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. 2014 Oct;20(12):1578-83.
doi: 10.1177/1352458514530021. Epub 2014 May 19.

New data identify an increasing sex ratio of multiple sclerosis in Sweden

Helga Westerlind  1 , Inger Boström  2 , Leszek Stawiarz  3 , Anne-Marie Landtblom  4 , Catarina Almqvist  5 , Jan Hillert  3
Affiliations

New data identify an increasing sex ratio of multiple sclerosis in Sweden

Helga Westerlind et al. Mult Scler. 2014 Oct.

Abstract

Background: An increasing women-to-men ratio in later birth cohorts of patients with multiple sclerosis (MS) has been observed in several populations and has been hypothesised to be due to one or several environmental factors of importance for disease aetiology. However, in a study based on data from the Swedish MS registry (SMSreg) this ratio was recently reported to be rather stable during the 20(th) century.

Objective: The purpose of this study was to reinvestigate the women-to-men ratio in Sweden based on data from all available data sources, including deceased patients.

Method: We combined data from the SMSreg with data from national patient registers.

Results: In total we obtained information on 19,510 MS patients born 1931-1985, 13,321 women and 6189 men. The women-to-men ratio increased from 1.70 for patients born in the 1930s to 2.67 for patients born in the 1980s. When comparing the coverage of SMSreg to the full data set, a significantly higher proportion of women born 1931-1935 compared to men born in the same period were found in SMSreg, resulting in a sampling bias hiding the increasing sex ratio in the full material.

Conclusion: The women-to-men ratio in MS has increased in Sweden during the 20(th) century similarly to observations in other western countries.

Keywords: Multiple sclerosis; epidemiology; prevalence proportion; register study; sex ratio.

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Conflict of interest statement

Conflicts of interest: None declared.

Figures

Figure 1.
Figure 1.
Sex ratios of multiple sclerosis in Sweden, analysed by year of birth from 1931–1985; and figures from the previously published sex ratio in Sweden. Sex ratios from Canada and Norway are taken from the articles and are estimated from the figures in their respective publications.
See this image and copyright information in PMC

Comment in

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