Natural history of functional gastrointestinal disorders: Comparison of two longitudinal population-based studies

Background: Functional gastrointestinal disorders are common but information on their natural history is limited. Aims: To document the natural history of functional gastrointestinal disorders in a population based study and to compare with the Olmsted County study. Method: A questionnaire was mailed to the same age- and gender-stratified random sample of the Icelandic population aged 18-75 in 1996 and 2006. Results were compared to the Olmsted County study. Results: Prevalence of functional gastrointestinal disorder symptoms was stable between these periods in time: 16.9% and 17.2% for irritable bowel syndrome, and 4.8% and 6.1% for functional dyspepsia. Onset of each disorder was more often higher in the Olmsted County study than in Iceland. Disappearance rates were similar for both studies. Transition probabilities varied across the different subgroups and were different between studies. The same proportion had the same symptoms in the initial and final studies. More subjects had no symptoms in Iceland (52% vs. 40%) and different symptoms at follow up (38% vs. 23%). Conclusion: Prevalence of functional gastrointestinal disorder symptoms was stable over time but the turnover in symptoms was high. A higher number of subjects had no symptoms in Iceland than in Olmsted County and there was a greater variation in subjects having different symptoms at follow up.