Low and stable prevalence of rheumatoid arthritis in northern France

ObjectivesFew data are available on the prevalence of rheumatoid arthritis (RA) in France. Results of the Épidémiologie des rhumatismes inflammatoires (EPIRHUM-2) study suggest a lower prevalence in northern France (0.13%) than nationwide (0.31%) or in southern France (0.66%). Here, our objective was to confirm the lower prevalence of RA in northern France than in the rest of the country or in Europe.MethodsWe used the universal health insurance database to identify patients with RA in northern France (Nord-Pas de Calais region) in 2005.ResultsSeven thousand one hundred and twenty-eight patients of the 3,617,224 individuals receiving health insurance under the plan for salaried workers in the Nord-Pas de Calais region (89.3% of the population in the region) were listed as receiving free care for RA, yielding a prevalence of 197.1/100,000 population (female-to-male ratio, 2.99:1; mean age, 60.8 years).DiscussionThe prevalence of RA in northern France (0.197% in 2005) is lower than in southern France and northern Europe; thus, the prevalence gradient in France is in the opposite direction to the decreasing north-to-south gradient previously described in Europe. Although environmental and genetic factors involved in the pathogenesis of RA may be involved, the main explanation to the low prevalence in northern France may be the young age of the population.