Regional variations of multiple sclerosis prevalence in French farmers
- Sandra Vukusic (sandra.vukusic{at}chu-lyon.fr)
Abstract
Background:Studies on multiple sclerosis prevalence have been carried out worldwide, showing a heterogeneous distribution between countries and even between the different regions of a same country.
Methods: We estimated the regional and national prevalence of multiple sclerosis in France on January 1st, 2003, based on the computerized database of the national farmer health insurance system (“Mutualité Sociale Agricole").
Findings: There were 2667 cases of multiple sclerosis registered on the prevalence date, out of 4.098.477 affiliates. After standardization on age, the estimates for the national prevalence of multiple sclerosis in French farmers were 65.0 per 100.000 inhabitants (95% confidence interval: 62.5-67.5), 41.9 per 100.000 in men (39.1-44.7) and 96.3 per 100.000 in women (92.0-100.6). The prevalence of multiple sclerosis was significantly higher in the north-eastern regions (around 100 per 100.000 inhabitants) compared to the south-western regions (around 50 per 100.000 inhabitants).
Interpretation: Our study is the first to evaluate the overall prevalence of multiple sclerosis in France and its 22 regions using the same methodology. Our results may be generalized to the whole French population, as there is no convincing evidence of an increased or decreased susceptibility to multiple sclerosis among farmers or persons living in the countryside. This places France among the countries of medium to high prevalence. Confirming the uneven distribution of multiple sclerosis that correlates with the latitude raises once more the question of the role of genetic and environmental factors in the susceptibility to multiple sclerosis.
