The present invention provides a method of assessing whether an individual is at high risk or low risk of inflammatory bowel disease (IBD) progression by determining the expression level of two or more genes in a whole blood sample. Also provided are methods for treating IBD in an individual who is determined to be at high risk or low risk for IBD progression, and kits for assessing whether an individual is at high risk or low risk for IBD progression. Arrays, and methods of providing arrays, of patient-identified selected gene expression products from a whole blood sample of a patient are also provided.