Latitudinal prevalence gradient of multiple sclerosis in Latin America

Prevalence and incidence of multiple sclerosis in Turkey: A nationwide epidemiologic study

BACKGROUND

Many studies on multiple sclerosis (MS) reveal different prevalence and epidemiologic results.

OBJECTIVES

In this study, we aimed to determine the epidemiologic profile of MS using official health records in Turkey.

METHODS

Patients diagnosed with MS from the official health data of the Ministry of Health, representing the entire population of Turkey, were included in the study. Prevalence and incidence calculations were performed using the data on gender, age, year of birth, city of residence, and year of diagnosis.

RESULTS

As a result of the study, the number of patients with the ICD code G35 was determined as 201,061 and the number of patients with this code entered at least three times was determined as 82,225. The prevalence of MS in Turkey was calculated as 96.4 per 100,000 and the female/male ratio as 2.1/1. The incidence of MS in 2022 was 6.2 per 100,000 and the mean patient age was 43.1 ± 13.3 years (female: 43.0 ± 13.1 vs male: 43.2 ± 13.7) while the mean age at first diagnosis was 34.0 ± 13.0 (female: 33.6 ± 12.6 vs male: 34.9 ± 13.7).

CONCLUSION

The research was conducted via Official Database of Turkey, which includes population of 85 million and provides valuable insights into the prevalence and incidence rates of this chronic disease.

Triggering multiple sclerosis at conception and early gestation: The variation in ultraviolet radiation is as important as its intensity

Background and objectives

Medical science needs to further elucidate the role of ultraviolet radiation (UVR), geographic latitude, and the role of vitamin D in the autoimmune disease multiple sclerosis (MS). We separated several papers into categories out of the thousands published and used their conclusions to explore the relationship between UVR and MS.

Relevance

MS is increasing in incidence, particularly in women where MS is two to three times that in men and particularly severe in African Americans.

Methods

We collected UVR data at our observatory in Central Maine and calculated the average coefficient of variation (CVUVR) for each month for 15 years (2007-2021, inclusive).

Results

The month of conception (MOC) is more important than the month of birth (MOB) in explaining how UVR triggers the variable genetic predisposition to MS. We hypothesize that the rapidly increasing CVUVR is important in preventing an increase in the activity of the vitamin D receptor (VDR) from August to December, which then requires a higher intensity of UVR later in life to suppress the immune system, therefore predisposing to more MS.

Limitations

One observatory at about 44° latitude.

Conclusions

While variation in UVR is important at the MOC if UVR exceeds a threshold (e.g., if the sunspot number equals or is greater than 90, usually at a solar cycle MAX, or at elevations above approximately 3,000 feet above sea level), the MS mitigating vitamin D-VDR mechanism is overwhelmed and the genotoxic effects of higher-intensity UVR promote MS in those with a genetic predisposition.

What is new in this research

This paper offers a new concept in MS research.

Melatonin and vitamin D, two sides of the same coin, better to land on its edge to improve multiple sclerosis

Previous studies revealed a latitudinal gradient of multiple sclerosis (MS) prevalence, increasing by moving from the equator to the poles. The duration and quality of an individual's exposure to sunlight vary with latitude. Skin exposure to sunlight activates vitamin D synthesis, while light absence, as perceived by the eyes, activates melatonin synthesis in the pineal gland. Vitamin D or melatonin deficiency/insufficiency or overdose can occur at any latitude due to specific lifestyles and diets. Moving away from the equator, especially beyond 37°, decreases vitamin D while raising melatonin. Furthermore, melatonin synthesis increases in cold habitats like northern countries. Since melatonin's beneficial role was shown in MS, it is expected that northern countries whose individuals have higher endogenous melatonin should show a lower MS prevalence; however, these are ranked with the highest scores. In addition, countries like the United States and Canada have uncontrolled over-the-counter usage. In high latitudes, vitamin D deficiency and a higher MS prevalence persist even though vitamin D is typically compensated for by supplementation and not sunlight. Recently, we found that prolonged darkness increased MS melatonin levels, mimicking the long-term increase in northern countries. This caused a reduction in cortisol and increased infiltration, inflammation, and demyelination, which were all rescued by constant light therapy. In this review, we explain melatonin and vitamin D's possible roles in MS prevalence. The possible causes in northern countries are then discussed. Finally, we suggest strategies to treat MS by manipulating vitamin D and melatonin, preferably with sunlight or darkness, not supplements.

Incidence and prevalence of multiple sclerosis in China and other Asian countries

The prevalence of multiple sclerosis (MS) in Asian countries is thought to be lower than in Western countries, with Asian populations presenting 80% less risk of MS than white populations. Incidence and prevalence rates in Asian countries are therefore not well defined and their association with rates in neighboring countries, as well as with ethnic, environmental, and socioeconomic factors, are not well understood. We performed a comprehensive literature review of epidemiological data from China and neighbouring countries to study the frequency of the disease, focusing on prevalence, and the progression over time and the influence of sex-related, environmental, dietary, and sociocultural factors. Prevalence rates in China range between 0.88 cases/100,000 population in 1986 and 5.2 cases/100,000 population in 2013, with a non-significant upwards trend (p = .08). The increase observed in Japan, where figures ranged between 8.1 and 18.6 cases/100,000 population was highly significant (p < .001). Prevalence rates in countries with predominantly white populations are considerably higher and have increased over time, reaching 115 cases/100,000 population in 2015 (r² = 0.79, p < .0001). In conclusion, the prevalence of MS in China appears to have risen in recent years, although Asian populations (including Chinese and Japanese populations, among others) appear to present less risk than other populations. Within Asia, geographical latitude appears not to be a determining factor for developing MS.

The Economic and societal burden of multiple sclerosis on lebanese society: a cost-of-illness and quality of life study protocol

This protocol describes the estimation of the societal costs and quality-of-life (QOL) burden of multiple sclerosis (MS) in Lebanon. This cross-sectional, prevalence-based burden-of-illness study was carried out in a premier MS center in Lebanon. We enrolled Lebanese patients aged 18 years and older who had been diagnosed with MS more than 6 months. The study uses a bottom-up approach to estimate the cost-of-illness (COI) and QOL using a retrospective face-to-face interview questionnaire. This resource utilization questionnaire was adapted to the Lebanese context by clinical and health economics experts. The methodologies used to estimate the consumption of healthcare resources, informal care, and productivity losses are well-defined and aligned with the Lebanese healthcare system. Costs are presented overall and by MS severity levels. QOL is measured using the EuroQOL (EQ-5D-5 L) and Multiple Sclerosis International Quality of Life (MusiQoL) instrument. This protocol pioneers in informing the design of future COI and QOL studies in low - and middle-income countries (LMICs), as the methods used could be applied in similar LMICs. Furthermore, we provide recommendations and discuss the challenges of conducting a high-quality burden-of-illness study in LMICs and the steps taken to meet them, using the case of Lebanon.

Brainstem syndrome at onset is related to an early MS diagnosis in Peru: A national referral center cohort

Background

MS is unpredictable regarding clinical symptoms; however, certain symptoms represent the preferred localization of white matter lesions such as brainstem, spinal cord; or optic nerve.

Objectives

To investigate the epidemiological, clinical, and imaging characteristics of MS patients in a national referral center in Peru, and to evaluate whether the type of symptom at onset relates with the time to making an MS diagnosis.

Methods

Retrospective study of MS patients at the Instituto Nacional de Ciencias Neurológicas between January 2010 and December 2018. Four different syndromes were selected for analysis as symptom onset (optic neuritis, brainstem syndrome, myelitis, and others).

Results

we identified 268 patients for whom a diagnosis of MS had been given; after excluding misdiagnosed patients (33 Neuromyelitis optica), lost or incomplete records, 121 patients were included. The majority of patients (46.6%) were born in Lima. Female to male ratio was 1.37 to 1, mean age at diagnosis was 31 years. At onset, myelitis was present in 35% of RRMS patients, followed by brainstem syndrome (25%) and optic neuritis (18%). Brainstem syndrome was statistically significant predictor for earlier diagnosis (adjusted HR: 2.09; p = 0.015).

Conclusion

Brainstem syndrome as an initial presentation of MS in Peru is related to an earlier diagnosis.

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In Peru, the epidemiology of MS is still a major neglected topic.

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Brainstem syndrome as an initial presentation of MS in Peru is related to an early diagnosis.

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Our population represents different regions of our country.

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Similar clinical, epidemiological and imaging characteristic to other Latin American countries were found.

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We found a misdiagnosis rate of 36.2%, which remains a contemporary problem in MS diagnosis.

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.

Multiple sclerosis in Peru: National prevalence study using capture-recapture analysis

BACKGROUND

There is scarce epidemiological data on Multiple Sclerosis (MS) in Latin America. National epidemiological studies are needed to guide the health policy related to MS.

OBJECTIVE

To determine MS national prevalence in Peru and describe clinical and epidemiological characteristics of the disease.

METHODS

We conducted a cross-sectional prevalence study in Peru's four largest regions using two sources. We included adult patients diagnosed with MS by a neurologist using the McDonald criteria. We performed a capture-recapture analysis using the nearly unbiased estimator model, and calculated prevalence as the proportion of the adult Peruvian population in 2016. Additionally, we summarized patients epidemiological and clinical characteristics.

RESULTS

We identified 417 cases: 135 from the first source and 282 from the one. We found a point prevalence of 9.12 cases per 100 000 inhabitants (95% CI: 5.6 - 12.6). The age range was 35 to 45 years-old, and 51.9% were female. The most common type of MS was relapsing-remitting (79.3%) and the most frequent treatment was subcutaneous IFN-1b (40.7%).

CONCLUSION

Peru has a medium MS prevalence compared to other Latin American countries. Lima is the region with the highest number of cases, with similar clinical characteristics to other countries in the region.

Economic Burden of Multiple Sclerosis in Low- and Middle-Income Countries: A Systematic Review

BACKGROUND

Although the economic burden of multiple sclerosis (MS) in high-income countries (HICs) has been extensively studied, information on the costs of MS in low- and middle-income countries (LMICs) remains scarce. Moreover, no review synthesizing and assessing the costs of MS in LMICs has yet been undertaken.

OBJECTIVE

Our objective was to systematically identify and review the cost of illness (COI) of MS in LMICs to critically appraise the methodologies used, compare cost estimates across countries and by level of disease severity, and examine cost drivers.

METHODS

We conducted a systematic literature search for original studies in English, French, and Dutch containing prevalence or incidence-based cost data of MS in LMICs. The search was conducted in MEDLINE (Ovid), PubMed, Embase (Ovid), Cochrane Library, National Health Service Economic Evaluation Database (NHS EED), Econlit, and CINAHL (EBSCO) on July 2020 without restrictions on publication date. Recommended and validated methods were used for data extraction and analysis to make the results of the COI studies comparable. Costs were adjusted to $US, year 2019 values, using the World Bank purchasing power parity and inflated using the consumer price index.

RESULTS

A total of 14 studies were identified, all of which were conducted in upper-middle-income economies. Eight studies used a bottom-up approach for costing, and six used a top-down approach. Four studies used a societal perspective. The total annual cost per patient ranged between $US463 and 58,616. Costs varied across studies and countries, mainly because of differences regarding the inclusion of costs of disease-modifying therapies (DMTs), the range of cost items included, the methodological choices such as approaches used to estimate healthcare resource consumption, and the inclusion of informal care and productivity losses. Characteristics and methodologies of the included studies varied considerably, especially regarding the perspective adopted, cost data specification, and reporting of costs per severity levels. The total costs increased with greater disease severity. The cost ratios between different levels of MS severity within studies were relatively stable; costs were around 1-1.5 times higher for moderate versus mild MS and about two times higher for severe versus mild MS. MS drug costs were the main cost driver for less severe MS, whereas the proportion of direct non-medical costs and indirect costs increased with greater disease severity.

CONCLUSION

MS places a huge economic burden on healthcare systems and societies in LMICs. Methodological differences and substantial variations in terms of absolute costs were found between studies, which made comparison of studies challenging. However, the cost ratios across different levels of MS severity were similar, making comparisons between studies by disease severity feasible. Cost drivers were mainly DMTs and relapse treatments, and this was consistent across studies. Yet, the distribution of cost components varied with disease severity.

The latitude gradient for multiple sclerosis prevalence is established in the early lifecourse

The strongest epidemiological clue that the environment at the population level has a significant impact on the risk of developing multiple sclerosis (MS) is the well-established, and in many instances, increasing latitudinal gradient of prevalence, incidence and mortality globally, with prevalence increasing by up to 10-fold between the equator and 60 degrees North and South. The drivers of this gradient are thought to be environmental with latitude seen as a proxy for ultraviolet radiation and thus vitamin D production, however other factors may also play a role. However several important questions remain unanswered, particularly when in the life course is the gradient established, does lifetime migration mitigate or exacerbate previously reported latitude gradients at location of diagnosis, and do factors such as sex or MS disease phenotype influence the timing or significance of the gradient? Utilising life time residence calendars collected as part of the New Zealand national MS prevalence study, we constructed lifetime latitudinal gradients for MS from birth to prevalence day 2006 taking into account migration internally and externally and then analysed by sex and MS clinical course phenotype. 2127 of 2917 people living in NZ on prevalence day 7 March 2006 with MS completed the life course questionnaire and of these 1587 were born in NZ. All cohorts and sub cohorts were representative of the overall MS population in NZ on prevalence day. We found that the prevalence gradient was present at birth and was in fact stronger than at census day, and the slope of the gradient persisted until the age of 12 before gradually declining. We found that internal and external migration into NZ had little if any effect on the gradient except to decrease the significance of the gradient somewhat. Finally, we found as we had reported previously that the lifetime prevalence gradients were largely driven by females with relapse onset MS. These findings confirm for the first time the importance of early life environmental exposures in the risk of MS indicating strongly that exposures as early as in utero and at birth drive the latitudinal gradient. Consequently, prevention studies should be focussed on high risk individuals and populations from the earliest possible time points especially, when appropriate, on females.

Incidence and prevalence of multiple sclerosis in China and other Asian countries

The prevalence of multiple sclerosis (MS) in Asian countries is thought to be lower than in Western countries, with Asian populations presenting 80% less risk of MS than white populations. Incidence and prevalence rates in Asian countries are therefore not well defined and their association with rates in neighboring countries, as well as with ethnic, environmental, and socioeconomic factors, are not well understood. We performed a comprehensive literature review of epidemiological data from China and neighbouring countries to study the frequency of the disease, focusing on prevalence, and the progression over time and the influence of sex-related, environmental, dietary, and sociocultural factors. Prevalence rates in China range between 0.88 cases/100,000 population in 1986 and 5.2 cases/100,000 population in 2013, with a non-significant upwards trend (p = .08). The increase observed in Japan, where figures ranged between 8.1 and 18.6 cases/100,000 population was highly significant (p < .001). Prevalence rates in countries with predominantly white populations are considerably higher and have increased over time, reaching 115 cases/100,000 population in 2015 (r2 = 0.79, p < .0001). In conclusion, the prevalence of MS in China appears to have risen in recent years, although Asian populations (including Chinese and Japanese populations, among others) appear to present less risk than other populations. Within Asia, geographical latitude appears not to be a determining factor for developing MS.

Multiple sclerosis among first- and second-generation immigrant groups in Sweden

OBJECTIVES

Risk of multiple sclerosis (MS) is low among first-generation immigrants in Sweden. We aimed to study incident MS in first- and second-generation immigrant groups.

MATERIALS & METHODS

We included adults aged 18 years and older in Sweden in first-generation (n = 6 042 891) and second-generation (n = 4 860 469) sub-studies. MS was defined via two diagnoses in the Swedish National Patient Register. MS risk was estimated by Cox regression, with hazard ratios (HRs) and 95% confidence intervals (CI), in different immigrant groups, using Swedish-born as referents in first-generation sub-study, and individuals with Swedish-born parents in the second-generation. Full models were adjusted for age, geographic residence in Sweden, educational level, marital status, neighborhood socioeconomic status, and co-morbidity.

RESULTS

MS was diagnosed among 10 746 individuals in the first-generation sub-study, (men 3055 and women 7691), and 11 737 in the second-generation sub-study (men 3549 and women 8188) in the period 1998-2015. The annual incidence rate was higher in Swedish-born compared to foreign-born, 11.5 vs 6.3 per 100 000 person-years (age-standardized to the European standard population). Fully adjusted HRs were lower in first-generation immigrant men (HR 0.72, 0.64-0.82) and women (HR 0.67, 0.62-0.73), and in second-generation immigrant men (HR 0.88, 0.79-0.97) and women (HR 0.79; 0.73-0.84). Among first-generation immigrants, lower HRs were found in most groups.

SIGNIFICANCE

The MS risk was lower in first- and second-generation immigrants compared to Swedish-born or individuals with Swedish-born parents.

Latitude continues to be significantly associated with the prevalence of multiple sclerosis: an updated meta-analysis

OBJECTIVES

Previous studies have demonstrated a strong latitudinal gradient in multiple sclerosis (MS) prevalence. Herein, we present a meta-analysis of the latitudinal gradient of MS prevalence including studies published since our 2011 review, seeking to assess the latitudinal gradient and whether it has changed since our previous analysis.

METHODS

Studies published up to December 2018 were located via Embase, Web of Knowledge and PubMed, using standardised search terms; data were extracted from peer-reviewed studies and these studies added to those from our previous analysis. Where age-specific data were available, prevalence estimates were age-/sex-standardised to the 2009 European population. Prevalence estimates were adjusted for study prevalence year and ascertainment methods. The latitudinal association with MS prevalence was assessed by meta-regression.

RESULTS

A total of 94 studies met inclusion criteria, yielding 230 new prevalence points and 880 altogether with those from the prior study. There was a significant positive gradient in time-corrected MS prevalence with increasing latitude (5.27/100 000 per degree latitude), attenuating slightly to 4.34/100 000 on age-standardisation, these associations persisting on adjustment for ascertainment method. Of note, the age-standardised gradient was consistently significantly enhanced from our previous study, regardless of whether it was as-measured, time-corrected or adjusted for ascertainment methods. Certain areas, such as the Scandinavian and Atlantic Coast/Central Europe regions, showed changes in MS prevalence gradient over time, but other regional gradients were similar.

CONCLUSIONS

This new meta-analysis confirms that MS prevalence is still strongly positively associated with increasing latitude and that the gradient is increasing, suggesting that potentially modifiable environmental factors, such as sun exposure, are still strongly associated with MS risk.

Seasonal variations of 25-OH vitamin D serum levels in Multiple Sclerosis patients with relapse using MRI

An increasing body of evidence suggests that low vitamin D (25-[OH]-D) concentrations is linked to increased activity in multiple sclerosis (MS) patients and MS relapse. Therefore, the current study was aimed to evaluate vitamin D serum concentrations and its possible seasonal variations among MS patients with relapse. This prospective, descriptive study was conducted on patients with MS relapse who referred to the neurology center of Ali ibn Abi Talib Hospital in Zahedan during one year. Magnetic Resonance Imaging (MRI)-Spine was performed for 90 patients and serum samples were collected from patient to measure serum vitamin D levels using RIA KIT. Furthermore, the plaques in each patient's MRI were counted and then recorded. Descriptive and inductive statistics were conducted using statistical software. Our findings indicated a significant correlation between serum vitamin D level and cervical spinal cord plaques (p = 0.007, r = 0.28), while no association was revealed between serum vitamin D level and number of brain plaque. Furthermore, a significant association was also observed between number of cervical spinal cord plaques and serum vitamin D levels. In addition, a reverse correlation was observed between number of cervical spinal cord plaques and serum vitamin D levels in spring. In autumn, there was a statistically significant relationship between number of brain plaque and serum vitamin D level. Additionally, a statistically significant relationship was found between serum vitamin D levels and number of plaques in winter. Our findings are in agreement with some previous studies that reported conflicting result, where the association of season with the prevalence of relapse cases cannot be verified. Although the mean serum levels of vitamin D are inversely correlated with the incidence of relapses in winter. However, the values obtained in the spring do not confirm such an inverse relationship.

The Interaction between Viral and Environmental Risk Factors in the Pathogenesis of Multiple Sclerosis

Multiple sclerosis (MS) is a chronic debilitating inflammatory disease of unknown ethology targeting the central nervous system (CNS). MS has a polysymptomatic onset and is usually first diagnosed between the ages of 20–40 years. The pathology of the disease is characterized by immune mediated demyelination in the CNS. Although there is no clinical finding unique to MS, characteristic symptoms include sensory symptoms visual and motor impairment. No definitive trigger for the development of MS has been identified but large-scale population studies have described several epidemiological risk factors for the disease. This list is a confusing one including latitude, vitamin D (vitD) levels, genetics, infection with Epstein Barr Virus (EBV) and endogenous retrovirus (ERV) reactivation. This review will look at the evidence for each of these and the potential links between these disparate risk factors and the known molecular disease pathogenesis to describe potential hypotheses for the triggering of MS pathology.

Does the environment influence multiple sclerosis pathogenesis via UVB light and/or induction of vitamin D?

Multiple sclerosis (MS) is a disease of presumed auto-immune origin. Long-standing observations such as the correlation between MS incidence and geographical latitude or the levels of Vitamin D (Vit D) in the serum have implicated the environmental factors UVB radiation and diet in the etiology of the disease. Clinical trials have been conducted and are currently underway to elucidate whether a Vit D enriched diet or treatment with UVB can influence MS incidence, -severity, and -progression, as well as the ideal time point for treatment. This review summarizes the current scientific knowledge to the environmental factors UVB-light and Vit D concerning the clinical aspects of MS in epidemiological studies and clinical trials.

Structure-based selection of human metabolite binding P4 pocket of DRB1*15:01 and DRB1*15:03, with implications for multiple sclerosis

Binding of small molecules in the human leukocyte antigen (HLA) peptide-binding groove may result in conformational changes of bound peptide and an altered immune response, but previous studies have not considered a potential role for endogenous metabolites. We performed virtual screening of the complete Human Metabolite Database (HMDB) for docking to the multiple sclerosis (MS) susceptible DRB1*15:01 allele and compared the results to the closely related yet non-susceptible DRB1*15:03 allele; and assessed the potential impact on binding of human myelin basic peptide (MBP). We observed higher energy scores for metabolite binding to DRB1*15:01 than DRB1*15:03. Structural comparison of docked metabolites with DRB1*15:01 and DRB1*15:03 complexed with MBP revealed that Phenylalanine^MBP92 allows binding of metabolites in the P4 pocket of DRB1*15:01 but Valine^MBP89 abrogates metabolite binding in the P1 pocket. We observed differences in the energy scores for binding of metabolites in the P4 pockets of DRB1*15:01 vs. DRB1*15:03 suggesting stronger binding to DRB1*15:01. Our study confirmed that specific, disease-associated human metabolites bind effectively with the most polymorphic P4 pocket of DRB1*15:01, the primary MS susceptible allele in most populations. Our results suggest that endogenous human metabolites bound in specific pockets of HLA may be immunomodulatory and implicated in autoimmune disease.

Increasing Incidence and Prevalence of Multiple Sclerosis in Puerto Rico (2013-2016)

BACKGROUND

The incidence of multiple sclerosis (MS) has been increasing worldwide over the past decades. However, this upward trend has not been examined at the country level in Latin America and the Caribbean (LAC). The aims of this study are to examine trends of MS incidence over 4 years and to provide age- and gender-standardized incidence rate estimates for a Caribbean island.

METHODS

Data from the Puerto Rico (PR) MS Foundation's registry was used to identify all newly diagnosed MS cases between 2013 and 2016. MS patients were 18 years and older and met the 2010 revised McDonald criteria. Age- and gender-standardized incidence rates were estimated.

RESULTS

A total of 583 new MS cases were diagnosed in PR from 2013 to 2016. The age- and gender-standardized MS incidence rate for PR increased from 6.1/100,000 in 2013 to 6.7/100,000 in 2016. The annual age-standardized MS incidence rates for females rose from 8.4/100,000 in 2013 to 9.8/100,000 in 2016 and were higher than males, which remained around 3.7/100,000.

CONCLUSION

Incidence estimates for PR were higher than other LAC countries but consistent with MS increases in other world regions. Our findings tend to rule out several prior potential environmental explanations for high MS incidence rates.

A survey of the clinicopathological and molecular characteristics of patients with suspected Lynch syndrome in Latin America

BACKGROUND

Genetic counselling and testing for Lynch syndrome (LS) have recently been introduced in several Latin America countries. We aimed to characterize the clinical, molecular and mismatch repair (MMR) variants spectrum of patients with suspected LS in Latin America.

METHODS

Eleven LS hereditary cancer registries and 34 published LS databases were used to identify unrelated families that fulfilled the Amsterdam II (AMSII) criteria and/or the Bethesda guidelines or suggestive of a dominant colorectal (CRC) inheritance syndrome.

RESULTS

We performed a thorough investigation of 15 countries and identified 6 countries where germline genetic testing for LS is available and 3 countries where tumor testing is used in the LS diagnosis. The spectrum of pathogenic MMR variants included MLH1 up to 54%, MSH2 up to 43%, MSH6 up to 10%, PMS2 up to 3% and EPCAM up to 0.8%. The Latin America MMR spectrum is broad with a total of 220 different variants which 80% were private and 20% were recurrent. Frequent regions included exons 11 of MLH1 (15%), exon 3 and 7 of MSH2 (17 and 15%, respectively), exon 4 of MSH6 (65%), exons 11 and 13 of PMS2 (31% and 23%, respectively). Sixteen international founder variants in MLH1, MSH2 and MSH6 were identified and 41 (19%) variants have not previously been reported, thus representing novel genetic variants in the MMR genes. The AMSII criteria was the most used clinical criteria to identify pathogenic MMR carriers although microsatellite instability, immunohistochemistry and family history are still the primary methods in several countries where no genetic testing for LS is available yet.

CONCLUSION

The Latin America LS pathogenic MMR variants spectrum included new variants, frequently altered genetic regions and potential founder effects, emphasizing the relevance implementing Lynch syndrome genetic testing and counseling in all of Latin America countries.

Prevalence of multiple sclerosis in Latin America and its relationship with European migration

Multiple sclerosis (MS) is a chronic, degenerative autoimmune inflammatory disease of the central nervous system. The prevalence is different in every continent, changing according to geographical and environmental characteristics. The areas with the highest prevalence in the world are Europe and North America. In Latin America, the prevalence is higher in areas where there was greater European migration, as in the case of Argentina, Chile, Brazil, Uruguay and Mexico, and there have been no identified cases amongst native Indian populations. It should be considered that environmental factors may influence the prevalence of MS in Latin America, and it seems as if there are protective factors such as exposure to ultraviolet radiation and the presence of parasitosis.

Multiple sclerosis epidemiology in Latin America: An updated survey

Novel epidemiological data have appeared in recent years in Latin America (LATAM). The objective of this study was to perform an updated systematic review of the epidemiology of the disease reported in LATAM.

The Skin-Brain Connection Hypothesis, Bringing Together CCL27-Mediated T-Cell Activation in the Skin and Neural Cell Damage in the Adult Brain

Recent discovery of an association of low serum melatonin levels with relapse in multiple sclerosis (MS) opens a new horizon in understanding the pathogenesis of this disease. Skin is the main organ for sensing seasonal changes in duration of sunlight exposure. Level of melatonin production is dependent on light exposure. The molecular mechanisms connecting peripheral (skin) sensing of the light exposure and developing brain inflammation (MS) have not been investigated. We hypothesize that there is a connection between the reaction of skin to seasonal changes in sunlight exposure and the risk of MS and that seasonal changes in light exposure cause peripheral (skin) inflammation, the production of cytokines, and the subsequent inflammation of the brain. In skin of genetically predisposed individuals, cytokines attract memory cutaneous lymphocyte-associated antigen (CLA+) T lymphocytes, which then maintain local inflammation. Once inflammation is resolved, CLA+ lymphocytes return to the circulation, some of which eventually migrate to the brain. Once in the brain these lymphocytes may initiate an inflammatory response. Our observation of increased CC chemokine ligand 27 (CCL27) in MS sera supports the involvement of skin in the pathogenesis of MS. Further, the importance of our data is that CCL27 is a chemokine released by activated keratinocytes, which is upregulated in inflamed skin. We propose that high serum levels of CCL27 in MS are the result of skin inflammation due to exposure to seasonal changes in the sunlight. Future studies will determine whether CCL27 serum level correlates with seasonal changes in sunlight exposure, MS exacerbation, and skin inflammation.

Epidemiology of Multiple Sclerosis

The epidemiology of multiple sclerosis (MS) includes a consideration of genetic and environmental factors. Comparative studies of different populations have revealed prevalence and incidence rates that vary with geography and ethnicity. With a prevalence ranging from 2 per 100,000 in Japan to greater than 100 per 100,000 in Northern Europe and North America, the burden of MS is similarly unevenly influenced by longevity and comorbid disorders. Well-powered genome-wide association studies have investigated the genetic substrate of MS, providing insight into autoimmune mechanisms involved in the etiopathogenesis of MS and elucidating possible avenues of biological treatment.

A Method of Trigonometric Modelling of Seasonal Variation Demonstrated with Multiple Sclerosis Relapse Data

This report describes a novel Stata-based application of trigonometric regression modelling to 55 years of multiple sclerosis relapse data from 46 clinical centers across 20 countries located in both hemispheres. Central to the success of this method was the strategic use of plot analysis to guide and corroborate the statistical regression modelling. Initial plot analysis was necessary for establishing realistic hypotheses regarding the presence and structural form of seasonal and latitudinal influences on relapse probability and then testing the performance of the resultant models. Trigonometric regression was then necessary to quantify these relationships, adjust for important confounders and provide a measure of certainty as to how plausible these associations were. Synchronization of graphing techniques with regression modelling permitted a systematic refinement of models until best-fit convergence was achieved, enabling novel inferences to be made regarding the independent influence of both season and latitude in predicting relapse onset timing in MS. These methods have the potential for application across other complex disease and epidemiological phenomena suspected or known to vary systematically with season and/or geographic location.

Central Nervous System Idiopathic Inflammatory Demyelinating Disorders in South Americans: A Descriptive, Multicenter, Cross-Sectional Study

The idiopathic inflammatory demyelinating disease (IIDD) spectrum has been investigated among different populations, and the results have indicated a low relative frequency of neuromyelitis optica (NMO) among multiple sclerosis (MS) cases in whites (1.2%-1.5%), increasing in Mestizos (8%) and Africans (15.4%-27.5%) living in areas of low MS prevalence. South America (SA) was colonized by Europeans from the Iberian Peninsula, and their miscegenation with natives and Africans slaves resulted in significant racial mixing. The current study analyzed the IIDD spectrum in SA after accounting for the ethnic heterogeneity of its population. A cross-sectional multicenter study was performed. Only individuals followed in 2011 with a confirmed diagnosis of IIDD using new diagnostic criteria were considered eligible. Patients’ demographic, clinical and laboratory data were collected. In all, 1,917 individuals from 22 MS centers were included (73.7% female, 63.0% white, 28.0% African, 7.0% Mestizo, and 0.2% Asian). The main disease categories and their associated frequencies were MS (76.9%), NMO (11.8%), other NMO syndromes (6.5%), CIS (3.5%), ADEM (1.0%), and acute encephalopathy (0.4%). Females predominated in all main categories. The white ethnicity also predominated, except in NMO. Except in ADEM, the disease onset occurred between 20 and 39 years old, early onset in 8.2% of all cases, and late onset occurred in 8.9%. The long-term morbidity after a mean disease time of 9.28±7.7 years was characterized by mild disability in all categories except in NMO, which was scored as moderate. Disease time among those with MS was positively correlated with the expanded disability status scale (EDSS) score (r=0.374; p=<0.001). This correlation was not observed in people with NMO or those with other NMO spectrum disorders (NMOSDs). Among patients with NMO, 83.2% showed a relapsing-remitting course, and 16.8% showed a monophasic course. The NMO-IgG antibody tested using indirect immunofluorescence (IIF) with a composite substrate of mouse tissues in 200 NMOSD cases was positive in people with NMO (95/162; 58.6%), longitudinally extensive transverse myelitis (10/30; 33.3%) and bilateral or recurrent optic neuritis (8/8; 100%). No association of NMO-IgG antibody positivity was found with gender, age at onset, ethnicity, early or late onset forms, disease course, or long-term severe disability. The relative frequency of NMO among relapsing-remitting MS (RRMS) + NMO cases in SA was 14.0%. Despite the high degree of miscegenation found in SA, MS affects three quarters of all patients with IIDD, mainly white young women who share similar clinical characteristics to those in Western populations in the northern hemisphere, with the exception of ethnicity; approximately one-third of all cases occur among non-white individuals. At the last assessment, the majority of RRMS patients showed mild disability, and the risk for secondary progression was significantly superior among those of African ethnicity. NMO comprises 11.8% of all IIDD cases in SA, affecting mostly young African-Brazilian women, evolving with a recurrent course and causing moderate or severe disability in both ethnic groups. The South-North gradient with increasing NMO and non-white individuals from Argentina, Paraguay, Brazil and Venezuela confirmed previous studies showing a higher frequency of NMO among non-white populations.

Latitude has more significant impact on prevalence of multiple sclerosis than ultraviolet level or sunshine duration in Japanese population

Higher latitude is known to be associated with higher prevalence of multiple sclerosis (MS). We investigated the degree of impact of latitude, ultraviolet (UV) radiation, and sunshine on the prevalence of MS in Japan, which has 47 prefectures with a variety of climates. MS prevalence in each prefecture was collected from database of the Ministry of Health, Labour, and Welfare of Japan. Latitude of each prefecture was represented by that of the capital city. Data of UV radiation level and annual actual sunshine duration were obtained from databases of Japan Meteorological Agency. We performed linear correlation analyses of MS prevalence against latitude, UV radiation, and annual actual sunshine duration. MS prevalence significantly correlated to latitude (Pearson's correlation, r = 0.69, p < 0.001) and UV radiation level (r = -0.65, p < 0.001) but not to annual actual sunshine duration (r = -0.37, p = 0.011). Stepwise multiple linear regression analyses revealed significant correlation between MS prevalence and only latitude (p < 0.001). While our result shows that both latitude and the UV intensity have significant relationship to MS prevalence, the stronger relevance of the former suggests an existence of risk factors other than UV radiation.

Personalization of multiple sclerosis treatments: using the chelation therapy approach

Though Multiple Sclerosis (MS) sufferers are probably genetically predisposed, toxic metal poisoning (TMP) does seem an increasingly likely environmental trigger. The technique for measuring and clearing TMP was chelation therapy using ethylene-diamine-tetracetic acid (EDTA), which revealed aluminum accumulation in both cases. The first patient, initially benefiting from removing dental fillings that had leaked mercury, also showed gadolinium accumulation from scan contrast medium, and a genomic deficiency of glutathione transferase M1. Glutathione production was impaired and hence also liver detoxification functions. The personal protocol involved glutathione administration and deutrosulfazyme to enhance oxygenation and alleviate oxidative stress. As aluminum began to clear with EDTA infusion, the extracellular/intracellular water ratio was carefully monitored, and carbohydrates limited. In the second case, aluminum poisoning responded to EDTA chelation therapy with eicosapentaenoic acid (EPA)/docosahexaenoic acid (DHA), multivitamins, and glutathione administration, again followed by deutrosulfazyme, water ratio control, and dietary correction. The two personalized protocols presented here tend to confirm the hypothesis of TMP as an environmental or iatrogenic trigger for MS, especially when inadequate detoxification lies at the root. Cleansing by chelation therapy, properly understood, can be efficacious, especially bearing in mind the altered cellular water ratio.

Cost of care according to disease-modifying therapy in Mexicans with relapsing-remitting multiple sclerosis

Limited data exist on the costs of care of patients with multiple sclerosis (MS) in low- to middle-income nations. The purpose of this study was to describe the economic burden associated with care of Mexican patients with relapsing-remitting MS in a representative sample of the largest institution of the Mexican public healthcare system. We analysed individual data of 492 patients (67% women) with relapsing-remitting MS registered from January 2009 to February 2011 at the Mexican Social Security Institute. Direct costs were measured about the use of diagnostic tests, disease-modifying therapies (DMTs), symptoms control, medical consultations, relapses, intensive care and rehabilitation. Four groups were defined according to DMT alternatives: (1) interferon beta (IFNβ)-1a, 6 million units (MU); (2) IFNβ-1a, 12MU; (3) IFNβ-1b, 8MU; and (4) glatiramer acetate. All patients received DMTs for at least 1 year. The most frequently used DMT was glatiramer acetate (45.5%), followed by IFNβ-1a 12MU (22.6%), IFNβ-1b 8MU (20.7%), and IFNβ-1a 6MU (11.2%). The mean cost of a specialised medical consultation was €74.90 (US $107.00). A single relapse had a mean total cost of €2,505.97 (US $3,579.96). No differences were found in annualised relapse rates and costs of relapses according to DMT. However, a significant difference was observed in total annual costs according to treatment groups (glatiramer acetate being the most expensive), mainly due to differences in unitary costs of alternatives. From the public institutional perspective, when equipotent DMTs are used in patients with comparable characteristics, the costs of DMTs largely determine the total expenses associated with care of patients with relapsing-remitting MS in a middle-income country.

Incidence and prevalence of multiple sclerosis in the Americas: a systematic review

BACKGROUND

The incidence and prevalence of multiple sclerosis (MS) varies considerably around the world. No previous study has performed a comprehensive review examining the incidence and prevalence of MS across the Americas. The purpose of this study was to systematically review and assess the quality of studies estimating the incidence and/or prevalence of MS in North, Central and South American regions.

METHODS

A comprehensive literature search was performed using MEDLINE and EMBASE from January 1985 to January 2011. Search terms included 'multiple sclerosis', 'incidence', 'prevalence' and 'epidemiology'. Only full-text articles published in English or French were included. Study quality was assessed using an assessment tool based on recognized guidelines and designed specifically for this study.

RESULTS

A total of 3,925 studies were initially identified, with 31 meeting the inclusion criteria. The majority of studies examined North American regions (n = 25). Heterogeneity was high among all studies, even when stratified by country. Only half of the studies reported standardized rates, making comparisons difficult. Quality scores ranged from 3/8 to 8/8.

CONCLUSION

This review highlights the gaps that still exist in the epidemiological knowledge of MS in the Americas, and the inconsistencies in methodologies and quality among the published studies. There is a need for future studies of MS prevalence and incidence to include uniform case definitions, employ comparable methods of ascertainment, report standardized results, and be performed on a national level. Other factors such as sex distribution, ethnic make-up and population lifestyle habits should also be considered.

Burden of disease of multiple sclerosis in Korea

OBJECTIVES

Multiple sclerosis (MS) is an inflammatory demyelinating disease of the central nervous system. There are few reports on the burden of disease of MS, worldwide. The authors aim to estimate burden of disease and estimate the epidemiologic indexes of MS in Korea using available epidemiologic data.

METHODS

Epidemiologic indexes were computed using DISMOD II software based on prevalence from nationwide survey, incidence estimated from extrapolation, mortality from National Statistics Office, and duration of disease from literature as input indexes. We calculated disability-adjusted life year (DALY) as a measure of premature mortality and disability, equivalent to years of healthy life lost due to a given condition.

RESULTS

The incidence of MS in Korea was 0.1 per 100,000, higher in female than in male. The highest incidence was estimated in the age group between 35 and 44 years in male and age group between 25 and 29 years in female. Total burden of disease of MS was 1,394 DALY, comprised of 292 (21%) years of life lost and 1,101 (79%) years lived with disability. The mean age at onset of MS was 33 years old in men and 32 years old in female. Estimated duration of disease was 35 years in men and 40 years in female. Most of the DALY of MS occurred in the adult population between 25 and 54 years of age.

CONCLUSION

Although MS is a rare disease in Korea, most of the DALY arises from young people, which results in a major financial burden on the patient, family, health system and society.

Changing profile of 7,519 neurologic outpatients evaluated over 20 years

INTRODUCTION

There is scarce information on the demographic profile and diseases affecting neurologic outpatients.

METHODS

We evaluated 7,519 neurologic outpatients over 20 years at the outpatient clinic of the Department of Neurological Sciences, Hospital-Clínica Kennedy, Guayaquil, Ecuador.

RESULTS

Mean age was 48 ± 19.4 years, and 57.8% were women. Common reasons for consultation included headache (33.2%), focal deficits (10.7%), and seizures (9%). The most common categories of neurologic diseases were cerebrovascular (10.6%), degenerative (7.6%), and traumatic (7.1%). Diseases of uncertain/unknown etiology accounted for 50.2% of cases. Young patients were most often evaluated for headache and seizures, while elderly patients usually presented with focal deficits, movement disorders, or cognitive decline. We also found significant variations in the prevalence of neurologic diseases over the study years. While the prevalence of degenerative diseases increased from 5.7% in 1990-1994 to 10.2% in 2005-2009, that of infectious diseases steadily decreased from 3.7 to 2.1% over the study years.

CONCLUSION

There was a dynamic pattern of neurologic diseases over the years. Nowadays, distribution of neurologic symptoms and diseases in our population is more similar to that reported from the developed world than it was 20 years ago.

The epidemiology of multiple sclerosis in Latin America and the Caribbean: a systematic review

The incidence and prevalence of multiple sclerosis (MS) varies geographically as shown through extensive epidemiological studies performed mainly in developed countries. Nonetheless, scant data is available in Latin America and the Caribbean (LAC). The objective of this review is to assess epidemiological data of MS in LAC. We conducted a systematic review of published articles and gray literature from January 1995 to May 2011. Twenty-two studies met the inclusion criteria after full-text review. Incidence data were found in only three studies and ranged from 0.3 to 1.9 annual cases per 100,000 person-years. Prevalence was reported in 10 studies and ranged from 0.83 to 21.5 cases per 100,000 inhabitants. The most prevalent subtype of MS was the relapsing–remitting form (48% to 91% of the series). No data about mortality were found. This study showed low frequency for MS in LAC compared with North American and European countries. The role of environmental and genetic factors should be well studied, providing new insights about its etiology.

Human skin pigmentation, migration and disease susceptibility

Human skin pigmentation evolved as a compromise between the conflicting physiological demands of protection against the deleterious effects of ultraviolet radiation (UVR) and photosynthesis of UVB-dependent vitamin D(3). Living under high UVR near the equator, ancestral Homo sapiens had skin rich in protective eumelanin. Dispersals outside of the tropics were associated with positive selection for depigmentation to maximize cutaneous biosynthesis of pre-vitamin D(3) under low and highly seasonal UVB conditions. In recent centuries, migrations and high-speed transportation have brought many people into UVR regimes different from those experienced by their ancestors and, accordingly, exposed them to new disease risks. These have been increased by urbanization and changes in diet and lifestyle. Three examples-nutritional rickets, multiple sclerosis (MS) and cutaneous malignant melanoma (CMM)-are chosen to illustrate the serious health effects of mismatches between skin pigmentation and UVR. The aetiology of MS in particular provides insight into complex and contingent interactions of genetic and environmental factors necessary to trigger lethal disease states. Low UVB levels and vitamin D deficiencies produced by changes in location and lifestyle pose some of the most serious disease risks of the twenty-first century.

Prevalence of esophageal eosinophilia varies by climate zone in the United States

OBJECTIVES

The epidemiology of eosinophilic esophagitis (EoE) is rapidly evolving, and differences in climate could impact the prevalence of EoE. We aimed to examine the association between esophageal eosinophilia and climate zones in the United States.

METHODS

This was a cross-sectional study of esophageal biopsies from 2008 to 2010 in a large US pathology database. Cases were patients with esophageal eosinophilia; controls had normal esophageal biopsies. A Köppen-Geiger (K-G) climate class was assigned to each patient, and the association between case-control status and the main K-G climate type (tropical, arid, temperate, or cold) was assessed.

RESULTS

A total of 233,649 patients were included, 71,948 (30.8%) with normal esophageal biopsies and 9,995 (4.3%) with esophageal eosinophilia. Using the temperate zone as the referent and after multivariable analysis, the odds of esophageal eosinophilia were highest in the cold climate zone (odds ratio (OR)=1.39, 95% confidence interval (CI): 1.34-1.47), compared with the tropical zone (OR=0.87; 95% CI: 0.71-10.8) and the arid zone (OR=1.27; 95% CI: 1.19-1.36). Increased likelihood of EoE was also associated with increasing odds of being in the cold climate zone. Compared with patients with normal esophageal biopsies, patients with dysphagia, a clinical suspicion of EoE, no reflux or Barrett's esophagus, esophageal eosinophilia, and eosinophilic microabscesses had the highest adjusted odds of being in a cold climate zone (OR 2.02; 1.78-2.28).

CONCLUSIONS

Esophageal eosinophilia differs significantly between K-G climate zones, with the highest prevalence in the cold and arid zones. Geographical and climate patterns may help identify candidate antigens characteristic to high-prevalence areas to be targeted for future investigation.

Why does the north-south gradient of incidence of multiple sclerosis seem to have disappeared on the northern hemisphere?

The traditional view, based on numerous early studies and reviews, is that MS is particularly prevalent in temperate zones both on the northern and southern hemisphere. This uneven distribution of MS can be attributed to differences in genes and environment and their interaction. Diagnostic accuracy and case ascertainment are sources of error and have their shares in the geographical and temporal variations, and improvements in diagnostic accuracy and case ascertainment influence incidence- and prevalence rates. In addition the prevalence also depends on survival. With this meta-analysis we have focused on the trend in the incidence and sex ratio of MS through the last five decades, and we have analyzed the latitudinal distribution of MS incidence, based on a recent literature search. Our findings indicated that the prevalence and incidence rates had increased in almost all areas, but the previously reported latitudinal gradient of incidence of MS in Europe and North America could not be confirmed even when restricting the search to surveys published before 1980 or 1970. Conversely, the latitudinal gradient of prevalence rates seemed to be preserved. This apparent discrepancy can be explained by the circumstance that incidence estimates only depend on complete ascertainment for a relative short recent period of time, whereas reliable prevalence rates presuppose complete ascertainment decades back in time. A contributory explanation for the missing latitudinal gradient for incidence may be changes in environmental factors, levelling out differences in habits of life across Europe and North America, and, not least, that the interpretation of a latitudinal gradient in Europe was based primarily on prevalence studies and reviews. In addition, we observed in most regions a profound increase in female incidence of MS. The last observation should prompt epidemiological studies focusing on change in female life style.