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.