Article

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

School of Public Health, University of Tampere, PO Box 607, FIN-33101 Tampere, Finland.
Journal of Neurology Neurosurgery & Psychiatry (Impact Factor: 5.58). 02/2003; 74(1):25-8. DOI: 10.1136/jnnp.74.1.25
Source: PubMed

ABSTRACT 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.
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.
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 10(5) and decreased in Vaasa from 1.9 to 0.2 per 10(5); the trends were similar for RRMS.
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.

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    ABSTRACT: Background The risk of multiple sclerosis (MS) increases with increasing latitude. Taking into consideration that Norway has a large latitude range, a south-to-north gradient would be expected. However, previous studies have reported an uneven distribution of the disease in Norway, with a relatively low prevalence in the most northern parts of the country.We describe the incidence and prevalence of MS in a county in the north of Norway over a period of 40 years.Methods All patients with MS living in Nordland County in the period 1970¿2010 were identified by reviewing hospital charts. The patients were included if they met the criteria of definitive or probable MS according to Poser [Ann Neurol 13:227-231, 1983] or MS according to McDonalds [Ann Neurol 50:121-127, 2001]. Point prevalence at the beginning of the decades was calculated. The average annual incidence was calculated for 5-year periods.ResultsThe total crude prevalence on January 1, 2010 was 182.4 per 100 000. The annual incidence continuously increased from 0.7 per 100 000 in 1970 ¿ 1974 to 10.1 per 100,000 in 2005 ¿ 2009. The time delay from the first symptom to diagnosis was stable from 1975 to 2010. The proportion of primary progressive PPMS in the prevalence numbers was 38.2% in 1980, and decreases continuously, to 18.6% in 2010. The female to male prevalence ratio has been stable since 1990 at 2.2 to 1.Conclusion The prevalence and the incidence of MS have steadily increased over a 40 year period. Nordland County is a high-risk area for MS.
    BMC Neurology 12/2014; 14(1):226. DOI:10.1186/s12883-014-0226-8 · 2.49 Impact Factor
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    01/2010, Supervisor: Professor Mats Åström
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    01/2014; 2014:186950. DOI:10.1155/2014/186950

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