Functional gastrointestinal disorders and overlap syndrome in Korea

Functional gastrointestinal disorders (FGIDs) are common in clinical practice and in communities around the world, including Korea. In a recent point prevalence study on functional dyspepsia (FD) in Korea using the Rome III criteria, 13.4% of community respondents reported dyspepsia. Forty-seven percent of these FD cases were classified as postprandial distress syndrome, 26% as epigastric pain syndrome, and 27% as overlap syndrome. Upper and lower GI symptoms commonly overlap and FGIDs are related to psychological disorders. In our recent study of subjects recruited from a health-screening program, the point prevalence of FD, irritable bowel syndrome (IBS), and reflux esophagitis (RE) was 13.2%, 3.9%, and 8.2%, respectively. The odds ratio of having FD and IBS together was estimated to be 4.4 (95% CI: 1.21-15.71). We found a positive relationship between FD and IBS. Recently, several genetic studies have suggested that serotonin transporter (SERT) gene polymorphisms and the G-protein β3 (GNβ3) C825T gene polymorphism are associated with FD and IBS. However, we did not find an association between SERT and GNβ3 C825T genetic polymorphisms and overlap syndrome, including FD and IBS, in our previous study in a Korean population. We therefore undertook a validation study of the Rome III criteria for FGIDs by factor analysis of symptoms. The sensitivity and specificity of Rome III criteria in discriminating FGIDs from organic diseases of the upper GI tract was 60% and 53%, respectively, while the sensitivity and specificity of these criteria for the lower GI tract was 80% and 50%, respectively, partially supporting the use of the Rome III criteria in Korea.