Using both electronic and paper databases, demographic information regarding age, gender, body mass index, smoking history, dietary habits; medical history such as type of IBD, IBD symptoms, location and behavior, medication use (past and current), history of other autoimmune disorders; surgical history (IBD and non-IBD related); laboratory indices such as IBD serology, Thiopurinemethyltransferase (TPMT), and infliximab levels will be collected.