P2-17. High prevalence of coeliac disease in a population-based childhood-onset IBD cohort from northern Stockholm County?

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Petter Malmborg MD PhD [1, 3], Maja Ideström MD PhD [2,3], Cecilia Zetterström MD PhD [2,3], Natalia Mouratidou MD [2], Henrik Arnell MD PhD [2,4].
Affiliates: [1] Sachsska Children’s Hospital, Stockholm, Sweden. [2] Astrid Lindgren Children’s Hospital, Karolinska University Hospital, Stockholm, Sweden, [3] Department of Women’s and Children’s Health, Karolinska Institutet, Stockholm, Sweden, [4] Department of Clinical Science, Intervention and Technology, Karolinska Institutet, Stockholm, Sweden.

Background
Register studies have demonstrated an association of IBD with increased risk of coeliac disease (CD). Upper endoscopy is recommended in the work-up of children with IBD [2]. Here we report the cumulative incidence of CD by age in a population-based childhood-onset IBD cohort.

Methods
All 256 patients diagnosed 1993-2007 with childhood-onset IBD in northern Stockholm County were followed from birth until 2011. At end of study the median patient-age was 20.0 (4.5-32.1) years.
During the study 242 (95%) of the patients were examined with upper endoscopy and 204 (80%) of the patients were also re-endoscoped at least once.

Results
Twelve patients in the cohort were diagnosed with CD. The median age at CD-diagnosis in the cohort was 12.1 (1.7-16.7) years.
CD was diagnosed prior to IBD diagnosis in two patients, at diagnostic IBD work-up in ten patients and at re-endoscopy in one patient.
The cumulative incidence of CD in the cohort at 5 years of age was 0.4% (CI 0.0-2.5), at 15 years 4.5% (CI 2.4-8.0), and at 25 years 4.9% (CI 2.7-8.5).
The cumulative incidence of CD at thirteen years of age in the childhood-onset IBD cohort was not significantly different from the prevalence of CD in a cross-sectional study of twelve-year-old children in Sweden born 1995 (3.2% versus 2.9% (p=0.86)).

Conclusion
Our study demonstrates a high cumulative incidence of CD by age in a childhood-onset IBD cohort. However, the estimated prevalence of CD in our cohort was similar to that found in children in a national cross-sectional study. Hence, our study doesn’t lend any support to an association of childhood-onset IBD with increased risk of CD.
The association of childhood-onset IBD with increased risk of CD in register studies is probably heavily biased by the routine use of upper endoscopy in the work-up of children with IBD.