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: 6.81). 02/2003; 74(1):25-8. DOI: 10.1136/jnnp.74.1.25
Source: PubMed


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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Available from: Pentti J Tienari, Feb 17, 2015
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    • "Their epidemiological features prior to data completion are shown here mainly for the purposes of assessing possible selection bias and impact of omissions. In general, reported incidences referred to all MS forms, with two surveys providing separate, crude or age- and sex-specific RRMS and PPMS data [54,59]. Surveys reporting incidence for intervals prior to 1985 covered long study periods dating back several decades, e.g., up to 1943 for the Faroes [19,21] and 1955 for Nuoro, Italy [27]. "
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    ABSTRACT: Background A debate surrounding multiple sclerosis epidemiology has centred on time-related incidence increases and the need of monitoring. The purpose of this study is to reassess multiple sclerosis incidence in the European Economic Area. Methods We conducted a systematic review of literature from 1965 onwards and integrated elements of original research, including requested or completed data by surveys authors and specific analyses. Results The review of 5323 documents yielded ten studies for age- and sex-specific analyses, and 21 studies for time-trend analysis of single data sets. After 1985, the incidence of multiple sclerosis ranged from 1.12 to 6.96 per 100,000 population, was higher in females, tripled with latitude, and doubled with study midpoint year. The north registered increasing trends from the 1960s and 1970s, with a historic drop in the Faroe Islands, and fairly stable data in the period 1980-2000; incidence rose in Italian and French populations in the period 1970-2000, in Evros (Greece) in the 1980s, and in the French West Indies in around 2000. Conclusions We conclude that the increase in multiple sclerosis incidence is only apparent, and that it is not specific to women. Monitoring of multiple sclerosis incidence might be appropriate for the European Economic Area.
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    • "Within Finland , the Southern Ostrobothnian region represents a high-risk area for MS, showing an exceptional familial clustering of MS cases. This particular study sample thus offers several advantages for genetic studies including high incidence of disease, high number of familial cases, and high proportion of progressivetype of MS (Sumelahti et al. 2000, 2003). Our genome-wide search and previous studies have identified four main candidate regions for MS: the HLA locus on 6p, the Myelin Basic Protein (MBP) locus on 18q, and two relatively wide regions on 5p12–p14 and 17q22–q24 (Tienari et al. 1992, 1998; Kuokkanen et al. 1997). "
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    Preview · Article · Aug 2004 · Genome Research
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    ABSTRACT: Diss. -- Helsingin yliopisto.
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