Geographical Heterogeneity of Multiple Sclerosis Prevalence in France

Disentangling Multiple Sclerosis heterogeneity in the French territory among genetic and environmental factors via Bayesian heritability analysis

BACKGROUND

This study aimed to investigate the factors contributing to the variability of Multiple Sclerosis (MS) among individuals born and residing in France. Geographical variation in MS prevalence was observed in France, but the role of genetic and environmental factors in explaining this heterogeneity has not been yet elucidated.

METHODS

We employed a heritability analysis on a cohort of 403 trios with an MS-affected proband in the French population. This sample was retrieved from REFGENSEP register of MS cases collected in 23 French hospital centers from 1992 to 2017. Our objective was to quantify the proportion of MS liability variability explained by genetic variability, sex, shared environment effects, region of birth and year of birth. We further considered gene x environment (GxE) interaction effects between genetic variability and region of birth. We have implemented a Bayesian liability threshold model to obtain posterior distributions for the parameters of interest adjusting for ascertainment bias.

RESULTS

Our analysis revealed that GxE interaction effects between genetic variability and region of birth represent the primary significant explanatory factor for MS liability variability in French individuals (29 % [95 %CI: 5 %; 53 %]), suggesting that additive genetic effects are modified by environmental factors associated to the region of birth. The individual contributions of genetic variability and region of birth explained, respectively, ≈15 % and ≈16 % of MS variability, highlighting a significantly higher MS liability in individuals born in the Northern regions compared to the Southern region. Overall, the joint contribution of genetic variability, region of birth, and their interaction was then estimated to explain 65 % [95 %CI: 35 %; 92 %] of MS liability variability. The remaining proportion of MS variability is attributed to environmental exposures associated with the year of birth, shared within the same household, and specific to individuals.

CONCLUSION

Overall, our analysis highlighted the interaction between genetic variability and environmental exposures linked to the region of birth as the main factor explaining MS variability within individuals born and residing in France. Among the environmental exposures prevalent in the Northern regions, and potentially interacting with genetic variability, lower vitamin D levels due to reduced sun exposure, higher obesity prevalence and higher pollution levels represent the main risk factors in influencing MS risk. These findings emphasize the importance of accounting for environmental factors linked to geographical location in the investigation of MS risk factors, as well as to further explore the influence of GxE interactions in modifying genetic risk.

Risk of cancer with immunosuppressants compared to immunomodulators in multiple sclerosis: A nested case-control study within the French nationwide claims database

PURPOSE

The objective was to compare the risk of malignancies in real-world settings between exclusive immunosuppressant (IS) and immunomodulator (IM) use in multiple sclerosis (MS).

METHODS

A nested case-control study was designed within a new-user cohort of all patients with MS who initiated a first IM or IS between 2008 and 2014, and without cancer history, using the information of the SNDS nationwide French claims database. Incident cancer cases were matched with up to six controls on year of birth, sex, initiation date, and disease risk score of cancer. A conditional logistic regression (odds ratio [95% confidence interval]) was used to compare exclusive IS versus IM use during follow-up and according to three use durations.

RESULTS

From 28 720 newly treated patients with MS, 407 incident cancers were observed during the follow-up with 2324 matched controls. A significant increase in cancer risk was observed for IS compared with IM (1.36 [1.05, 1.77]), with similar increases for the first 2 years of use but not for ≥2 years (1.06 [0.65, 1.75]). Similar increase was also observed for IS with indications other than MS (1.37 [1.04, 1.81]) but not for IS indicated only in MS (1.03 [0.45, 2.34]).

CONCLUSIONS

Compared with IM, a 37% increase in cancer risk was observed for IS with indications other than MS and used for a short duration (≤2 years) but not for IS indicated only in MS. The absence of risk for prolonged exposure of IS with indications other than MS is not in favor of a causal relation with these drugs.

Age-period-cohort analysis of the incidence of multiple sclerosis over twenty years in Lorraine, France

Multiple sclerosis (MS) is a neurodegenerative disease of the central nervous system. An increase in MS incidence over time is reported in several regions of the world. We aimed to describe the evolution of the annual MS incidence in the Lorraine region, France, from 1996 to 2015 and to analyze potential components of a possible change by a temporal effect of age at MS onset, MS onset period, and birth cohort, overall and for each sex. Cases were identified from ReLSEP, a population-based registry of MS cases living in Lorraine, northeastern France, with MS onset between 1996 and 2015. Age-period-cohort modeling was used to describe trends in MS incidence. Annual age- and sex-standardized incidences were relatively stable: 6.76/100 000 population (95%CI [5.76-7.91]) in 1996 and 6.78/100 000 (95%CI [5.72-7.97]) in 2015. The incidence ratio between women and men was 2.4. For all time periods, the peak incidence occurred between ages 25 and 35 years. Age-period-adjusted cohort and age-cohort-adjusted period analyses did not reveal a period or cohort effect. The incidence of MS remained stable over the study period in Lorraine, and we could not identify any particular effect of disease onset period or birth period on this evolution.

Multiple sclerosis incidence rate in southern Iran: a Bayesian epidemiological study

Background

Multiple Sclerosis (MS) remains to be a public health challenge, due to its unknown biological mechanisms and clinical impacts on young people. The prevalence of this disease in Iran is reported to be 5.30 to 74.28 per 100,000-person. Because of high prevalence of this disease in Fars province, the purpose of this study was to assess the spatial pattern of MS incidence rate by modeling both the associations s of spatial dependence between neighboring regions and risk factors in a Bayesian Poisson model, which can lead to the improvement of health resource allocation decisions.

Method

Data from 5468 patients diagnosed with MS were collected, according to the McDonald’s criteria. New cases of MS were reported by the MS Society of Fars province from 1991 until 2016. The association between the percentage of people with low vitamin D intake, smoking, abnormal BMI and alcohol consumption in addition to spatial structure in a Bayesian spatio-temporal hierarchical model were used to determine the relative risk and trend of MS incidence rate in 29 counties of Fars province.

Results

County-level crude incidence rates ranged from 0.22 to 11.31 cases per 100,000-person population. The highest relative risk was estimated at 1.80 in the county of Shiraz, the capital of Fars province, while the lowest relative risk was estimated at 0.11 in Zarindasht county in southern of Fars. The percentages of vitamin D supplementation intake and smoking were significantly associated with the incidence rate of MS. The results showed that 1% increase in vitamin D supplementation intake is associated with 2% decrease in the risk of MS and 1% increase in smoking is associated with 16% increase in the risk of MS.

Conclusion

Bayesian spatio-temporal analysis of MS incidence rate revealed that the trend in the south and south east of Fars province is less steep than the mean trend of this disease. The lower incidence rate was associated with a higher percentage of vitamin D supplementation intake and a lower percentage of smoking. Previous studies have also shown that smoking and low vitamin D, among all covariates or risk factors, might be associated with high incidence of MS.

Clinical practice patterns in multiple sclerosis management: Mexican consensus recommendations

BACKGROUND

Multiple sclerosis affects more than 2 million people. Clinical decisions are performed under evidence-based medicine. The appearance of new disease-modifying therapies and changes in diagnostic criteria complicates the decision-making process in clinical practice.

OBJECTIVES

To characterize the criteria for radiologically isolated syndrome (RIS), clinically isolated syndrome (CIS), and relapsing-remitting multiple sclerosis (RRMS) by Mexican neurologists in a real-world setting.

METHODS

A two-round modified Delphi method (RAND/UCLA) was applied.

RESULTS

In RIS, LP, spinal cord MRI and VEP should be included in diagnostic testing; DMT initiation is not necessary. A follow-up MRI within 3 months are recommended. In CIS, corticosteroid therapy should be initiated at first relapse; both simple and Gd-enhanced MRI is mandatory. LP, selective blood tests, and NMO-IgG/AQP4 antibodies should be performed as complementary. IFN beta or GA were the most suitable DMTs for treating high-risk CIS. Patients with RRMS should begin with DMT at diagnosis, include a follow-up MRI if a patient had 2 relapses within 6 months. GA and oral DMTs are the most eligible DMTs for mild RRMS. Monoclonal antibodies-based therapy is chosen when disability is present. Radiological criteria for switching DMT included >1 Gd+ lesion and >2 new T2 lesions.

CONCLUSIONS

Although many coincidences, there are still many hollows in the medical attention of MS in Mexico. This consensus recommendation could be helpful to implement better evidence-based recommendations and guidelines in a real-world setting.

Use of geographical information systems in multiple sclerosis research: A systematic scoping review

INTRODUCTION

Geographical information system (GIS) and spatial analysis have an emerging role in the understanding and management of health-related outcomes. However, there is a knowledge gap about the extent to which GIS has supported multiple Sclerosis (MS) research. Therefore, this review aimed to explore the types of GIS applications and the complexity of their visualisation in MS research.

METHODS

A systematic scoping review was conducted based on York's five-stage framework. PubMed, Scopus and Web of Science were searched for relevant studies published between 2000 and 2020 using a comprehensive search strategy based on the main concepts related to GIS and MS. Grounded, inductive analysis was conducted to organize studies into meaningful application areas. Further, we developed a tool to assess the visualisation complexity of the selected papers.

RESULTS

Of 3,723 identified unique citations, 42 papers met our inclusion criteria for the final review. One or more of the following types of GIS applications were reported by these studies: (a) thematic mapping (37 papers); (b) spatial cluster detection (16 papers); (c) risk factors detection (16 papers); and (d) health access and planning (two papers). In the majority of studies (88%), the score of visualisation complexity was relatively low: three or less from the range of zero to six.

CONCLUSIONS

Although the number of studies using GIS techniques has dramatically increased in the last decade, the use of GIS in the areas of MS access and planning is still under-researched. Additionally, the capacity of GIS in visualising complex nature of MS care system is not yet fully investigated.

Retrospective evaluation of regional telemedicine team meetings for multiple sclerosis (MS) patients: Experience from the Caen MS expert center in Normandy, France

INTRODUCTION

Multiple sclerosis (MS) is a demyelinating disease requiring multidisciplinary care coordination. Recent development of diagnosis criteria and disease modifying treatments have encouraged the setup of regional team meetings by MS expert centers, known as CRC Sep, to improve the quality of care provided to patients with complex cases. The CRC Sep in Caen initiated regional telemedicine meetings named Télé-SEP, operating since 2016. The objective of this study was to evaluate the Télé-SEP used by neurologists, on MS patient care management in Normandy.

METHODS

An internal ex-itinere evaluation was conducted with a retrospective descriptive observational study from July 2016 to June 2018. The Télé-SEP meetings were organized with 41 neurologists using a regional telemedicine platform (Therap-e). Data were collected from online records and a declarative voluntary survey. Twenty indicators were classified in the categories: volume of activity, clinical profile, quality and impact.

RESULTS

Fifteen meetings were organized with a median of 13 senior neurologists. One hundred forty MS cases were discussed and there was a 33% increase in the second year of Télé-SEP. Median patient age was 44 years with a 72-month median length of disease. Most patient cases required second-line treatment. Relapsing remitting MS was diagnosed in 51.4% of cases. Télé-SEP satisfaction rate was 4.5/5 and 96% of neurologists applied the medical decisions and recommendations given in the meetings.

CONCLUSION

Without Télé-SEP, 54.5% of patients would have been referred to a physical expert consultation in the CRC Sep. This study showed the feasibility and relevance of regional telemedicine team meetings for MS cases in the Normandy region.

The Administrative Prevalence of Multiple Sclerosis in Greece on the Basis of a Nationwide Prescription Database

Objective: To estimate current prevalence of multiple sclerosis (MS) in Greece using administrative data from the nationwide medicine prescription database.

Methods: Prescription records of a 24-month period (June 2017–May 2019) were analyzed in order to identify cases of MS. Sex, age, and place of residence were recorded for each identified case. Prevalence of MS was calculated based on the updated records of the Greek population according to Hellenic Statistical Authority.

Results: The 2-year cumulative period prevalence of MS was estimated to 197.8 per 100,000 (95% CI 197.6–198.0). In total, 21,218 patients (65.8% female) were identified. During this period, the prevalence of MS was 138.7 per 100,000 (95% CI 138.4–139.0) in men and 253.6 per 100,000 (95% CI 253.3–254.1) in women. Prevalence was higher in the 45–49 age group in both sexes. Analysis of the place of residence revealed higher prevalence in the Attica region and Western Greece while lower prevalence was observed in Northern Greece. No north–south latitude gradient was detected. Point prevalence on 1 January 2019 was calculated to 188.9 per 100,000 (95% CI 188.7–189.1). Regarding treatment, 73.1% of the identified cases received at least once a Disease Modifying Drug.

Conclusions: According to this national-level study conducted in Greece, estimated prevalence of MS was found to be similar to those of other European countries. Heterogeneity of MS prevalence across the country was observed and needs further investigation.

Rising prevalence of multiple sclerosis in Saudi Arabia, a descriptive study

BACKGROUND

In 2015, the first nationwide, multicenter Multiple Sclerosis (MS) registry was initiated in the Kingdom of Saudi Arabia (KSA) mainly with an objective to describe current epidemiology, disease patterns, and clinical characteristics of MS in Saudi Arabia. This article aimed to report initial findings of the registry and regional prevalence of MS.

METHOD

In 2015, a national MS registry was launched in KSA to register all MS patient with confirmed diagnosis according to the 2010 McDonald Criteria. The registry aimed to identify and recruit all healthcare facilities treating MS patients in the Kingdom, and collect data such as demographics, clinical characteristics (disease onset, diagnosis, presentation of symptoms at onset, disease course, relapse rate, and disability measures), family history, and treatments. All the included sites have obtained IRB/EC approvals for participating in the registry. Currently, the registry includes 20 hospitals from different regions across the Kingdom. The Projected prevalence was calculated based on the assumption that the number of diagnosed MS cases in participating hospitals (in each region) is similar to the number of cases in remaining nonparticipant hospitals in the same region.

RESULTS

As of September 2018, the registry has included 20 hospitals from the different regions across the Kingdom and has collected comprehensive data on 2516 patients from those hospitals, with median age 32 (Range: 11-63) and 66.5% being females. The reported prevalence of MS for those hospitals was estimated to be 7.70/100,000 population and 11.80/100,000 Saudi nationals. Based on the assumption made earlier, we projected the prevalence for each region and for the country as a whole. The overall prevalence of MS at the country level was reported to be 40.40/100,000 total population and 61.95/100,000 Saudi nationals. Around 3 out of every 4 patients (77.5%) were 40 years of age or younger. Female to male ratio was 2:1. The prevalence was higher among females, young and educated individuals across all five regions of Saudi Arabia.

CONCLUSION

The prevalence of MS has significantly increased in Saudi Arabia but is still much lower than that in the western and other neighboring countries like Kuwait, Qatar, and the UAE. However, compared to the past rates, Saudi Arabia's projected prevalence of MS through this national study is 40.40/100,000 population, putting the Kingdom above the low risk zone as per Kurtzke classification. The projected prevalence was estimated to be much higher among Saudi nationals (61.95/100,000 Saudi-nationals). The prevalence was higher among female, younger and educated individuals. Further studies are needed to assess the risk factors associated with increased prevalence in Saudi Arabia.

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.

Hypothesis: Multiple sclerosis is caused by three-hits, strictly in order, in genetically susceptible persons

Multiple Sclerosis is a chronic, progressive and debilitating neurological disease which, despite extensive study for over 100 years, remains of enigmatic aetiology. Drawn from the epidemiological evidence, there exists a consensus that there are environmental (possibly infectious) factors that contribute to disease pathogenesis that have not yet been fully elucidated. Here we propose a three-tiered hypothesis: 1) a clinic-epidemiological model of multiple sclerosis as a rare late complication of two sequential infections (with the temporal sequence of infections being important); 2) a proposal that the first event is helminthic infection with Enterobius Vermicularis, and the second is Epstein Barr Virus infection; and 3) a proposal for a testable biological mechanism, involving T-Cell exhaustion for Epstein-Barr Virus protein LMP2A. We believe that this model satisfies some of the as-yet unexplained features of multiple sclerosis epidemiology, is consistent with the clinical and neuropathological features of the disease and is potentially testable by experiment. This model may be generalizable to other autoimmune diseases.