Epub: Boström et al. Sex ratio of multiple sclerosis in the National Swedish MS Register (SMSreg). Mult Scler. 2012 JunBackground:Sex ratio in multiple sclerosis has been reported from several geographical areas. The disease is more common in women. In Europe the female-to-male ratio varies from 1.1 to 3.4.
A recent study from Canada has reported a significant increase, with time, in female-to-male ratio in multiple sclerosis over the last 100 years.
Objective:The aim of this study was to analyse any change in sex ratio in multiple sclerosis in the Swedish population.
Methods:Data from the Swedish MS Register and data from the Swedish National Statistics Office were used to estimate sex ratio by year of birth and year of onset.
Results:In the analysis of sex ratio by year of birth there were 8834 patients (6271 women and 2563 men) born between 1931 and 1985. The mean women-to-men ratio was 2.62. No clear trend was noted for the women-to-men ratio by year of birth (Spearman's rho = 0.345, p = 0.298, n = 11). The number of patients analysed by year of onset was 9098 during the time period 1946 until 2005. The mean women-to-men ratio was 2.57. No significant change in women-to-men ratio (Spearman's rho = -0.007, p = 0.983, n = 12) with time was observed.
Conclusion:There is no evidence for an increasing women-to-men ratio with time amongst Swedish multiple sclerosis patients.
As we have posted previously about the Canadian study where the female to male ratio went from about 1. 9 in the 1930s to 3.0 in the 1970s of the study from Cretican study where the female ratio went from 0.9 in the 1980s to 2.1 in 2008. So in Sweden the sex ratio was about 2.6 and has not changed. So if we could understand what behaviours the Swedes have acquired at some time point before the 1930s that the Creticans took many more years to do, it would help us understand the risks of developing MS