To describe the clinical characteristics of inflammatory bowel disease (IBD) at diagnosis in The Netherlands at the population level in the era of biologics.

All patients with newly diagnosed IBD (diagnosis made between January 1, 2006 and January 1, 2007) followed in 9 general hospitals in the southwest of the Netherlands were included in this population-based inception cohort study.

A total of 413 patients were enrolled, of which 201 Crohn’s disease (CD) (48.7%), 188 ulcerative colitis (UC) (45.5%), and 24 IBD unclassified (5.8%), with a median age of 38 years (range, 14–95). Seventy-eight patients with CD (38.8%) had ileocolonic disease and 73 patients (36.3%) had pure colonic disease. In 8 patients (4.0%), the upper gastrointestinal tract was involved. Nineteen patients with CD (9.5%) had perianal disease. Thirty-nine patients with CD (19.4%) had stricturing phenotype. Of the patients with UC and IBDU, 39 (18.4%) suffered from pancolitis and 61 (29%) from proctitis. Severe endoscopic lesions at diagnosis were seen in 119 patients (28.8%, 68 CD, 49 UC, and 2 IBDU), whereas 98 patients (23.7%) had severe histological disease activity. Thirteen patients (3.1%, 10 CD and 3 UC) had extraintestinal manifestations at diagnosis. Twenty-three patients (5.6%, 20 CD and 3 UC) had fistula at diagnosis.

In this cohort, 31% of the patients with CD had complicated disease at diagnosis, 39% had ileocolonic disease, 9.5% had perianal disease, and in 4% the upper gastrointestinal tract was involved. Most patients with UC suffered from left-sided colitis (51%). Severe endoscopic lesions were reported in 34% of the patients with CD and 26% of the patients with UC. Three percent of the patients with IBD had extraintestinal manifestations.