Increasing prevalence of multiple sclerosis in Finland

Objectives – To follow‐up the prevalence trends of MS from 1983 to 1993 in western and southern Finland. MS epidemiology has been previously followed from 1964 to 1978 in these regions. The updated prevalences were correlated with incidence trends in the same period. Methods– Age‐adjusted and age‐specific MS prevalence rates were calculated for cases classified by Poser's criteria. Results– In the western health‐care districts, Seinäjoki and Vaasa, prevalences in 1993 were 202/10⁵ and 111/10⁵. In the southern district Uusimaa the respective figure was 108/10⁵. In Seinäjoki a significant 1.7‐fold increase was found in 1993 as compared to 1983, mainly due to increased incidence. In Uusimaa a significant 1.2‐fold increase in prevalence was found in the presence of stable incidence. In Vaasa prevalence was stable, although incidence was declining. Conclusion– The prevalence of MS is increasing in Seinäjoki and Uusimaa but not in Vaasa. Both the prevalence and incidence in Seinäjoki are now among the highest reported.     

Multiple sclerosis in western Finland: evidence for a founder effect

We have previously demonstrated that there is a high-risk focus for multiple sclerosis (MS) in the southern Ostrobothnian region of western Finland (population 376121 in 1993). Of the two southern Ostrobothnian health-care districts, Vaasa and Sein?joki, the incidence and prevalence of MS were especially high in the latter. In recent genetic studies, we identified haplotypes of the myelin basic protein (MBP) gene in a group of MS patients originating from southern Ostrobothnia, suggesting a founder effect. This finding led us to explore the population history of the southern Ostrobothnia and correlate it with MS epidemiology. Southern Ostrobothnia can be divided into three distinct regions with respect to its historical settlement: Vaasa, Sein?joki-south, and Sein?joki-north. Vaasa, the coastal region was settled by Swedes, who immigrated during the 13th century. In Vaasa, the prevalence of clinically definite MS (CDMS) in 1993 was 107/10(5) (95% CI 90-124). Sein?joki-south was populated from the 13th century onwards from southwestern Finland, a region which has been recognised as a high-risk focus of MS. In Sein?joki-south, the prevalence of CDMS in 1993 was 219/10(5) (95% CI 190-247). Sein?joki-north was inhabited rather late starting in the 16th century from eastern Finland. In Sein?joki-north the prevalence of CDMS in 1993 was 136/10(5) (95% CI 108-164). The historical settlement pattern of the southern Ostrobothnia indicates that its population is quite heterogeneous. Sein?joki-south has a very high prevalence of MS, significantly higher than its two neighbouring regions. The distinctive settlement history of Sein?joki-south, the historical link with the other southwestern high-risk foci and molecular genetic evidence, suggest that a founder effect plays an important role in the high-risk of MS in western Finland.     

The epidemiology of multiple sclerosis in Finland: increase of prevalence and stability of foci in high-risk areas

ABSTRACT- Reliable data on the epidemiology of multiple sclerosis (MS) in Finland are available from 1964 and 1972. They show that the whole country is a high-risk area of MS with clustering in the western part. A reassessment of the prevalence data was carried out in the southern province of Uusimaa and in the western province of Vaasa, the prevalence day being January 1, 1979. The age-adjusted prevalence was 52.9 per 100,000 in Uusimaa and 92.9 per 100,000 in Vaasa, figures that were three times higher than those recorded for the same areas in 1964. The communities with the highest prevalence rates in the province of Vaasa were the same as those in the survey of 1972; some rates exceeded 200 per 100,000. The increase in the prevalence rates may be due to a better registration of MS cases, but it may also represent a true increase, a possibility that only can be answered by further incidence studies.     

Multiple sclerosis in Finland: incidence trends and differences in relapsing remitting and primary progressive disease courses

Objective: To compare the secular trends and geographical differences in the incidence of relapsing-remitting (RRMS) and primary progressive multiple sclerosis (PPMS) in Finland, and to draw inferences about aetiological differences between the two forms of the disease. Methods: New multiple sclerosis cases in southern Uusimaa and the western districts Vaasa and Seinäjoki of Finland in 1979–1993 were verified from hospital records and classified into RRMS and PPMS. Patients met the Poser criteria for definite multiple sclerosis or otherwise satisfied the criteria for PPMS. Disease course was categorised by the same neurologist. Crude and age adjusted incidence in 1979–1993 was estimated. Results: During 1979–1993 the age adjusted incidence was 5.1 per 100 000 person-years in Uusimaa, 5.2 in Vaasa, and 11.6 in Seinäjoki. The rates in Uusimaa remained stable, while a decrease occurred in Vaasa and an increase in Seinäjoki. Between 1979–86 and 1987–93 the incidence of PPMS increased in Seinäjoki from 2.6 to 3.7 per 10⁵ and decreased in Vaasa from 1.9 to 0.2 per 10⁵; the trends were similar for RRMS. Conclusions: There are significant differences in secular trends for multiple sclerosis incidence in Finland by geographical area, but these are similar for PPMS and RRMS. The recent changes point to locally acting environmental factors. The parallel incidence trends for RRMS and PPMS suggest similar environmental triggers for the two clinical presentations of multiple sclerosis.     

The incidence of optic neuritis and its prognosis for multiple sclerosis

An incidence study of idiopathic optic neuritis (ON) was carried out in 2 geographic areas of Finland for the 9-year period 1970 to 1978. The southern province of Uusimaa composes a medium-risk and the western province of Vaasa a high-risk area for multiple sclerosis (MS). The risk for subsequent MS was determined. A total of 315 attacks on ON were recorded in 296 patients. The mean annual age-adjusted incidence for ON in Uusimaa was 2.2 and in Vaasa 2.5 per 100,000 population. The incidence figures remained unchanged all the time. The mean age at onset was 30 years. 19% of ON patients developed MS during the mean follow-up period of 5.1 years. When the life-table method of analysis was used, the probability of developing MS was 38% in Uusimaa and 24% in Vaasa 9 years after acute optic neuritis. In Uusimaa the risk of women for MS was significantly higher than in men. In 47%, the MS symptoms and signs developed within 1 year and in 90% within 5 years after the initial bout of ON. It is possible that only one part of idiopathic ON cases do have a relationship with MS.     

THE EPIDEMIOLOGY OF MULTIPLE SCLEROSIS AND TUBERCULOSIS IN FINLAND. A Study based on Mortality Statistics

Mortality statistics were used to check the previously observed uneven geographical distribution of multiple sclerosis (MS) in Finland, and also to compare the distribution of tuberculosis and MS with each other. In total, 331 MS deaths which could be regarded as deaths primarily due to MS were registered during the period from 1963 to 1971. The mean age at death was 49.9 years. The mean annual mortality rate was 0.8 per 100,000 population. The highest rates due to MS were registered in the western county of Vaasa. The cumulative mortality and birth rates showed a significant accumulation of MS cases to the western county of Vaasa and the southwestern county of Turku and Pori. A previous study revealed a high percentage of familial cases of first-degree kinship in the selected district of Jalasjarvi in the county of Vaasa. The mortality material revealed one additional MS case which raised the familial percentage to 13 among the living patients in this district. Statistics of tuberculosis have shown a constant accumulation of the disease in the western part of the country for more than 100 years. The mean annual mortality rate for tuberculosis was 17.1. The highest rate (23.0) was found in the western county of Vaasa, where the mortality rate (1.34) for MS was highest. Previous immigrant studies in Finland suggest that the uneven geographical distribution of tuberculosis is due to hereditary factors. The population of Finland consists of varying degrees of isolates, and the similarity of the distributions of MS and tuberculosis may thus reflect a common genetic factor in their aetiology.     

THE EPIDEMIOLOGY OF OPTIC NEURITIS IN FINLAND

Evidence has been presented that optic neuritis partially reflects benign cases of MS which are lost in the epidemiological investigation of the disease. As part of a large epidemiological investigation of MS, 221 patients with pure optic neuritis were identified during the period from January 1, 1967 to December 31, 1971. The mean annual incidence for the whole of Finland was 0.94 per 100,000 population. The female to male ratio was 1.7. The mean age at onset was 31.2 years. The distribution of optic neuritis by counties showed the highest mean annual incidence in the southwestern county of Turku and Pori (1.69) and in the western county of Vaasa (1.68). The prevalence data for MS were highest in these counties. A highly significant deviation from a random distribution according to place at onset and place of birth was obtained. Even the geographical distribution by smaller units, i.e. the combined clerical districts, revealed a firm accumulation to the western districts in the county of Vaasa and to the southwestern districts in the county of Turku and Pori. Thus, optic neuritis showed a similar geographical distribution to MS. The appearance of optic neuritis in the high-risk district of Jalasjarvi with several familial cases of MS did not increase the familial percentage when both conditions were considered as a single group. The risk of getting optic neuritis seems to depend on the influence of factors present during childhood. The epidemiological data point to a common factor in the aetiology of optic neuritis and MS.     

Epidemiologic trends in multiple sclerosis in M?re and Romsdal, Norway: a prevalence/incidence study in a stable population

The western part of Norway has been a low-to medium-frequency area for multiple sclerosis (MS). The prevalence of definite/probable MS on January 1, 1961, was 24.3/100,000 in the county of M?re and Romsdal, western Norway. Based on the same diagnostic criteria, the prevalence of definite/probable MS increased to 75.4/100,000 on January 1, 1985. The average annual incidence rate increased from 1.94/100,000 in the period 1950-1954 to 3.78/100,000 from 1975-1979. Remitting MS in the younger age groups of both sexes increased the most. We consider this increase of MS to be due to alteration in exogenous factors as variation in genetic susceptibility cannot account for the increase in the stable western Norwegian population. The rise in prevalence/incidence over the last 20 to 25 years in western Norway supports the theory that MS is a disease influenced by exogenous factors that show variation over time.     

An increase in the incidence of multiple sclerosis in Western Norway

Abstract– In the county of Hordaland, Western Norway, the prevalence of MS has been shown to have increased from 20/100,000 in 1963 to 60/100,000 in 1983. This study shows that the increase in prevalence was caused by a highly significant and marked increase in incidence over a 30-year period. The average annual incidence of about 2 per 100,000 population in 1953–1962 increased to 4 per 100,000 in the period 1968–1977. The rise in incidence was parallel for both sexes until 1970. In the last 10 years, the incidence has continued to increase among females, whereas a decrease has been observed among males.     

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.     

Survey of Guillain-Barré syndrome in southern Finland.

All acute Guillain-Barré syndrome (GBS) cases identified in the county of Uusimaa in southern Finland from 1981-1985 were analyzed. The incidence varied from 0.5 to 2.1 per 100,000 population. An antecedent event of possible etiologic significance was reported in 10% of the cases. Plasma exchange therapy was introduced during these years. Less children than expected fell ill, perhaps because of vaccinations, but a rise in the incidence of GBS in 1985 occurred during a nation-wide oral poliovirus vaccination campaign. A total of 19.4% of the patients needed respirator treatment, and plasma exchange therapy was given to 27.4% of these patients, among whom the time in respirator was shortened compared to equally affected individuals not given plasma exchange. The mortality was lower in the recent compared to the earlier period. This may be due to plasma exchange therapy.     

Multiple sclerosis in the Cambridge health district of east Anglia.

A survey of multiple sclerosis (MS) in the Cambridge Health District has identified 374 cases in a population of 288,410, giving a prevalence of 130 per 100,000. A total of 322 cases (86%) had either clinically definite or probable multiple sclerosis on 1 July 1990 (112 per 100,000) and 52 cases (14%) had suspected multiple sclerosis (18 per 100,000.) The incidence during 1989-91 was 5.94 per 100,000 per year. The prevalence figure is higher than in recent surveys from other southern parts of the United Kingdom, but correction for the age and sex characteristics of the at risk population eliminates these differences. The overall prevalence of multiple sclerosis is probably between 108 and 120 per 100,000 in the southern United Kingdom.     

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.     

Multiple sclerosis in southern Europe: Monreale City, Italy. A twenty-year follow-up incidence and prevalence study

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.     

The increasing incidence and prevalence of MS in a Sardinian province

OBJECTIVE: To verify incidence rates and their temporal trend in a homogeneous, ethnically, and genetically distinct population of central Sardinia (the Nuoro province). BACKGROUND: Intensive epidemiologic studies carried out in Sardinia since the 1970s have suggested that the prevalence and incidence of MS are much higher in this Mediterranean island compared with those found on mainland Italy. METHODS: The study area had a population of approximately 274, 000 people in the 1991 census. The authors adopted a complete enumerative approach by reviewing all possible sources of case collection available in the investigative area. RESULTS: Based on 469 MS patients, the mean annual incidence for 1955 to 1995 was 4.18 per 100,000 (or 4.3 per 100,000 if age- and sex-adjusted to the European population). The incidence, averaging 1.95 per 100,000 during 1955 to 1959, rose progressively over time, reaching rates of 6.6 in the quinquiennium 1985 to 1989 and 6.4 per 100,000 in 1990 to 1995. On December 31, 1994, the crude prevalence, based on 415 MS patients alive in the study area, was 151.9 per 100,000 (156.6 if adjusted to the European population). CONCLUSION: These incidence and prevalence rates are the highest to date that have been estimated for a large community in southern Europe, and they constitute some of the highest rates in the world. Based on other surveys, these results reinforce the position of Sardinia as a higher and rising prevalence area for MS compared with other Mediterranean populations. Genetic and social-historic data strengthen the hypothesis of the environmental role and genetic factors among Sardinians in determining the notable difference in MS frequency between Sardinians and other Mediterraneans.     

Epidemiological investigations into multiple sclerosis in Southern Hesse I.

An epidemiological field-survey on multiple sclerosis (MS) was carried out in the southern part of the state of Hesse (West Germany). Out of 472 patients primarily ascertained, 75% could finally be accepted as definite or probable MS cases. Cross-checking of the 3 sources for case-finding (practitioners and specialists, neurological hospital, MS society) revealed that case-finding in all and especially that of definite and probable MS cases was rather complete. The overall prevalence rate was 58.3, the annual incidence 2.15 and the mortality rate 2.0 per 100,000. Male patients showed a faster course than females. The prevalence in immigrants who mostly originated from Mediterranean countries, was significantly lower (14.3 per 100,000) than the prevalence in the German population (63.1 per 100,000).     

Incidence of multiple sclerosis among First Nations people in Alberta, Canada

Multiple sclerosis (MS) is thought to be rare among North American aboriginals, although few population-based frequency studies have been conducted. Data from government health databases were used to describe the incidence of MS among First Nations aboriginal people in the province of Alberta compared to the general population from 1994 to 2002. The general population rates were consistently higher than First Nations rates, but were essentially stable across this time span for both groups. For First Nations the MS incidence was 7.6 per 100,000 and 20.6 per 100,000 for the general population in 2002. During 2000-2002 for First Nations the incidence was 12.7 for females and 7.6 for males, with a female-to-male ratio of 1.7:1. During the same period the general population incidence was 32.2 for females and 12.7 for males, with a female-to-male ratio of 2.5:1. The peak incidence for both First Nations and the general population of Alberta was in the age group 30-39 years in 2002. The high incidence rates are consistent with high prevalence rates reported for both groups in 2002: 99.9 per 100,000 for First Nations and 335.0 per 100,000 for the general population. While the MS incidence in First Nations people is lower than in the general population of Alberta, it is not rare by worldwide standards.     

High incidence and increasing prevalence of MS in Enna (Sicily), southern Italy.

Twenty years after a first survey, a follow-up study was performed on the prevalence of MS in Enna (Sicily), southern Italy. The prevalence of definite MS rose from 53 to 120.2 per 100,000 population. The incidence of definite MS for the period 1986 to 1995 was 5.7 per 100,000 per year. The innermost part of Sicily shows an elevated prevalence of MS, second only to Sardinia in the Mediterranean area.     

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     

Suicide and attempted suicide in a general hospital in western Ethiopia

ABSTRACT Suicidal behaviour in western Ethiopia as seen in a general hospital is reported on. The suicide rate is at least 3–11 per 100,000 inhabitants per year (mean 4.5) which is higher than is usually reported from Africa. As many women as men seem to commit suicide and the incidence is highest in the age group 19–24 years and lowest in the oldest group. The incidence seems to be higher in urban areas. Hanging is the most frequent method used by both sexes.