Comparing Health Administrative and Clinical Registry Data: Trends in Incidence and Prevalence of Pediatric Inflammatory Bowel Disease in British Columbia

PURPOSE: Canada maintains robust health administrative databases and British Columbia Children’s Hospital (BCCH), as the only tertiary care pediatric hospital in British Columbia (BC), maintains a comprehensive clinical inflammatory bowel disease (IBD) registry. To evaluate the strengths and weaknesses of utilizing health administrative and clinical registry data to study the epidemiology of IBD in BC, we conducted a population-based retrospective cohort study of all children <18 years of age who were diagnosed with IBD between 1996 and 2008 in BC. METHODS: IBD cases from health administrative data were identified using a combination of IBD-coded physician encounters and hospitalizations while a separate IBD cohort was identified from the BCCH clinical registry data. Age and gender standardized incidence and prevalence rates were fitted to Poisson regression models. RESULTS: The overall incidence of pediatric IBD identified in health administrative data increased from 7.1 (95% CI 5.5–9.2) in 1996 to 10.3 (95% CI 8.2–12.7) per 100,000 children in 2008. Similarly, the incidence of the BCCH cohort increased from 4.3 (95% CI 3.0–6.0) to 9.7 (95% CI 7.6–12.1) per 100,000. Children aged 10–17 had the highest rise in incidence in both data sources; however, the administrative data identified significantly more 10–17-year-olds and significantly less 6–9-year-olds (p<0.05) compared to clinical registry data. CONCLUSION: While the application of both health administrative and clinical registry data demonstrates that the incidence of IBD is increasing in BC, we identify strengths and limitations to both and suggest that the utilization of either data source requires unique considerations that mitigate misclassification biases.