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

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.
petter.malmborg@sll.se

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.