According to a study in france The prevalence of IBS in the whole population surveyed was estimated to be 4.0%, with women more likely to be affected than men in the ratio 2.3:1. The annual incidence of the disease was estimated to be 3.6 cases per 1,000 of the population. Prevalence and incidence did not vary significantly across the age groups, educational levels, community size, or regions. Of the 445 IBS patients identified by the diagnostic questionnaire, 351 (79%) agreed to respond to the second questionnaire about the characteristics of symptoms and the medical management. Responders tended to be younger than non-responders.