Incidence Rate Of Multiple Sclerosis Research Articles

Acquiring new insights

Epidemiology studies have elucidated many key aspects of multiple sclerosis (MS). In adults, MS is more common in women and white individuals of Northern European heritage. The relative representation of sex, race, and heritage in pediatric MS is less well understood. MS is not thought to occur as a random event, but rather is considered a multifactorial disease influenced by both genetic and environmental factors, which can only be identified through the careful examination of disease in different populations over time.1 The study of MS in children offers a unique opportunity to explore the interplay between environmental, genetic, and hormonal factors in the developing immune and nervous systems. This process begins with identifying patients at risk—children presenting with acquired demyelinating syndromes (ADS), such as clinically isolated syndromes, including optic neuritis and transverse myelitis. Although MS and ADS are increasingly recognized in children, the incidence and prevalence are largely unknown. In this issue of Neurology ®, Langer-Gould et al.2 report incidence rates of MS and ADS for children in the United States for the first time. Using an electronic database of inpatient and outpatient records of Kaiser Permanente Southern California, a large health maintenance organization, the authors identified children presenting with demyelinating diseases through International Classification of Diseases (ICD)–9 codes …

Smoking and Increased Risk of Multiple Sclerosis: Parallel Trends in the Sex Ratio Reinforce the Evidence

Smoking behavior in industrialized nations has changed markedly over the second half of the 20th century, with diverging patterns in male and female smoking rates. We examined whether the female/male incidence of multiple sclerosis (MS) changed concomitantly with smoking, as would be expected if smoking truly increased MS risk. We identified relevant studies reporting male and female age-specific incidence of MS throughout the world using within-country birth cohorts as units of observation. We then correlated the male/female ratio of MS incidence in each birth cohort with the corresponding male/female ratios in smoking behavior obtained from national statistics. We also examined in depth the within-country trends of smoking and MS in Canada and Denmark, two populations in which statistics on MS are readily available. We show that, on the natural log scale, the gender ratio of MS is correlated with the gender ratio of smoking (r = 0.16; 95% confidence interval [CI]: 0.06, 0.26; p = 0.002). Additionally, we estimated an overall incidence rate ratio of 1.50 (95% CI: 1.17, 2.01) of MS for ever-smokers as compared with never-smokers. The trend in the gender ratio of smoking, however, is driven by a decline in smoking among men, rather than by an increase in women as observed for MS incidence. Our results are consistent with the hypothesis that smoking increases the risk of MS and explains in part the divergence in MS incidence rates in men and women. Some other factor, however, must account for the increasing MS incidence among women.

Prevalence and incidence of multiple sclerosis in Oppland County - a cross-sectional population-based study in a landlocked county of Eastern Norway

OBJECTIVES - We report the prevalence and incidence rates of multiple sclerosis (MS) in Oppland County, Norway. METHODS - Records from all patients diagnosed with MS at the two Oppland County hospitals, Gjøvik and Lillehammer during 1989-2001 were evaluated. In addition, all general practitioners in Oppland County reported their patients into the study. RESULTS - The age-adjusted prevalence rate of definite MS was 174.4/ 100 000 on the prevalence day 1 January 2002. When the probable cases were included, the prevalence rate rose to 185.6/100 000. The highest prevalence rates were detected in the northern mountain areas, thus corroborating the results from previous local surveys 30-50 years ago. The prevalence of MS was statistically significantly associated with climatic, socioeconomic and geographic variables in the county. The age-adjusted incidence of definite and probable MS in Oppland County was 6.6/100 000 during 1989-1993 increasing to 7.6/100 000 during 1994-1998. DISCUSSION - We found the highest prevalence rates of MS ever reported in Norway. Our findings indicate a possible influence of environmental factors.

Gender as a prognostic factor and its impact on the incidence of multiple sclerosis in Lorraine, France

We sought to identify (a) the change of incidence rates among gender from 1990 to 2002 from the LORSEP (Lorraine Multiple Sclerosis) population-based cohort, and (b) the role of gender as a predictive demographic factor of disability during the initial course of the disease among multiple sclerosis (MS) patients. The incidence rates of multiple sclerosis (MS) in Lorraine, France, have significantly increased in women, but not in men, from 1990 to 2002 but this increase in incidence of MS was not related to a better ascertainment of patients with mild disability. A total of 2871 MS patients were analyzed. For relapsing–remitting (RR) patients, a multivariate analysis showed that a shorter time to the assignment of an EDSS score of 3 and 4 was associated with the late onset MS, incomplete recovery from the first relapse and a high number of relapses during the first 5 years after the MS onset. Median times were not influenced by gender or by time between the first two relapses. The data were very different for the time between the assignment of scores of 4 and 6, since the median times were not influenced by any of the predicting variables.

Population-Based Epidemiological Study of Neurological Diseases in Taiwan: I. Creutzfeldt-Jakob Disease and Multiple Sclerosis

Background: The purpose of the study is to investigate the epidemiology of Creutzfeldt-Jakob disease (CJD) and multiple sclerosis (MS) in Taiwan. Methods: Cases of CJD and MS were identified from the National Health Insurance Research Database from January 2000 to December 2005. Age- and sex-specific incidences of these diseases were estimated by dividing the incidence number by population data obtained from the Department of Statistics, Ministry of the Interior. Results: During the study period, 79 cases of CJD, 41 women and 38 men, were identified. The average annual incidence rate was 0.63/million. Most cases were older than 60 years. There were 1,262 cases of MS. The male-to-female ratio was 0.4. The average annual incidence rate was 0.79/100,000. The incidence reached a peak at the age group of 40–60 years for females and at the age group of over 55 years for males. The prevalence of MS was 2.96/100,000 in 2005, which is higher than those of previous studies in Taiwan. Conclusions: The annual incidence rate of CJD in Taiwan is lower than in western countries. The annual incidence rate and prevalence of MS in Taiwan are low. The prevalence of MS in Taiwan increased in recent decades.

Temporal trends in the incidence of multiple sclerosis

Multiple sclerosis (MS) has been traditionally considered to be more frequent in women and in regions more distant from the equator. However, recent reports suggest that the latitude gradient could be disappearing and that the female-to-male ratio among patients with MS has increased in the last decades. We have conducted a systematic review of incidence studies of MS to assess the overall incidence of MS and explore possible changes in the latitude gradient and the female-to-male ratio over time. Systematic review of incidence studies of MS published in Medline between 1966 and February 2007. Age- and sex-specific incidence rates were collected from eligible publications. We computed age-adjusted rates using the world population as standard, and assessed differences in rates according to latitude and period of case ascertainment. Additionally, we evaluated the association between period of case ascertainment and the female-to-male ratio. The overall incidence rate of MS was 3.6 cases per 100,000 person-years (95% CI 3.0, 4.2) in women and 2.0 (95% CI 1.5, 2.4) in men. Higher latitude was associated with higher MS incidence, though this latitude gradient was attenuated after 1980, apparently due to increased incidence of MS in lower latitudes. The female-to-male ratio in MS incidence increased over time, from an estimated 1.4 in 1955 to 2.3 in 2000. The latitude gradient present in older incidence studies of multiple sclerosis (MS) is decreasing. The female-to-male MS ratio has increased in the last five decades.

Incidence of multiple sclerosis in the United Kingdom

Existing data on the incidence of multiple sclerosis (MS) in the UK have some limitations. Few studies have reported age- and sex-specific incidence rates of MS, and none of those is based on a large sample of the general population. Further, no published reports have provided age- and sex-specific incidence rates of MS by clinical course from onset. To estimate the age- and sex-specific incidence rate and lifetime risk of multiple sclerosis, we identified all new cases of MS during the period 1993-2000 in the General Practice Research Database, which includes health information on over three million Britons. Based on 642 incident cases, incidence rates of MS adjusted to the world population were 7.2 (95 % CI 6.5, 7.8) in women and 3.1 (95 % CI 2.6, 3.5) in men. The incidence of MS with relapsing-remitting onset was higher in women than in men (incidence rate ratio 2.5, 95% CI 2.1, 3.1), but there were no sex differences for primary-progressive MS (incidence rate ratio 1.1, 95% CI 0.7, 1.8). The estimated lifetime risk from birth of receiving an MS diagnosis was 5.3 per 1,000 in women and 2.3 per 1,000 in men. These results confirm the relatively high incidence of MS in the UK and show marked differences in the sex-specific pattern of MS incidence by clinical course from onset.

Prevalence of multiple sclerosis in Santiago de Compostela (Galicia, Spain)

Introduction Multiple sclerosis (MS) is the most common central nervous system disease in young adults, and one of the leading causes of disability in this age group. Objectives To establish the prevalence and incidence of MS in Santiago de Compostela (Spain). Material and methods We performed a prospective, case-finding study on >90188 inhabitants, from 1 January 1998 to 15 September 2003, selected as day of prevalence. Sources of information were the University Clinical Hospital of Santiago, the hospitals and private clinics of the city, rehabilitators, pediatricians, ophthalmologists, psychiatrists, neurosurgeons, specialists in internal medicine, primary care physicians, association of patients of MS, social services and nongovernmental and religious associations. Informative days were programmed for the susceptible population, and campaigns were carried out in the media. All patients with Poser diagnostic criteria for MS, on the census of Santiago de Compostela as of 15 September 2003, were included in the study. Results On the day of prevalence, 71 patients with MS were registered on the census of Santiago de Compostela, therefore, the prevalence was 79 cases per 100000 inhabitants. The incidence of the disease in the study period was 5.3 cases per 100000 inhabitants and year. Conclusions The prevalence and incidence rates of MS found in Santiago de Compostela are the highest reported, to date, in Spain. Multiple Sclerosis 2007; 13: 262–264. http://msj.sagepub.com

The epidemiology of multiple sclerosis in Europe

Multiple sclerosis (MS) is a chronic and potentially highly disabling disorder with considerable social impact and economic consequences. It is the major cause of non-traumatic disability in young adults. The social costs associated with MS are high because of its long duration, the early loss of productivity, the need for assistance in activities of daily living and the use of immunomodulatory treatments and multidisciplinary health care. Available MS epidemiological estimates are aimed at providing a measure of the disease burden in Europe. The total estimated prevalence rate of MS for the past three decades is 83 per 100,000 with higher rates in northern countries and a female:male ratio around 2.0. Prevalence rates are higher for women for all countries considered. The highest prevalence rates have been estimated for the age group 35-64 years for both sexes and for all countries. The estimated European mean annual MS incidence rate is 4.3 cases per 100,000. The mean distribution by disease course and by disability is also reported. Despite the wealth of epidemiological data on MS, comparing epidemiological indices among European countries is a hard task and often leads only to approximate estimates. This represents a major methodological concern when evaluating the MS burden in Europe and when implementing specific cost-of-illness studies.

Possible increasing risk of multiple sclerosis in Catania, Sicily

To update prevalence and incidence rates of multiple sclerosis (MS) in Catania, Italy during 1990 to 1999 and evaluate their temporal profiles to assess a possible increase in the MS risk in our study population. We studied the frequency of MS in Catania, Italy (population of 313,110 as reported in the 2001 census). The primary sources for the case ascertainment were the neurologic and motor-rehabilitation departments, the MS centers, the Italian MS Association, private neurologists, and family doctors. We considered as prevalent and incident cases all patients who satisfied Poser's criteria for clinically definite MS (CDMS), laboratory-supported definite MS (LSDMS), clinically probable MS (CPMS), and laboratory-supported probable MS (LSPMS). We found 288 subjects with MS who had onset of disease before December 31, 1999 (prevalence day) in a population of 313,110 inhabitants. The prevalence rate was 92.0/100,000 (95% CI 81.8 to 103.2) and was higher in women (102.4/100,000) than in men (80.4/100,000). The age-specific prevalence showed a peak in the group aged 35 to 44 years (208.2/100,000). From 1990 to 1999, 155 patients with MS had the clinical onset of the disease. The mean annual incidence was 4.7/100,000 (95% CI 4.0 to 5.5). Age-specific incidence showed a peak in the group aged 25 to 34 years (11.7/100,000). Mean annual incidence for 5-year intervals increased from 3.9/100,000 during 1990 to 1994 to 5.5/100,000 during 1995 to 1999. Prevalence and incidence rates of multiple sclerosis have further increased during the last decade.

Familial Risk of Multiple Sclerosis: A Nationwide Cohort Study

Multiple sclerosis (MS) is known to accumulate within families. The magnitude of the familial risk, however, remains uncertain. Using a nationwide MS register and other national registers, the authors estimated relative and absolute risks of MS in a population-based cohort that included 19,615 first-degree relatives of 8,205 Danish MS patients followed from 1968 to 1997. The ratio of observed to expected numbers of MS cases served as the measure of the relative risk of MS. Lifetime risks of MS in first-degree relatives were estimated as the product of the relative risk and the national lifetime risk of MS. Overall, first-degree relatives had a sevenfold increased risk of MS (relative risk=7.1, 95% confidence interval: 5.8, 8.8) (n=90) compared with the background population. By modeling the individual incidence rate of MS as the sum of a familial component and a sporadic risk component, the familial excess lifetime risk was found to be 2.5% (95% confidence interval: 2.0, 3.2) among first-degree relatives of MS patients, irrespective of the gender of the proband and the relative. This percentage should be added to a sporadic absolute risk in the general population of 0.5% in women and 0.3% for men. Spouses of MS patients did not experience an increased risk of MS, suggesting no major role for environmental factors acting in adulthood.

Multiple Sclerosis in Southern Europe: Monreale City, Italy

Background: Several follow-up studies showed increasing prevalence and incidence rates for multiple sclerosis (MS). Objective: To ascertain, throughout a follow-up study, the incidence and prevalence of MS in the city of Monreale, Sicily, southern Italy. Methods: We calculated crude and age- and sex-specific prevalence rates on December 31, 2000, and determined incidence rates for the period January 1, 1992 to December 31, 2000. Results: The prevalence of MS was 71.2 per 100,000 population (48,5/100,000 in men; 93,0/100,000 in women). The incidence rate of MS for the period 1992–2000 was 4.0/100,000 per year. Conclusion: This study showed a nonsignificant increase in MS incidence rates in Monreale city for 1992–2000 compared to 1981–1991. Prevalence rates were similar to those of the previous follow-up study. Intervals between onset of symptoms and diagnosis seemed shorter than in prior studies. There is no evidence that the high prevalence and incidence rates have changed in this interval but numbers are too small for firm statements. These findings indicate that in Monreale city MS prevalence is stable and confirm Sicily as a high-risk area for MS.

Incidence and prevalence of multiple sclerosis in Olmsted County, Minnesota, 1985-2000.

Epidemiologic data for multiple sclerosis (MS) in Olmsted County, MN, have been recorded for almost 100 years and have indicated that the increasing prevalence rate was likely due in part to an increasing incidence rate. All cases of MS diagnosed from 1985 to 2000 were identified using the centralized diagnostic index at the Mayo Clinic and the Rochester Epidemiology Program Project, a shared database of all medical practitioners in the county. Patients were required to have established residency at least 1 year prior to diagnosis of MS. Results were also age- and sex-adjusted to control for shifts in the population structure. The raw prevalence of MS was determined to be 177 per 100,000 on December 1, 2000, and the raw incidence rate was 7.5 per 100,000 person-years at risk from 1985 to 2000. After age and sex adjustment to a common population, these prevalence and incidence rates of MS appear to have been stable rather than increasing over the past 20 years.

The Frequency of Multiple Sclerosis in Jewish and Arab Populations in Greater Jerusalem

A comparison of the incidence rate (IR) and the prevalence rate (PR) of multiple sclerosis (MS) in subgroups of the same ethnic origin, but born and living in different geographical areas, may delineate the relationship between environmental and genetic risk factors for MS. Previous epidemiological studies of MS in Israel did not include the Arab population and used diagnostic criteria that did not include MRI findings. Therefore, we studied the age-adjusted IR and PR of MS in a more recent sample in different population groups, including Arabs, of Greater Jerusalem. We found that the PR of MS in Israeli Jews is higher than previously described. Furthermore, the PR was significantly lower among immigrant Jews from Asia/Africa (A/A) than among native-born Jews of Asian/African origin (I-A/A). Since these groups have similar genetic susceptibilities to MS, the higher PR in the latter is probably due to environmental factors. Our study does not support the effect of latitude on the risk of developing MS since no difference in the PR was found between immigrant Jews from Europe/America (E/A) and native-born Jews of European/American origin (I-E/A). Among Arabs, the PR was similar to that among A/A. Therefore, we hypothesized similarity in environmental etiologic factors for MS between the countries of origin of A/A immigrants and of Arabs communities in Greater Jerusalem. The IR of I-E/A was higher than that of I-A/A and Arabs, although this difference did not reach statistical significance.

Incidence (1988–97) and prevalence (1997) of multiple sclerosis in Västerbotten County in northern Sweden

Objective: To investigate the incidence and prevalence of multiple sclerosis in Västerbotten County in northern Sweden. Methods: Multiple sources were used in the case identification process. Follow up interviews with...

Multiple sclerosis complexity in selected populations: the challenge of Sardinia, insular Italy.

Several lines of evidence indicate a genetic contribution to multiple sclerosis (MS) both in terms of predisposition to the disease and of immunological mechanisms which are known to play crucial roles in MS pathogenesis. The presence of high- and low-risk areas for MS in neighbouring regions supports the theory that MS predisposition is influenced by a complex interaction of genetic and environmental factors. Therefore, the use of genetically homogeneous and geographically isolated populations becomes an increasing requirement to reduce biasing biological variables. Sardinians fulfil these conditions well because of their different phylogeny from Europeans and the unique selective pressures which shaped their genome. Sardinians display amongst the highest MS prevalence rates world-wide and increasing MS incidence rates over time. Also, MS in Sardinia is linked to distinct human leucocyte antigen (HLA) alleles and associated to different patterns of cytokine production from lymphoid cells of different HLA subtypes. In this context, recent findings and future perspectives on the peculiarities of Sardinian MS concerning genetic, immunological and epidemiological aspects are presented. So far, our results indicate that variations at the level of territorial distribution and HLA-association are present which render MS heterogeneous even in this ethnically homogeneous population.

The natural history of untreated multiple sclerosis in Iceland. A total population-based 50 year prospective study

The incidence of multiple sclerosis (MS) has reportedly increased over time; however, change in MS incidence has not been rigorously assessed globally.We followed the guidelines for the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) statement. Two independent reviewers systematically searched Scopus, PubMed and Web of Science for peer-reviewed publications in English from 1 January 1985 to 24 September 2020 reporting MS incidence for at least two contiguous five-year periods with clearly-defined case ascertainment. The outcome was change in MS incidence rate according to geographical region.We identified 64 papers providing 65 regional estimates (including three paediatric-onset MS) across 24 countries covering ∼3% of the world's population (in 2000/1 or closest available total population for the entire country), with quality (adapted Newcastle-Ottawa Scale) ranging from sufficient to good. Studies were mainly from Italy (n=14 including San Marino), Norway (n=10) or Canada (n=9), with no studies in the Africa or South-East Asia regions. Of the 62 whole-of-population estimates, MS incidence rates: significantly increased in 38 (61%), significantly decreased in 13 (21%) and remained stable in 11 (18%). In the paediatric-onset studies, MS incidence was stable in two (67%) and increased in one (33%). Many estimates derived from only selected (often small) regions of a country. For 42 (68%) of the whole-of-population estimates (and two of the paediatric-onset estimates) a consistent case definition or diagnostic criteria over the entire study period was explicitly reported. Across the n=9 whole-of-population estimates based on a consistent case definition for the duration of the study period, and including a substantial proportion of the population of a country (≥one-third), incidence rates were stable in n=3, increased in n=3 and decreased in n=3. Studies using a consistent case definition covered ∼2.7% of the global population; incidence rates were stable in 0.9% of the global population, decreased in studies covering 1%, and increased in those covering 0.8% of the global population.The studies reporting change in MS incidence rate over time were limited by world region and the proportion of the global population covered. Although by number of studies, the predominant pattern was increasing MS incidence, in studies where a consistent case definition was used across the duration of the study and with high population coverage, no predominant pattern of MS incidence was evident.

The influence of oral contraceptives on the risk of multiple sclerosis

To examine the risk of multiple sclerosis in users of combined oral contraceptives. Cohort study conducted between 1968 and 1996 using diagnostic data supplied by general practitioners General practices throughout the United Kingdom. Royal College of General Practitioners' Oral Contraception Study cohort of initially 46,000 women recruited during the late 1960s. Directly standardised incidence rates of multiple sclerosis were calculated for current, former and never-users of oral contraceptives using first ever cases of multiple sclerosis reported by the general practitioners. The standardisation variables were age, parity, social class and smoking history. Five-year survival rates in the different contraceptive groups were calculated using standard life table techniques. One hundred and fourteen first ever cases of multiple sclerosis had been reported by November 1996 during 564,000 woman-years of observation. The incidence rate in both current and former users was not materially different to that in never-users. Although based on limited evidence there was no suggestion that the five-year survival was affected by a woman's use of combined oral contraceptives. These findings do not suggest a greatly elevated risk of multiple sclerosis during, or after, use of combined oral contraceptives.

Incidence of multiple sclerosis in Denmark 1948-1982: a descriptive nationwide study.

The incidence rates of multiple sclerosis (MS) in Denmark were estimated as a result of a continuous nationwide epidemiological survey since 1948 by the Danish Multiple Sclerosis Registry (DMSR). Among cases notified to the DMSR, 6,478 met the diagnostic criteria and had onset of MS from 1948 through 1982. The crude annual incidence rate was 4.45/100,000 and the lifetime cumulative incidence rate was 0.32%. The female/male ratio was 1.37:1. Crude incidence rates declined during the period 1952-1967. After 1967 the incidence seemed to rise again but in an irregular pattern. The decline in incidence involved only cases up to the age of 35. The subsequent increase was most marked in females and in the age groups over 45 years.

Frequency of Multiple Sclerosis in Valle d'Aosta, 1971–1985

According to studies done before 1980, the multiple sclerosis (MS) prevalence rate in Italy ranged from 7.2 to 27.1 cases per 100,000 inhabitants. More recent work has consistently put the MS prevalence rate to over 30 cases per 100,000 inhabitants. If these recent data are confirmed in the future, Italy can no longer be regarded as a country at low risk for MS, but must be included among the medium-high risk countries of continental Europe. We report the results of a prevalence and incidence survey conducted in Valle d'Aosta, a region whose special features make it an excellent epidemiological model. The mean annual incidence was 2.1 and on December 31, 1985, the prevalence was 39 cases per 100,000 inhabitants. These results confirm that the incidence and prevalence rate of MS in Valle d'Aosta is close to that of areas at high-risk for MS.