Influence of phenotype at diagnosis and of other potential prognostic factors on the course of inflammatory bowel disease.

Objectives: Disease course in inflammatory bowel disease (IBD) is variable and difficult to predict. To optimize prognosis, it is of interest to identify phenotypic characteristics at disease onset and other prognostic factors that predict disease course. The aim of this study was to evaluate such factors in a population-based IBD group.

Methods: IBD patients diagnosed between 1 January 1991 and 1 January 2003 were included. A follow-up questionnaire was developed and medical records were reviewed. Patients were classified according to phenotype at diagnosis and risk factors were registered. Disease severity, cumulative medication use, and "surgical" and "nonsurgical" recurrence rates were calculated as outcome parameters.

Results: In total, 476 Crohn's disease (CD), 630 ulcerative colitis (UC), and 81 indeterminate colitis (IC) patients were diagnosed. In CD (mean follow-up 7.6 years), 50% had undergone resective surgery. In UC (mean follow-up 7 years), colectomy rate was 8.3%. First year cumulative recurrence rates per 100 patient-years for CD, UC, and IC were 53, 44, and 42%, respectively. In CD, small bowel localization and stricturing disease were negative prognostic factors for surgery, as was young age. Overall recurrence rate was increased by young age and current smoking. In UC, extensive colitis increased surgical risk. In UC, older age at diagnosis initially increased recurrence risk but was subsequently protective.

Conclusions: This population-based IBD study showed high recurrence rates in the first year. In CD, small bowel localization, stricturing disease, and young age were predictive for disease recurrence. In UC, extensive colitis and older age at diagnosis were negative prognostic predictors.