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A STUDY OF INCIDENCE RATE AND SPATIAL DISTRIBUTION OF PEDIATRIC IBD IN CALGARY, ALBERTA
R Parab1, GG Kaplan1, TA Griffiths1, JD Butzner2, I Wrobel2, KP Rioux1
1Department of Medicine, Division of Gastroenterology and Department of Pediatrics; 2Division of Gastroenterology, Gastrointestinal Research Group, The University of Calgary, Calgary, Alberta
BACKGROUND AND AIMS: Geo-epidemiology refers to the study of spatial patterns of disease occurrence and aims to identify environmental factors that may be etiologically relevant. To date, this has only been studied in the context of adult inflammatory bowel disease (IBD). In this study, we determined the incidence rate of pediatric IBD in Calgary and the spatial distribution of its occurrence.
METHODS: We used the pediatric IBD database at Alberta Children’s Hospital in Calgary, representing approximately 400 incident cases of pediatric (age <= 16 years) IBD diagnosed between 1983 and 2007. Medical chart review was used to verify the diagnosis of Crohn’s disease (CD), ulcerative colitis (UC), or indeterminate colitis (IC) on the basis of typical endoscopic, histologic, and radiographic features. Each patient’s postal code defined their place of residence at the time of diagnosis of IBD. The Statistics Canada Postal Code Conversion File was used to translate raw postal code data into a point location representing each incident case. Each case was plotted on a digital map of the city of Calgary using ArcMap®. Census tract data (abstracted using PCensus) indicated the number of children aged 0-16 within a specific region of the city. Between 2001 and 2006 we calculated the average annual incidence rate of pediatric IBD with 95% confidence intervals (CI) based on a Poisson distribution. Socioeconomic and ethnicity data were available through PCensus for each census tract.
RESULTS: The incidence rate of pediatric IBD in Calgary between 2001 and 2006 was 5.6 cases per 100,000 (95% CI: 4.4-7.0 per 105) person-years. After normalization of census data to account for the number of at risk individuals within each census tract, there were no clear clusters of CD, UC, or IC within Calgary.
CONCLUSION: There is no clear clustering of pediatric IBD within defined geographic regions in the city of Calgary, Alberta. These data suggest that, rather than environmental influences, genetic factors may play a more important role in early onset IBD.