliates, linking and aggregating datasets. RESULTS: Seventy-nine MS cases were detected. The mean age was 47.7 (SD 13.5); female to male ratio was 3 to 1; the most frequent phenotype was relapsing-remitting (82.3%) followed by secondary-progressive (15.2%) and primary-progressive (2.5%). The crude prevalence rate of MS in Rosario as on 30 June 2019 was 48.3/100,000 inhabitants (95% CI: 48.28 - 48.35), 63.7/100,000 for females and 28.3/100,000 for males. The age-standardised MS prevalence rate was 43.4/100,000 inhabitants (95% CI:43.37 - 43.43) while the sex-standardised prevalence was estimated at 46.7/100,000 inhabitants (95% CI: 46.68 - 46.74). Making a proportional and linear projection to the total number of inhabitants, we deemed a total of 578 MS cases in Rosario, according to the 2010 census, and projected 620 cases by July 2019. CONCLUSION: This is the first study that provides epidemiological data of MS prevalence for Rosario. It confirms that there are differences in the distribution of MS in Santa Fe that favour the aggregation of cases in the southern part of the province. It also supplies updated and relevant data on the distribution of MS in Argentina and Latin America.

Assessing attacks and treatment response rates among adult patients with NMOSD and MOGAD: Data from a nationwide registry in Argentina.

We aimed to examine treatment interventions implemented in patients experiencing neuromyelitis optica spectrum disorders (NMOSD) attacks (frequency, types, and response). METHODS: Retrospective study. Data on patient demographic, clinical and radiological findings, and administered treatments were collected. Remission status (complete [CR], partial [PR], no remission [NR]), based on changes in the EDSS score was evaluated before treatment, during attack, and at 6 months. CR was analyzed with a generalized estimating equations (GEEs) model. RESULTS: A total of 131 patients (120 NMOSD and 11 myelin oligodendrocyte glycoprotein-antibody-associated diseases [MOGAD]), experiencing 262 NMOSD-related attacks and receiving 270 treatments were included. High-dose steroids (81.4%) was the most frequent treatment followed by plasmapheresis (15.5%). CR from attacks was observed in 47% (105/223) of all treated patients. During the first attack, we observed CR:71.2%, PR:16.3% and NR:12.5% after the first course of treatment. For second, third, fourth, and fifth attacks, CR was observed in 31.1%, 10.7%, 27.3%, and 33.3%, respectively. Remission rates were higher for optic neuritis vs. myelitis (p < 0.001). Predictor of CR in multivariate GEE analysis was age in both NMOSD (OR = 2.27, p = 0.002) and MOGAD (OR = 1.53, p = 0.03). CONCLUSIONS: This study suggests individualization of treatment according to age and attack manifestation. The outcome of attacks was generally poor.

Oral administration of methylprednisolone powder for intravenous injection dissolved in water to treat MS and NMOSD relapses during COVID-19 pandemic in a real-world setting.

BACKGROUND: Upon the COVID-19 pandemic emergence, safety concerns and logistic drawbacks stimulated the search for alternatives to pulse therapy at infusion centres to treat multiple sclerosis relapses. OBJECTIVE: To describe our experience treating multiple sclerosis relapses with a dilute injectable methylprednisolone powder orally administered, in a safe home-based environment and with totally virtual assessment and follow up via telemedicine. METHODS: Descriptive observational, retrospective, single-centre, open label, study in the real-world setting. RESULTS: Between August 2020 and March 2021, ten multiple sclerosis patients and one neuromyelitis optica spectrum disease patient, regularly assisted at our multiple sclerosis centre in Argentina, experienced twelve disease relapses (nine moderate/severe relapses and three mild relapses) and were treated with the oral dilute of injectable methylprednisolone powder pulses with good efficacy as well as adequate tolerance and safety profile. CONCLUSIONS: The oral pulse therapy based on the methylprednisolone powder dilution we describe is simple and comfortable to administer and can be an option in countries like Argentina, where the oral methylprednisolone formulation is not marketed. In these pandemic times, a home based and virtually monitored pulse therapy could represent a safe and effective alternative to manage relapses while minimizing the patient's risk of exposure to SARS-CoV-2.

COVID-19 in Argentine teriflunomide-treated multiple sclerosis patients: First national case series.

We report COVID-19 presentation, course and outcomes in teriflunomide-treated MS patients in Argentina. METHODS: descriptive, retrospective, multicentre, study that included MS patients receiving teriflunomide who developed COVID-19, with clinical follow-up at reference MS centres, also listed in a nationwide registry. RESULTS: Eighteen MS patients on teriflunomide treatment, from eight MS centres developed COVID-19. The mean age was 41,2 years and 72% of them were female; 94% had diagnosis of relapsing-remitting MS and 6% presented a radiologically isolated syndrome. Median EDSS was 2 (range 0-5.5). The average time on teriflunomide therapy was 3 years. COVID-19 diagnosis was confirmed with nasal swab in 61%. None required hospitalization and they completely recovered from the acute-phase within 7-14 days. All the patients continued their teriflunomide therapy during COVID-19 course. No MS relapses occurred during or after COVID-19 course. CONCLUSION: Our report adds to the evidence that COVID-19 is mild in patients receiving teriflunomide therapy and that continuing with teriflunomide therapy during Sars-CoV-2 infection is safe and advisable for MS patients.

COVID-19 in multiple sclerosis and neuromyelitis optica spectrum disorder patients in Latin America: COVID-19 in MS and NMOSD patients in LATAM.

BACKGROUND: There is no data regarding COVID-19 in Multiple Sclerosis (MS) and neuromyelitis optica spectrum disorder (NMOSD) patients in Latin America. OBJECTIVE: The objective of this study was to describe the clinical characteristics and outcomes of patients included in RELACOEM, a LATAM registry of MS and NMOSD patients infected with COVID-19. METHODS: RELACOEM is a longitudinal, strictly observational registry of MS and NMOSD patients who suffer COVID-19 and Dengue in LATAM. Inclusion criteria to the registry were either: (1) a biologically confirmed COVID-19 diagnosis based on a positive result of a COVID-19 polymerase chain reaction (PCR) test on a nasopharyngeal swab; or (2) COVID-19-typical symptoms (triad of cough, fever, and asthenia) in an epidemic zone of COVID-19. Descriptive statistics were performed on demographic and clinical variables. The cohort was later stratified for MS and NMOSD and univariate and multivariate logistic regression analysis was performed to identify variables associated with hospitalizations/intensive critical units (ICU) admission. RESULTS: 145 patients were included in the registry from 15 countries and 51 treating physicians. A total of 129 (89%) were MS patients and 16 (11%) NMOSD. 81.4% patients had confirmed COVID-19 and 18.6% were suspected cases. 23 (15.8%) patients were hospitalized, 9 (6.2%) required ICU and 5 (3.4 %) died due to COVID-19. In MS patients, greater age (OR 1.17, 95% CI 1.05 - 1.25) and disease duration (OR 1.39, 95%CI 1.14-1.69) were associated with hospitalization/ICU. In NMOSD patients, a greater age (54.3 vs. 36 years, p=<0.001), increased EDSS (5.5 vs 2.9, p=0.0012) and disease duration (18.5 vs. 10.3 years, p=0.001) were significantly associated with hospitalization/ICU. CONCLUSION: we found that in MS patients, age and disease duration was associated with hospitalization and ICU admission requirement, while age, disease duration and EDSS was associated in NMOSD.

What percentage of AQP4-ab-negative NMOSD patients are MOG-ab positive? A study from the Argentinean multiple sclerosis registry (RelevarEM).

BACKGROUND: Myelin oligodendrocyte glycoprotein antibodies (MOG-ab) have been described in aquaporin-4-antibodies(AQP4-ab)-negative neuromyelitis optica spectrum disorder (NMOSD) patients. We aimed to evaluate the percentage of AQP4-ab-negative NMOSD patients who are positive for MOG-ab in a cohort of Argentinean patients included in RelevarEM (Clinical Trials registry number NCT03375177). METHODS: RelevarEM is a longitudinal, strictly observational multiple sclerosis (MS) and NMOSD registry in Argentina. Of 3031 consecutive patients (until March 2020), 165 patients with phenotype of suspected NMOSD, whose relevant data for the purpose of this study were available, were included. Data on demographic, clinical, paraclinical and treatment in AQP4-ab (positive, negative and unknown) and MOG-ab (positive and negative) patients were evaluated. RESULTS: A total of 165 patients (79 AQP4-Ab positive, 67 AQP4-Ab negative and 19 unknown) were included. Of these, 155 patients fulfilled the 2015 NMOSD diagnostic criteria. Of 67 AQP4-Ab-negative patients, 36 (53.7%) were tested for MOG-Ab and 10 of them (27.7%) tested positive. Serum AQP4-ab levels were tested by means of cell-based assay (CBA) in 48 (35.2%), based on tissue-based indirect immunofluorescence assays in 58 (42.6%) and enzyme-linked immunosorbent assay in 4 (2.9%). All MOG-ab were tested by CBA. Optic neuritis (90%) was the most frequent symptom at presentation and optic nerve lesions the most frequent finding (80%) in neuroimaging of MOG-ab-associated disease. Of these, six (60%) patients were under immunosuppressant treatments at latest follow-up. CONCLUSION: We observed that 27.7% (10/36) of the AQP4-ab-negative patients tested for MOG-ab were positive for this antibody, in line with results from other world regions.

High birth weight and risk of multiple sclerosis: A multicentre study in Argentina.

BACKGROUND: Multiple sclerosis (MS) is now recognized as a multifactorial disease in which genetic and environmental factors intervene. Considerable efforts have been made to identify external risk factors present in childhood, adolescence and youth, though only a few perinatal risk factors have been positively associated with MS. Previously, we found an association between high birth weight and MS in male patients in a small study in Argentina. The present research was designed to further assess the association between high birth weight and MS in a larger sample of patients, using an extensive and validated general population database as control. METHODS: We present an analytical observational, multicentre, population-based, and case-control study. A total of 637 patients (cases) with confirmed MS diagnosis attending five MS specialized centres in Argentina were included. Birth weight (BW) data was recalled by the patient's mother, which is a validated approach. A two-way comparison was performed. First, we used the standard categories of high, adequate and low BW in grams. Then, we applied the weight percentile distribution to provide reproducible results for further research. For a proper assessment and comparison of variables, we adopted the guidelines of the American Academy of Pediatrics for neonate classification according to gestational weeks and to BW in grams. The neonate's BW distribution of the general population was used as control. For the purposes of the study, we adapted Urquía's et al. curves, which are based on an extensive database of all the live births registered in the country from 2003 to 2007. To measure the magnitude of the proportional differences between low, adequate and high BW, the odds ratio (OR) and their 95% confidence interval (CI) were estimated. The mean BW and percentile values for each sex were compared using a z-Normal test. The respective MS patients and general population BW distribution curves by sex were compared between each other. RESULTS: Cases and controls were comparable in their demographic, geographic and environmental characteristics. Males showed higher BW than females both in the MS patients and the general population groups. When we applied the sex stratified analysis separately, we found that males in the MS group showed an almost seven times higher risk of high birth weight than males from the general population (OR 6.58 [95% CI 4.81-8.99]). Female patients showed an almost five times higher risk of high BW than their respective controls (OR 4.5 [95% CI 3.06-6.58]). The comparison based on the BW percentile distribution confirmed that MS patients showed higher BW than the general population. This result reached statistical significance from the 75th percentile onwards for both sexes. CONCLUSION: In summary, our findings suggested that high BW could be one of the earliest risk factors for MS in life. If this results were reproduced in other centres, high birth weight would emerge as a novel and very early risk factor, potentially modifiable in utero or immediately postpartum, representing a unique opportunity to prevent the disease in future generations.

Correction to: Clinical and demographic characteristics of primary progressive multiple sclerosis in Argentina: Argentinean registry cohort study (RelevarEM).

The above article was published online with incorrect figure 1.

Clinical and demographic characteristics of primary progressive multiple sclerosis in Argentina: Argentinean registry cohort study (RelevarEM).

BACKGROUND: Primary progressive multiple sclerosis (PPMS) is an infrequent clinical form of multiple sclerosis (MS). Scarce information is available about PPMS in Latin America. The aim of this work is to describe the clinical and demographic characteristics of PPMS patients in Argentina. MATERIAL AND METHODS: RelevarEM is a longitudinal, strictly observational registry in Argentina. Clinical and epidemiological data from PPMS patients were described. RESULTS: There were 144 cases of PPMS. They represented 7% of MS patients. The mean age was 44.1 years. The female:male ratio was 1.08. The mean Expanded Disability Status Scale (EDSS) score was 5.5 and the mean disease evolution time was 10.6 years. Oligoclonal bands were found in 72.9%. At the time of diagnosis, magnetic resonance imaging showed spinal cord lesions in 82.6% and contrast-enhancing brain lesions in 18.1% of patients. Almost one third of patients were treated with a disease-modifying drug, and ocrelizumab was the most frequently used (55.8%). CONCLUSIONS: PPMS is an infrequent subtype of MS and its recognition is of the highest importance as it has its own evolution, treatment, and prognosis. The importance of our research resides in providing local data and contributing to a better understanding of PPMS and its treatment in Latin America.