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Journal of Neurology

, Volume 260, Issue 6, pp 1481–1488 | Cite as

Sex ratio of multiple sclerosis in persons born from 1930 to 1979 and its relation to latitude in Norway

  • Margitta T. KampmanEmail author
  • Jan Harald Aarseth
  • Nina Grytten
  • Espen Benjaminsen
  • Elisabeth Gulowsen Celius
  • Ole Petter Dahl
  • Trygve Holmøy
  • Kristin Løken-Amsrud
  • Rune Midgard
  • Kjell-Morten Myhr
  • Geir Risberg
  • Anita Vatne
  • Øivind Torkildsen
Original Communication

Abstract

A remarkable increase in female to male ratio of multiple sclerosis (MS) is recognised in high incidence areas. Norway is a high-risk area for MS, spanning latitudes 58–71°N. We studied whether the sex ratio has changed over time and whether it differs by clinical phenotype or by latitude. Population-based epidemiological data and data from the Norwegian MS Registry on patients born from 1930 to 1979 were combined in this study. Place of birth was retrieved from the Norwegian Population Registry and information on clinical subtypes was obtained from the Norwegian MS Registry. The female to male ratio ranged from 1.7 to 2.7 (median 2.0) in 5,469 patients born in Norway, and increased slightly by 5-year blocks of year of birth (p = 0.043). The sex ratio was 2.6:1 in 825 patients born 1970–1979, which is significantly higher than in those born 1930–1969 (p < 0.001). In patients with relapsing remitting onset, the sex ratio was 2.4:1, while it was 1.1:1 in those with primary progressive disease. The sex ratio did not differ between the south, the middle and the north of the country. The overall sex ratio of MS is strongly determined by cases with relapsing remitting onset. We did not observe the remarkable increase in sex ratios of MS reported from other high-risk areas. The high sex ratio in the youngest birth cohorts may change as an increasing proportion of cases in this age group is being diagnosed. Sex ratio was not associated with latitude.

Keywords

Multiple sclerosis Clinical phenotype Sex ratio Vitamin D Latitude Ultraviolet radiation 

Notes

Acknowledgments

The authors wish to thank Cathrine Smestad for data collection from the Oslo MS registry. This work was financially supported by the Neuromuscular Diseases Research Group at the University of Tromsø.

Conflicts of interest

The authors declare no conflict of interest.

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Copyright information

© Springer-Verlag Berlin Heidelberg 2013

Authors and Affiliations

  • Margitta T. Kampman
    • 1
    • 2
    Email author
  • Jan Harald Aarseth
    • 3
  • Nina Grytten
    • 3
    • 14
  • Espen Benjaminsen
    • 4
  • Elisabeth Gulowsen Celius
    • 5
  • Ole Petter Dahl
    • 6
  • Trygve Holmøy
    • 7
    • 8
  • Kristin Løken-Amsrud
    • 9
    • 10
  • Rune Midgard
    • 11
    • 12
  • Kjell-Morten Myhr
    • 3
    • 13
    • 14
  • Geir Risberg
    • 15
  • Anita Vatne
    • 16
  • Øivind Torkildsen
    • 3
    • 14
  1. 1.Centre for Clinical Research and EducationUniversity Hospital of North NorwayTromsøNorway
  2. 2.Department of Clinical MedicineUniversity of TromsøTromsoNorway
  3. 3.Department of Neurology, Norwegian Multiple Sclerosis Competence CentreHaukeland University HospitalBergenNorway
  4. 4.Department of NeurologyNordland HospitalBodøNorway
  5. 5.Department of NeurologyOslo University HospitalOsloNorway
  6. 6.Department of NeurologyNamsos HospitalNamsosNorway
  7. 7.Department of NeurologyAkershus University HospitalNordbyhagenNorway
  8. 8.Institute of Clinical MedicineUniversity of OsloOsloNorway
  9. 9.Department of NeurologyInnlandet Hospital TrustLillehammerNorway
  10. 10.Institute of Clinical MedicineUniversity of OsloOsloNorway
  11. 11.Department of NeurologyMolde HospitalMoldeNorway
  12. 12.Unit for Applied Clinical ResearchNorwegian University of Science and TechnologyTrondheimNorway
  13. 13.Department of Clinical MedicineUniversity of BergenBergenNorway
  14. 14.KG Jebsen Centre for MS-researchBergenNorway
  15. 15.Department of RehabilitationInnlandet Hospital TrustGjovikNorway
  16. 16.Department of NeurologySørlandet Hospital SSKKristiansandNorway

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