OBJECTIVE: The aim of this study is to evaluate the cumulative probability of recurrence and admission rates in an inflammatory bowel disease (IBD) inception cohort diagnosed in 2003-2004.

METHODS: Data on medications, phenotypes and surgery for 513 individuals with ulcerative colitis (UC, n=300) and Crohn's disease (CD, n=213) were obtained from medical records and linked to population-based health administrative database information. The admission rates and cumulative probability of recurrences were estimated, and the association with the baseline factors and medication was tested.

RESULTS: The cumulative risk of first recurrence after 1, 5 and 7 years was 40%, 63%, and 66% in CD patients and 51%, 75%, and 79% in UC patients, respectively. The cumulative risk of first surgical relapse was 6%, 18%, and 23% at 1, 5 and 7 years in CD respectively. One hundred and CD patients (66%) and 142 UC patients (47%) had at least one IBD-related hospitalisation. The hospitalisation rate decreased from 7.0 days/person-year in year one to 0.9 day at year 5 in CD, and from 4.7 days to 0.4 days for UC patients. Age above 40, current smoking, stricturing behaviour, and disease localisation (colonic, ileocolonic, and upper-GI) at diagnosis were predictors of recurrence in CD. In UC, age above 40 and former smoker status were predictors of recurrence and left-sided and extensive colitis were predictors of first-time hospitalisation.

CONCLUSION: In an era of improved treatment options, the recurrence rates, but not the surgery or hospitalisation rates, have decreased for CD but not for UC. The phenotypic characteristics at diagnosis predict the risk of recurrence and hospitalisation.