Multiple sclerosis in Oslo, Norway: prevalence on 1 January 1995 and incidence over a 25-year period

The Oslo Multiple Sclerosis (MS) Registry was established in 1990, and this is the first report on the prevalence and incidence of MS in the city of Oslo, Norway. The prevalence rate of definite MS on 1 January 1995 was 120.4/10(5). Inclusion of patients of native Norwegian ancestry only and exclusion of non-Norwegian immigrants yielded a prevalence rate of 136.0/10(5). A similar prevalence rate (136.5/10(5)) was found when patients and immigrants from the other Nordic countries (Finland, Sweden, Denmark) were included. Segregation of the native Norwegian patients according to the counties where they were born showed no significant differences except for a disproportionate increase of patients born in the inland county of Oppland. A total of 794 cases were resident in Oslo at the time of a diagnosis of definite MS in the period 1972-99. The crude average annual incidence rate for each 5-year period, between 1972 and 1996, increased significantly from 3.7/10(5) in the 1972-76 to 8.7/10(5) in the 1992-96 period. The increase was more marked in relapsing-remitting (RR) than in primary progressive disease and in female cases.     

The organisation of health care and epidemiology of multiple sclerosis in France

STATE OF THE ART: According to the available previous studies, France is considered a zone of medium to high risk of multiple sclerosis (MS) with an estimated overall prevalence of at least 50/100,000 inhabitants, incidence rates were stable in some areas but increased over time in others and a strong ethnic effect on the incidence, clinical presentation, and course of MS is reported. RESULTS: Based on two health insurance survey the prevalence has been deduced. At January 1, 2003 from the data of agricultural health insurance the prevalence is evaluated at 65.5/100,000 inhabitants (95p.cent CI=62.5-67.5) with a gradient of North East towards South-West. The data from the national health insurance were very near. During the period 2000-2004, recent studies in Auvergne and Brittany demonstrated an annual incidence comprising between 4.2 and 5.1 per 100,000 inhabitants. In Lorraine, in a large population-based study, in December 31, 2004 the prevalence rate was 120/100,000 (95p.cent CI: 119 to 121). During the period 1990-2002, the average age- and sex-adjusted annual incidence rate was 5.5/100,000 (95p.cent CI: 4.4-6.6). In Lorraine, we found that the age-adjusted incidence rate increased during the period 1990-2002. The incidence of MS in women increased, whereas that in men did not change significantly during this period. Similarly, in Norway, North Ireland and Denmark, the incidence among women increased the most. The clinical features of MS were compared in 211 North Africans patients and 2 945 Europeans patients in two French MS centres (Lorraine and Nice) with definite MS according to McDonald's criteria. The course of MS appears more aggressive in North Africans than in Europeans patients. For example, we demonstrated a shorter time to reach the Expanded Disability Status Scale score of 4.0 (p=0.001) or 6.0 (p<0.0001) in North Africans patients. PERSPECTIVES AND CONCLUSIONS: The incidence rates found in these studies were comparable to those reported in several European populations. This undoubtedly places France in the category of regions with a high risk zone of MS. The incidence of MS in women increased; thus, exogenous (or epigenetic) factors vary over time and may affect men and women differently. The course of MS appears more aggressive in North Africans than in Europeans patients.     

Epidemiology of multiple sclerosis in northern Greece

A total of 638 new cases of multiple sclerosis (MS) (365 females, 273 males) were found from 1970-1984 in northern Greece (Macedonia and Thrace); the average annual incidence rate was 1.79 per 100,000 inhabitants with increasing incidence from 1980-1984. A total of 729 people living in northern Greece suffered from MS on December 31, 1984 (prevalence rate 29.5 per 100,000 inhabitants). No difference was found between urban and rural areas. No difference from the international standards was found for sex incidence. The study confirms the quite high prevalence of MS despite the fact that northern Greece is in the intermediate risk zone.     

Multiple sclerosis in North Norway, and first appearance in an indigenous population

This study was performed to determine the prevalence of multiple sclerosis (MS) in 1993 and annual incidence rates 1983-1992, and to examine whether the disease occurs among the Sami people. According to earlier reports the two northernmost counties of Norway, Troms and Finnmark with 225,000 inhabitants, have a relatively low prevalence of MS: 20.6 per 100,000 in 1973 and 31.5 in 1983. Also no person who is of pure Sami heritage (i.e., with both parents speaking Sami natively) has been found with the disease. Except for the introduction of magnetic resonance imaging as a diagnostic tool, there has been no significant change in the neurological service in the area during the past 20 years. Files of patients with the diagnosis of MS were reviewed, and questionnaires were sent to all patients alive on the prevalence day of 1 January 1993. The prevalence in 1993 was 73.0 per 100,000. The mean crude annual incidence rate was 3.5 per 100,000 during the period 1983-1992 compared with 3.0 during 1974-1982. In 1983 there were no pure Sami among the MS patients, but one had a Sami father. On 1 January 1993 there were three patients with both Sami parents and three with only one Sami parent, which is a rate that is still lower than would be expected if the prevalence of MS among the Sami were similar to that in the rest of the Norwegian population. The study shows that the incidence of MS in Troms and Finnmark has been increasing over the past 10 years, but is still lower than on the western coast and in the eastern part of Norway. The lowest incidence is found in Finnmark, where the Sami population is highest. During the past 10 years MS has also been diagnosed among the Sami population.     

Prevalence and incidence of multiple sclerosis in Las Palmas, Canary Islands, Spain

OBJECTIVES: To determine the prevalence and incidence of multiple sclerosis (MS) in the city of Las Palmas (Canary Islands, Spain), geographically belonging to north-western Africa, but with European ancestry. METHODS: This population-based survey was conducted for a period of 5 years (1998-2002) in a Sanitary District of Las Palmas city (28 degrees 20' N), with a population of 82,623 inhabitants. Multiple sources were periodically investigated for case ascertainment. Patients with definite and probable MS were included. RESULTS: Sixty-four patients with MS were identified on prevalence day, December 31, 2002. According to Poser's criteria the crude prevalence rate was 77.5 per 100,000 (95% CI: 59.7-98.9). This rate decreased to 73.8 (95% CI: 56.5-94.8) according to McDonald's criteria. Age-adjusted rates for the world and European standard populations were 61.6 (95% CI: 47.1-78.9) and 70.6 (95% CI: 55-89), respectively. Prevalence was higher for women aged 25-44 years. In 17 patients onset of MS occurred within the study period. Average annual incidence was 4.1 per 100,000 (95% CI: 2.4-6.6). CONCLUSIONS: The prevalence and incidence rates in Las Palmas city are close to those reported from Continental Spain and other countries of southern Europe with similar social and ethnic background. These results highlight the role of racial-ethnic factors in the genesis of MS.     

A possible spatial and temporal cluster of multiple sclerosis in the town of Linguaglossa,Sicily

We carried out an epidemiological survey to determine prevalence and incidence of multiple sclerosis in the little town of Linguaglossa in the Province of Catania. We calculated prevalence rate as point prevalence at 1 January 2001 and incidence during 1991–2000.We studied the frequency of multiple sclerosis in the community of Linguaglossa in a population of 5,422 inhabitants in the 2001 census. The primary sources for the case ascertainment were the general practitioners of Linguaglossa, the local Italian Multiple Sclerosis Association and the neurological departments, Multiple Sclerosis Centers and private neurologists of the province of Catania. We considered as prevalent and incident cases all patients who satisfied the Poser’s diagnostic criteria. We detected 11 patients with multiple sclerosis who had had the onset of disease on prevalent day (P.D.). The onset–adjusted prevalence rate was 203/100,000 (95% CI 107–352).Prevalence was higher in women (247/100,000) than in men (154/100,000). From 1991 to 2000, 10 subjects with MS had clinical onset of disease. The mean annual incidence risk was 18.2/100,000 (C. I. 95 % 5.9–42.5).Conversely in the same population prevalence on 1 January 1991 was 37/100,000 while the onset adjusted annual incidence risk during the previous decade (1981–1991) was 3.6/100,000. Prevalence and incidence rates of MS during the last decade in the little town of Linguaglossa are higher than those found in the same area during the previous ten years and also than those reported in other Sicilian and Italian surveys suggesting a possible cluster of MS.     

High prevalence and fast rising incidence of multiple sclerosis in Caltanissetta, Sicily, southern Italy

BACKGROUND: Epidemiological studies conducted in Sicily and Sardinia, the two major Mediterranean islands, showed elevated incidence and prevalence of multiple sclerosis (MS)and a recent increase in disease frequency. OBJECTIVE: To confirm the central highlands of Sicily as areas of increasing MS prevalence and elevated incidence, we performed a follow-up study based on the town of Caltanissetta (Sicily), southern Italy. METHODS: We made a formal diagnostic reappraisal of all living patients found in the previous study performed in 1981. All possible information sources were used to search for patients affected by MS diagnosed according to the Poser criteria. We calculated prevalence ratios, for patients affected by MS who were living and resident in the study area on December 31, 2002. Crude and age- and sex-specific incidence ratios were computed for the period from January 1, 1993, to December 31, 2002. RESULTS: The prevalence of definite MS rose in 20 years from 69.2 (retrospective prevalence rate) to 165.8/100,000 population. We calculated the incidence of definite MS for the period 1970-2000. These rates calculated for 5-year periods increased from 2.3 to 9.2/100,000/year. CONCLUSION: This survey shows the highest prevalence and incidence figures of MS in the Mediterranean area and confirms central Sicily as a very-high-risk area for MS.     

Prevalence and incidence of multiple sclerosis in Catania, Sicily

OBJECTIVE: An epidemiologic survey was conducted to determine the prevalence and incidence of MS in the city of Catania, Sicily, Italy. Prevalence rate was calculated as point prevalence at January 1,1995, and incidence during 1974 to 1995. METHODS: The authors studied the frequency of MS in the community of Catania in a population of 333,075 inhabitants according to the 1991 census. The primary sources for the case ascertainment were the neurologic and motor rehabilitation departments, the MS Center, the Italian MS Association, private neurologists, and family doctors. All patients who satisfied the Poser criteria for clinically definite MS, laboratory-supported definite MS, clinically probable MS, and laboratory-supported probable MS were considered prevalent and incident cases. RESULTS: One hundred ninety-five patients with MS who had had the onset of disease on prevalence day in a population of 333,075 inhabitants were detected. The prevalence rate was 58.5 per 100,000 (95% CI 50.7 to 67.5). Prevalence was higher in women (62.0/100,000) than in men (54.8/100,000). The age-specific prevalence showed a peak in the group aged 35 to 44 (145.1/100,000). From 1975 to 1994, 170 subjects with MS had the clinical onset of the disease. The mean annual incidence was 2.3 per 100,000 (95% CI 2.0 to 2.6). Age-specific incidence showed a peak in the group aged 25 to 34 (6.32/100,000). Incidence for 5-year intervals increased from 1.3 during 1975 to 1979 to 3.9 during 1990 to 1994. CONCLUSIONS: These prevalence and incidence rates are close to those reported in other similar surveys carried out in Italy and southern Europe.     

Prevalence of multiple sclerosis in Bogotá, Colombia

Among Latin American countries, Colombia is considered a low-risk area for multiple sclerosis (MS) and no studies on MS prevalence have been conducted in any of the country's large urban settings. To fill this gap and assess the prevalence of MS in Bogotá as of December 31, 2002, this study reviewed the clinical records of patients diagnosed with MS in most Bogotá hospitals. This review produced a sample of 296 patients with an MS diagnosis whose reliability was verified by a neurologist with expertise in MS. The total prevalence rate identified for December 2002 was 4.41/100,000 inhabitants (95% CI 3.9-4.9), including a rate of 5.98/100,000 (95% CI 5.2-6.8) for women and 2.71/100,000 (95% CI 2.2-3.3) for men (differences measured at p < 0.001). The prevalence estimates for Bogotá, confirm the city's status as a low-risk area for MS.     

Multiple sclerosis in the Bern canton (Switzerland). An epidemiologic study

We conducted a study on the prevalence of multiple sclerosis in the canton of Berne (Switzerland) at the Department of Neurology (inpatient and outpatient sections) of the Inselspital hospital (University of Berne) in Berne. The canton of Berne is a heterogeneous region, geographically speaking, extending from the foot of the Jura mountains to high Alpine regions. There are approximately 920,000 inhabitants in an area of 6,000 square kilometers. Sources of our study were, besides the Department of Neurology of the University and the practising neurologists of Berne, the Association of Swiss Hospitals (VESKA) and the Swiss Multiple Sclerosis Society. For ensuring a safe diagnosis we employed a diagnosis score suggested by C. M. Poser et al (1983). This covered only safely established and probable cases of MS. To make sure of the actual residence of the retrospectively assessed patients we conducted a checkup with the relevant authorities. Besides personal data it was also possible, in a majority of patients, to obtain data on the onset and course of the disease. On 1, 1, 1986 1,016 MS patients were residents in the canton of Berne, according to our investigations. This corresponds to a prevalence rate of 110 MS patients for every 100.000 inhabitants. The sex ratio (female/male) is about 1.8: 1. The average age of the MS patients covered by the study was 50 years with an average duration of the disease of 18 years. From the data concerning the course of the disease our study was able to gain further pointers on the beginning of the disease, on the pattern of symptoms, course of the disease, and progression of multiple sclerosis.     

Prevalence and incidence of multiple sclerosis in the city of Monreale, Italy

The prevalence and incidence of multiple sclerosis (MS) in the city of Monreale, southern Italy were ascertained 10 years after a preliminary study in the same area. The study was undertaken in a population of 26,256 people. The patients were classified according to Poser’s criteria. The prevalence of MS on 31 December 1991 was 72.4 per 100,000 population. The incidence of MS for the period 1981–1991 was 3.3/100,000 per year. The mean period between onset and diagnosis of MS was 4.9 years for those patients found during this survey and 9.2 years for those in the first study. This study shows an increase of MS prevalence in Monreale city and a high incidence. The findings parallel the reduction of the lag time between onset and diagnosis. Received: 25 March 1997 Received in revised form: 30 June 1997 Accepted: 10 July 1997     

Prevalence and mortality of patients with multiple sclerosis in France in 2012: a study based on French health insurance data

Data on the prevalence of multiple sclerosis (MS) in France are scarce. National and regional updated estimates are needed to better plan health policies. In this nationwide study, we provided estimates of the prevalence of MS in France in 2012 and mortality rate in 2013. MS cases were identified in the French national health insurance database (SNIIRAM-PMSI) using reimbursement data for disease-modifying treatment, long-term disease status for MS, disability pension for MS, and hospitalisation for MS (MS ICD-10 code: G35). We identified 99,123 MS cases, corresponding to an overall crude prevalence rate of 151.2 per 100,000 inhabitants [95% confidence interval (CI) 150.3–152.2]: 210.0 per 100,000 in women (95% CI 208.4–211.5) and 88.7 per 100,000 in men (95% CI 87.6–89.7). The overall prevalence rate was 155.6 per 100,000 inhabitants (95% CI 154.7–156.6) after standardization on the 2013-European population. We observed a prevalence gradient with a higher prevalence (190–200 per 100,000) in North-Eastern France and a lower prevalence in Southern and Western France (126–140). The crude mortality rate in 2013 was 13.7 per 1,000 MS cases (11.4 in women and 20.3 in men). The standardized mortality ratio was 2.56 (95% CI 2.41–2.72). Our results revise upwards the estimation of MS prevalence in France and confirm the excess mortality of MS patients compared to the general population.     

The prevalence of multiple sclerosis in the north–west Italian province of Genoa

The objective of this study was to assess the prevalence of multiple sclerosis (MS), calculated as point prevalence on 31 December 1997, in the province of Genoa, North–western Italy. Methods The province of Genoa is located in North–western Italy, an area of 1835 km². On the point prevalence day the population consisted of 913,218 inhabitants. MS cases were identified by analysing archives of the hospitals with neurological or rehabilitation wards, neurologists serving the community, files of local chapters of the Italian MS society, all requests for oligoclonal bands analysis on CSF in the studied area. Patients included in the study were MS cases diagnosed before 31 December 1997 according to the Poser criteria resident in the province under study. Results A total of 857 subjects were alive and residing in the province of Genoa on the prevalence day. The overall crude prevalence rate was 94 per 100,000 (95% CI 88–100); 291 were males (34%) with a crude prevalence of 67 per 100,000 (95 % CI 60–76) and 566 were females (66%) with a prevalence of 118 per 100,000 (95% CI 108–128). The female/male ratio was 1.9. When age and sex were adjusted to the Italian standard population of 1991 prevalence was 85 per 100,000. Five hundred and thirty two out of the 857 patients agreed to be interviewed. The interviewed sample was representative of the prevalence sample: sex and gender distributions were identical in the two samples. The overall mean age was 48 (± 13) years (48 ± 12 years in males; 48 ± 14 years in females). Mean disease duration was 15 (± 10) years for males and 16 (± 11) years for females. Two hundred and ninety one (55 %) subjects had a relapsing remitting (RR) clinical course, 150 (28%) were secondary progressive (SP) and 91 (17%) were primary progressive (PP). Mean EDSS score was 5 (± 2; median 5). The mean age at time of onset was 33 (±10) years for males and 32 (± 11) years for females. The disease onset was monosymptomatic in 76% (n = 407) patients and polysymptomatic in 24% (n = 125). The mean length of time between clinical onset and diagnosis was 5 (± 6) years. Conclusion We confirmed that the province of Genoa is a very high risk area for MS. We found a high rate of patients with a PP course; also the proportion of patients with high disability scores is greater compared to previous studies.     

The prevalence and clinical characteristics of MS in northern Japan

In Japan, there is a low prevalence rate (PR) of multiple sclerosis (MS; 0.8-4.0/100,000) but a relatively high frequency of "optic-spinal form" MS (OS-MS). There have been no intensive epidemiologic frequency studies, however, in over 30 years. We performed a province-wide prevalence study of MS in the Tokachi province of Hokkaido, the northernmost island of Japan, and compared the observed clinical features with other populations in Japan and Western countries. Prevalence was determined on March 31, 2001. The primary sources for the case ascertainment were 13 hospitals that treated patients with neurologic diseases including MS in Tokachi. Patients were classified according to Poser's criteria. The prevalence rate of clinically definite or laboratory-supported definite MS (LSDMS) was 8.57 per 100,000 [31/361,726; male/female ratio=1:2.9, and age at onset=29.1+/-14.2 (mean+/-SD) years]. Out of the 31 patients, 5 (16%) were classified as OS-MS. The prevalence rate of MS in the Tokachi province was the highest reported in Orientals to date, although still low in comparison with Western communities at a similar latitude. In contrast to the previous reports in Japan, there was a relatively low frequency of OS-MS in Hokkaido.     

Occurrence of multiple sclerosis in central Finland: a regional and temporal comparison during 30 years

OBJECTIVE: We estimated the prevalence and incidence of multiple sclerosis (MS) in central Finland up to 2000. Rates were compared with those in other areas in Finland. MATERIAL AND METHOD: MS cases were identified in the hospital registry by ICD codes for demyelinating diseases from 1979 to 2000. Cases with definite MS were included. Incidence and prevalence were calculated with 95% CI and standardization was performed using direct method. RESULTS: In 1993 prevalence was 59/10(5) (n = 153). Incidence in 1979-93 was 3.8/10(5) person-years (n = 126). Rates are similar to average in areas with known rates of MS in Finland but substantially less than the over twofold MS risk in the neighbouring district Seinajoki. Extended follow-up to 2000 in central Finland showed increasing prevalence up to 105/10(5) (n = 277) and a significant increase in incidence 1994-98 up to 9.2/10(5) (n = 105). At the same time the diagnostic use of MRI increased up to 97%. CONCLUSION: Central Finland represents an average risk area of MS when compared with other areas of Finland but still a high risk in global comparison. The recent rapid increase in both prevalence and incidence is largely accounted for by increased use of MRI.     

MS and neuromyelitis optica in Martinique (French West Indies)

BACKGROUND AND OBJECTIVE: A population-based study is reported of MS in French Afro-Caribbeans (FAC) in Martinique. FAC are descendants of interracial mating that occurred between French Caucasians and black Africans in the 17th and the 18th centuries. METHODS: The authors surveyed the entire island of Martinique (area 1,128 km(2), population 357,000) between November 1997 and October 1999. RESULTS: Sixty-two patients (46 females, 16 males, ratio 2.9:1) were identified with definite or probable disease by the Poser criteria. Prevalence for all patients on December 31, 1998, was 17.4/10(5) (95% CI 13.1 to 21.7) and 14.3/10(5) (95% CI 10.4 to 18.2) for clinically definite cases (n = 51). Age range of patients on prevalence day was 17 to 73 years (mean +/- SD 39 +/- 11.3 years). Mean age at onset was 31.2 +/- 11 years. Overall, 9.7% had primary progressive disease and 19.4% had benign MS. A low proportion of definite and probable MS cases had oligoclonal bands in CSF (50.9%). Seventeen patients, 13 of whom were alive on prevalence day, had a relapsing form of neuromyelitis optica. CONCLUSION: The island of Martinique appears to have a low to medium prevalence of MS. MS was almost unknown in FAC in Martinique until the late 1970s. The apparent recent increase may be explained by improved recognition of patients, increased availability of MRI for diagnosis, increased disease awareness among physicians, increased survival of MS patients, or an actual increase in disease frequency.     

Increasing incidence of multiple sclerosis among women in Lorraine, Eastern France

This study aims to describe the prevalence and incidence rates of multiple sclerosis (MS) in Lorraine, France, and its secular trend from 1990 to 2002. Cases were sourced from the regional network of MS healthcare workers in the Lorraine region and include all cases with definite or probable MS according to Poser's criteria. We identified 2718 patients with MS on 31 December 2004. The prevalence rate was 120/100,000 (95% confidence interval [CI]: 119-121). Between 1990 and 2002, the average age- and sex-adjusted annual incidence rate was 5.5/100,000 (95% CI: 4.4-6.6). During this same period, there was a significant increase in overall incidence in women but not in men. The mean age at MS onset, disability score five years after onset, number of relapses during the first five years, and proportion of first attack with sequelae or polysymptomatic symptoms were not significantly different between each annual cohort during the study period. The prevalence and incidence rates of MS we found in our study were higher than in previous studies in France. The increase in incidence of MS between 1990 and 2002, mostly in women, was not related to better ascertainment of patients with mild disability.     

The prevalence of multiple sclerosis in the District of Santarém, Portugal

The prevalence of multiple sclerosis (MS) in Portugal is still unknown. Recent studies conducted in southern European countries showed higher than expected rates of MS prevalence.In an attempt to evaluate the MS prevalence in Santarém--a district with 62621 inhabitants (1991 census) located in the centre of Portugal--we have conducted a population survey in this district for five years. The crude prevalence rate found was 46.3/100,000. This figure is not different from findings recently reported in studies conducted at similar latitudes in neighbour southern European countries. This was the first population survey conducted in Portugal, and it is the first accurate contribution to the knowledge of the MS prevalence in this country.     

Prevalence of multiple sclerosis in Barrhead County, Alberta, Canada.

A prevalence study of multiple sclerosis (MS) was carried out in the town of Barrhead and surrounding county of Barrhead, in Alberta, Canada. The prevalence rate for clinically probable/definite multiple sclerosis on January 1, 1990 was 196/100,000. The average annual incidence rates for patients living in the area at onset were 1.31/100,000 for 1950-59, 4.97/100,000 for 1960-69, 3.77/100,000 for 1970-79, and 4.22/100,000 for 1980-89. Fifty percent of the patients were relapsing-remitting. Sixty percent were still walking without assistance. The female-to-male ratio was 1:1. Mean current age, age at onset and duration of illness were 49, 27 and 22 years respectively. The majority of patients (40%) experienced multiple symptom onset. Fifty percent were of single ethnic origin (either British or German); the rest were predominantly North European combinations. Forty percent of patients reported another MS relative. MS had affected the work status of 60% of the patients, 15% of whom were confined to an extended care centre.