With the introduction and increasing use of anti-TNF therapy in IBD, a major shift of costs has been observed with medication costs replacing in-patient care, such as hospitalization and surgery, as the greatest source of healthcare expenditure.[1] Most previous cost studies in IBD, however, relied on a single measurement of costs and were performed before the introduction of anti-TNF therapy in IBD.[2;3;7–10] Furthermore, only a limited number of studies have aimed to identify factors predicting IBD-related costs.[1;4;10;11]. The gene discussed is TNF; the disease is inflammatory bowel disease.