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P644 Epidemiology and characteristics of inflammatory bowel disease in a large population-based cohort in the Netherlands.

J. de Groof*1, N. Rossen2, B. van Rhijn2, E. Karregat2, K. Boonstra2, I. Hageman2, P. Kingma3, T. Naber3, J. van den Brande3, R. Mallant-Hent4, M. Mundt4, G. D'Haens2, C. Ponsioen2

1Academic Medical Center, Surgery, Amsterdam, Netherlands, 2Academic Medical Center, Gastroenterology & Hepatology, Amsterdam, Netherlands, 3Tergooi, Gastroenterology & Hepatology, Hilversum, Netherlands, 4Flevohospital, Gastroenterology & Hepatology, Almere, Netherlands

Background

Results from population based studies in inflammatory bowel disease (IBD) will reveal information on the disease phenotype and may facilitate adequate treatment stratification. Aim of this study was to update prevalence and incidence rates of IBD in a population-based cohort covering 319,976 inhabitants. In addition, use of medical therapy and surgical procedures for IBD were assessed.

Methods

IBD patients living in the adherence area receiving medical care at 3 regional (non-academic) hospitals in the Netherlands between 1-1-2004 and 1-1-2010 were identified. Three independent hospital databases were used for case-finding. Cochrane-Armitage trend test was used to test change in prevalence over time. Montreal classification was used to report on IBD behavior and location. Data on medical and surgical treatment were obtained from medical records.

Results

Case-finding identified 2,466 possible IBD patients. In total, 1,461 IBD patients were included (40.7% male). 761 (52.1%) patients had ulcerative colitis (UC), 579 (39.6%) Crohn's disease (CD) and 121 (8.3%) IBD-unspecified (IBD-U). Point prevalence of IBD was 432.1 (CI 409.7-454.5) per 100,000 inhabitants on 1-1-2010 (UC: 225.6, CD 171.8, IBD-U 34.7). Prevalence increased significantly over time from 1-1-2004 to 1-1-2010 ( Χ 2=49.4, p<0.0001). The mean annual incidence between 2004 and 2009 for IBD was 29.6 (CI 23.6-35.5) per 100,000 inhabitants per year (35.0 for UC, 20.2 for CD and 2.2 for IBD-U). Two peaks in the mean annual incidence rate were observed in UC patients in the age categories 40-49 and 70-79 years. In CD, an incidence peak was observed in young adolescent patients. Left-sided colitis was most commonly observed in UC patients (46.1%), whereas 23.7% had proctitis and 30.2% pancolitis. In the majority of CD patients ileocolonic involvement (L3)(36.3%) was observed. 30.4% had ileitis without colitis (L1), 32.2% had colitis (L2) and 1.1% had upper GI involvement. In CD patients, 53.9 % had nonstricturing, nonpenetrating behavior (B1). Stricturing, nonpenetrating behaviour (B2)was found in 21.4% of patients and penetrating in 24.7% (B3). A history of steroid use was significantly more common in CD as compared to UC patients (81.5% versus 62.9%, p<0.0001). Proctocolectomy was performed in 4.1% of UC patients after a median follow-up of 8.0 years (IQR 5.0-16.0). In CD patients an ileocecal resection was performed in 12.4%.

Conclusion

Point prevalence of IBD was 432.1 per 100,000 inhabitants and increased significantly over the study period. The mean incidence of IBD was 29.6 per 100,000 inhabitants per year. Whereas the incidence of CD was highest in lower age groups, two peaks in the incidence of UC were observed. Steroid use was significantly more common in CD patients.