Change of diagnosis during the first five years after onset of inflammatory bowel disease: Results of a prospective follow-up study (the IBSEN Study)

Objective. An exact diagnosis of inflammatory bowel disease (IBD) and further subclassification may be difficult even after clinical, radiological and histological examinations. A correct subclassification is important for the success of both medical and surgical therapeutic strategies, but there is a dearth of information available on the frequency of changes in diagnosis in population-based studies. The objective of this work was prospectively to re-evaluate the diagnosis in an unselected cohort of IBD patients during the first five years after the initial diagnosis. Material and methods. Patients classified as IBD or possible IBD in the period 1990–94 (the IBSEN cohort) had their diagnosis re-evaluated after 1 and 5 years. Initially, the patients were classified as ulcerative colitis (UC), Crohn's disease (CD), indeterminate colitis (IC) or possible IBD. At the 5-year visit, patients were classified as UC, CD or non-IBD. Results. A total of 843 patients (518 UC, 221 CD, 40 IC and 64 possible IBD) were identified. Clinical information was available for 94% of the patients who survived after 5 years. A change in diagnosis was found in 9% of the patients initially classified as UC or CD. A change to non-IBD was more frequent than a change between UC and CD. A large proportion of patients initially classified as IC or possible IBD were diagnosed as non-IBD after 5 years (22.5% versus 50%). When IBD was confirmed in these groups, UC was more frequent than CD. Two changes in diagnosis during follow-up were observed in 2.8% of the patients; this was more frequent in patients initially classified as IC or possible IBD. Conclusions. There are obvious diagnostic problems in a minority of patients with IBD; a systematic follow-up is therefore important in these patients.