epidemiology

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Multiple sclerosis exhibits a higher incidence in temperate zones and there is considerable local variation in prevalence (1):

  • prevalence rates vary around the UK. Based on the figure of 130,000 people with MS, it is estimated that the number of people with MS in each nation is:

    • England is around 105,450 or 190 per 100,000
    • Wales about 5,600 or 179 per 100,000
    • Northern Ireland about 4,830 or 258 per 100,000
    • Scotland about 15,750 or 290 per 100,000
  • prevalence in the north of Scotland is particularly high. A study of north east Scotland found the level per 100,000 people in 2009 to be 229 in Aberdeen, 295 in Shetland and 402 in Orkney

Adult travellers take their risk with them when they travel from a temperate to a non-temperate zone. However, if a child moves to a high risk area under the age of 16 then they adopt the risk of the new area. This seems to indicate an environmental factor in the development of MS.

MS also exhibits:

  • F>M incidence - two to three times as many women as men
  • constitutes the most frequent cause of non-traumatic disability in the young adult population (2)
  • onset is usually between 16 and 50 years with a peak between 20-40 years
  • 15% of sufferers of the disease have a blood relative with MS
  • the most common pattern of disease is relapsing and remitting multiple sclerosis (RRMS) where periods of stability (remission) are followed by episodes when there are exacerbations of symptoms (relapses)
    • about 85 out of 100 people with MS have RRMS at onset (3,4)
    • around two-thirds of people who start with RRMS may develop secondary progressive MS MS: this occurs when there is a gradual accumulation of disability unrelated to relapses, which become less frequent or stop completely (3,4)
    • about 10 to 15 out of 100 people with MS have primary progressive MS where symptoms gradually develop and worsen over time from the start, without ever experiencing relapses and remissions (3,4)
  • 5% of males and females with MS are aged between 40 and 74 years of age
  • MS estimated incidence of between 8 and 11 new cases diagnosed each year in England per 100,000 population (5)
  • on average 4,950 new cases of MS are diagnosed each year in England
  • smoking rates among males with MS are likely to be higher than those in the general population
  • (5)
  • males and females with MS are more likely to be ex-smokers than males and females in the general population (5)
  • strong latitude gradient for the prevalence of multiple sclerosis, with an increase in prevalence of 1.03 times per degree of latitude (6)
    • a north to south decrease in prevalence by latitude gradient has been recognised in North America and western Europe, and a reverse south to north increase in gradient has been reported in Australia

  • the absolute age-adjusted risk for developing MS depends on the proximity of any affected relatives:

    relationship
    age-adjusted lifetime risk of MS
    affected cousin
    1%
    one parent or child affected
    2%
    one sibling affected
    3%
    dizygotic twin affected
    7%
    one parent and one sibling affected
    13%
    two parents affected
    20%
    two parents and one sibling affected
    23%
    monozygotic twin affected
    30%

Reference:

Last edited 11/2020 and last reviewed 11/2020

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