National estimate of multiple sclerosis incidence in France (2001-2007)

Background: In France, the incidence of multiple sclerosis (MS) is not well known, and MS is one of the 30 long-term illnesses for which patients are covered for 100% of their health care costs. Objective: To estimate the incidence of MS in France and its geographic variations. Methods: We estimated the national rate for notification of MS to the main French health insurance system, and its confidence interval (CI), between November 2000 and October 2007, which covers 87% of the population. We analysed geographic variations using a Bayesian approach. Results: Between November 2000 and October 2007, among a covered population of 52,449,871, some 28,682 individuals were registered as having MS. After age standardization according to the European population, the notification rate for MS was 6.8 per 100,000 (6.7-6.9), 9.8 (9.7-10.0) in women and 3.7 (3.6-3.8) in men. When the under-notification rate (11.5% and 29%) was taken into account, the notification rate per 100,000 inhabitants was estimated between 7.6 and 8.8. The notification rate was higher in north-eastern France, and lower on the Atlantic coast and in the Alps as well as on both sides of the Rhone River. Conclusions: This study, conducted on a representative French population, provides for the first time national estimates of MS incidence between November 2000 and October 2007.