- No direct comparison of health care cost in patients with inflammatory bowel disease across the European continent exists. The aim of this study was to assess the costs of investigations and treatment for diagnostics and during the first year after diagnosis in Europe. The EpiCom cohort is a prospective population-based inception cohort of unselected inflammatory bowel disease patients from 31 Western and Eastern European centers. Patients were followed every third month from diagnosis, and clinical data regarding treatment and investigations were collected. Costs were calculated in euros (&OV0556;) using the Danish Health Costs Register. One thousand three hundred sixty-seven patients were followed, 710 with ulcerative colitis, 509 with Crohn's disease, and 148 with inflammatory bowel disease unclassified. Total expenditure for the cohort was &OV0556;5,408,174 (investigations: &OV0556;2,042,990 [38%], surgery: &OV0556;1,427,648 [26%], biologicals: &OV0556;781,089 [14%], and standard treatment: &OV0556;1,156,520 [22%)]). Mean crude expenditure per patient in Western Europe (Eastern Europe) with Crohn's disease: investigations &OV0556;1803 (&OV0556;2160) (P = 0.44), surgery &OV0556;11,489 (&OV0556;13,973) (P = 0.14), standard treatment &OV0556;1027 (&OV0556;824) (P = 0.51), and biologicals &OV0556;7376 (&OV0556;8307) (P = 0.31). Mean crude expenditure per patient in Western Europe (Eastern Europe) with ulcerative colitis: investigations &OV0556;1189 (&OV0556;1518) (P < 0.01), surgery &OV0556;18,414 (&OV0556;12,395) (P = 0.18), standard treatment &OV0556;896 (&OV0556;798) (P < 0.05), and biologicals &OV0556;5681 (&OV0556;72) (P = 0.51). In this population-based unselected cohort, costs during the first year of disease were mainly incurred by investigative procedures and surgeries. However, biologicals accounted for >15% of costs. Long-term follow-up of the cohort is needed to assess the cost-effectiveness of biological agents.