Sex ratio of multiple sclerosis in Canada: a longitudinal study.
BACKGROUND: Incidence of multiple sclerosis is thought to be increasing, but this notion has been difficult to substantiate. In a longitudinal population-based dataset of patients with multiple sclerosis obtained over more than three decades, we did not show a difference in time to diagnosis by sex....
| Main Authors: | , , , , , , |
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| Format: | Journal article |
| Language: | English |
| Published: |
2006
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| _version_ | 1797060889789071360 |
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| author | Orton, S Herrera, B Yee, I Valdar, W Ramagopalan, S Sadovnick, A Ebers, G |
| author_facet | Orton, S Herrera, B Yee, I Valdar, W Ramagopalan, S Sadovnick, A Ebers, G |
| author_sort | Orton, S |
| collection | OXFORD |
| description | BACKGROUND: Incidence of multiple sclerosis is thought to be increasing, but this notion has been difficult to substantiate. In a longitudinal population-based dataset of patients with multiple sclerosis obtained over more than three decades, we did not show a difference in time to diagnosis by sex. We reasoned that if a sex-specific change in incidence was occurring, the female to male sex ratio would serve as a surrogate of incidence change. METHODS: Since environmental risk factors seem to act early in life, we calculated sex ratios by birth year in 27 074 Canadian patients with multiple sclerosis identified as part of a longitudinal population-based dataset. FINDINGS: The female to male sex ratio by year of birth has been increasing for at least 50 years and now exceeds 3.2:1 in Canada. Year of birth was a significant predictor for sex ratio (p<0.0001, chi(2)=124.4; rank correlation r=0.84). INTERPRETATION: The substantial increase in the female to male sex ratio in Canada seems to result from a disproportional increase in incidence of multiple sclerosis in women. This rapid change must have environmental origins even if it is associated with a gene-environment interaction, and implies that a large proportion of multiple sclerosis cases may be preventable in situ. Although the reasons why incidence of the disease is increasing are unknown, there are major implications for health-care provision because lifetime costs of multiple sclerosis exceed pound1 million per case in the UK. |
| first_indexed | 2024-03-06T20:23:20Z |
| format | Journal article |
| id | oxford-uuid:2e91c078-f828-4f01-98a5-a1fbd5f437f3 |
| institution | University of Oxford |
| language | English |
| last_indexed | 2024-03-06T20:23:20Z |
| publishDate | 2006 |
| record_format | dspace |
| spelling | oxford-uuid:2e91c078-f828-4f01-98a5-a1fbd5f437f32022-03-26T12:49:43ZSex ratio of multiple sclerosis in Canada: a longitudinal study.Journal articlehttp://purl.org/coar/resource_type/c_dcae04bcuuid:2e91c078-f828-4f01-98a5-a1fbd5f437f3EnglishSymplectic Elements at Oxford2006Orton, SHerrera, BYee, IValdar, WRamagopalan, SSadovnick, AEbers, GBACKGROUND: Incidence of multiple sclerosis is thought to be increasing, but this notion has been difficult to substantiate. In a longitudinal population-based dataset of patients with multiple sclerosis obtained over more than three decades, we did not show a difference in time to diagnosis by sex. We reasoned that if a sex-specific change in incidence was occurring, the female to male sex ratio would serve as a surrogate of incidence change. METHODS: Since environmental risk factors seem to act early in life, we calculated sex ratios by birth year in 27 074 Canadian patients with multiple sclerosis identified as part of a longitudinal population-based dataset. FINDINGS: The female to male sex ratio by year of birth has been increasing for at least 50 years and now exceeds 3.2:1 in Canada. Year of birth was a significant predictor for sex ratio (p<0.0001, chi(2)=124.4; rank correlation r=0.84). INTERPRETATION: The substantial increase in the female to male sex ratio in Canada seems to result from a disproportional increase in incidence of multiple sclerosis in women. This rapid change must have environmental origins even if it is associated with a gene-environment interaction, and implies that a large proportion of multiple sclerosis cases may be preventable in situ. Although the reasons why incidence of the disease is increasing are unknown, there are major implications for health-care provision because lifetime costs of multiple sclerosis exceed pound1 million per case in the UK. |
| spellingShingle | Orton, S Herrera, B Yee, I Valdar, W Ramagopalan, S Sadovnick, A Ebers, G Sex ratio of multiple sclerosis in Canada: a longitudinal study. |
| title | Sex ratio of multiple sclerosis in Canada: a longitudinal study. |
| title_full | Sex ratio of multiple sclerosis in Canada: a longitudinal study. |
| title_fullStr | Sex ratio of multiple sclerosis in Canada: a longitudinal study. |
| title_full_unstemmed | Sex ratio of multiple sclerosis in Canada: a longitudinal study. |
| title_short | Sex ratio of multiple sclerosis in Canada: a longitudinal study. |
| title_sort | sex ratio of multiple sclerosis in canada a longitudinal study |
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