Association between irritable bowel syndrome and restless legs syndrome in the general population

This study aimed to explore the association between restless legs syndrome and irritable bowel syndrome in an epidemiological cohort. We included 3365 adults, of whom 1602 were female (age 52.5±7.5years), who had participated in the Korean Genome and Epidemiology Study (2005-2006). The diagnosis of restless legs syndrome was based on the criteria proposed by the International Restless Legs Syndrome Study Group, and irritable bowel syndrome was defined according to the Rome II criteria. The prevalence of each condition was determined and their association was tested by logistic regression analysis. Age, sex, haemoglobin concentration, renal insufficiency, use of medications and depressive mood were all adjusted for. The prevalence of restless legs syndrome and irritable bowel syndrome was 4.5 and 11.1%, respectively. Irritable bowel syndrome was more prevalent in the group with restless legs syndrome (24.0 versus 10.5%, P<0.001). Subjects with restless legs syndrome were older (54.2±8.4 versus 52.4±7.4, P=0.006) and more depressive (26.7 versus 12.5%, P<0.001), and were predominantly female (57.3 versus 47.2%, P=0.015), had more frequent insomnia symptoms (44.0 versus 28.2%, P<0.001), had lower haemoglobin concentration (13.7±1.5 versus 14.1±1.6gdL^-1P=0.004) and higher highly sensitive C-reactive protein (1.8±5.1 versus 1.4±2.9mgdL^-1, P=0.08). The adjusted odds ratio of restless legs syndrome in relation to irritable bowel syndrome was 2.59 (1.74-3.85, P<0.001). Irritable bowel syndrome appeared to be associated with restless legs syndrome independently from other major risk factors for restless legs syndrome. Searching for the mechanisms underlying this association is indicated.