[Irritable colon among 30-60-year old subjects. A cohort study of 4581 Danes].

With the aim to assess prevalence, incidence, recovery and risk factors of irritable bowel syndrome a follow-up study of 4581 Danes was carried out. The cohort was obtained by a sex- and age-stratified random sample of Danes living in the Western part of Copenhagen County. Participants were interviewed about abdominal symptoms. According to various definitions, the prevalence of irritable bowel syndrome varied from 5 to 65% and the incidence varied from 1 to 36%. At the five year follow-up only 5% of subjects with irritable bowel syndrome were free of all symptoms. Psychic vulnerability, female sex, younger age and having problems were strongly associated to irritable bowel syndrome, while lifestyle factor were not important risk factors. Populations defined as suffering from irritable bowel syndrome according to various definitions had less than 50% of subjects in common. It is concluded that irritable bowel symptoms are frequent, fluctuating phenomena in the general population. Women, the young, the psychic vulnerable, and people having problems are at greater risk of having irritable bowel syndrome. Different studies applying different definitions of irritable bowel syndrome can not be considered to be comparable.