Central sensitization and severity of gastrointestinal symptoms in irritable bowel syndrome, chronic pain syndromes, and inflammatory bowel disease

Background Central sensitization has been suggested as an explanation of the wide range of gastrointestinal and extraintestinal symptoms commonly seen in irritable bowel syndrome (IBS). In this study, the presence and level of central sensitization, and its association to gastrointestinal (GI) symptoms were explored in IBS in comparison with control groups. Methods We investigated patients with IBS (n = 215), chronic pain disorders (n = 36), and inflammatory bowel disease (IBD) (n = 40) and volunteers without chronic diseases (n = 112). The Central Sensitization Inventory (CSI) was translated and validated in Swedish and used together with the Highly Sensitive Person (HSP) scale to measure the presence and level of central sensitization. Furthermore, severity of GI symptoms (GSRS-IBS and IBS-SSS), and anxiety and depression (HAD) were determined. Key results The Swedish translation of CSI demonstrated excellent validity. Central sensitization, defined by validated cut-off levels for CSI and HSP, was common in the whole cohort (40% and 28%) and in IBS (57% and 35%). Study participants with central sensitization had more severe GI symptoms, anxiety and depression, than participants without central sensitization. Strong associations were seen between CSI and GI symptom severity in the whole cohort (GSRS-IBS: partial eta(2) = 0.455, p < 0.001; IBS-SSS: partial eta(2) = 0.408, p < 0.001), with decreasing strength in patients with chronic pain, IBD, IBS, and volunteers. Conclusion and Inferences Central sensitization was common in IBS and associated with GI symptom severity, but with stronger associations in chronic pain disorders and IBD. This implies that other mechanisms may be of equal or greater importance for GI symptom severity in IBS.