Petter Malmborg 1, 2, Maja Ideström 1,2, Jan Björk 4,5, Annika Bergquist 4,6, Henrik Arnell 1,3, Björn Fischler 1,3, Eva Beijer 1,3, Antal Nemeth 1,3, Hans Hildebrand 1,2, Thomas Casswall 1, 3
1
Astrid Lindgren Children’s Hospital, Karolinska University Hospital. 2 Department of Women’s and Children’s Health, Karolinska Institutet. 3 Department of Clinical Science, Intervention and Technology, Karolinska Institutet. 4 Karolinska University Hospital. 5 Department of Medicine-Solna, Karolinska Institutet. 6 Department of Medicine -Huddinge, Karolinska Institutet.
petter.malmborg@sodersjukhuset.se

Background
Childhood-onset IBD (CO-IBD) is recognized as a distinct disease phenotype [1]. Some studies report that extra-intestinal manifestations occur more frequently in patients with CO-IBD [2]. Autoimmune liver disease (AILD) in patients with adult-onset IBD is associated with substantial intestinal and hepatic morbidity and mortality [3].

Methods
Medical records of all 280 patients diagnosed 1990-2007 with CO-IBD (<16 years) in northern Stockholm County were followed until 2011 (median follow-up time 8.8 years).
During the study period 22 patients were diagnosed with AILD (PSC (n=19), AIH (n=1), ASC (n=2)). The IBD-AILD patients were examined with ERCP or MRCP (n=21), liver biopsy (n=19) and auto-antibody tests (n=21). In the sub-cohort the median age at IBD diagnosis was 12.2 years and at AILD diagnosis 14.2 years. The IBD-AILD patients were followed for a median time of 6.9 years after AILD diagnosis.

Results
The prevalence of AILD in the CO-IBD cohort at was 5% at 5 years and 7% at 10 years after IBD diagnosis.
All IBD-AILD patients presented with an extensive colitis. Eleven of the patients were diagnosed with UC and 12 with CD. None of the IBD-AILD patients presented with or developed intestinal complications. One patient with IBD-AILD was colectomized.
The cumulative risk of complicated liver disease [4] in the IBD-AILD sub-cohort was 14% at 5 years after AILD diagnosis. No IBD-AILD patient underwent liver transplantation.
None of the IBD-AILD patients developed liver- or colorectal cancer and no patient in the sub-cohort died.

Conclusions
This is one of the first studies that provides an estimate of the risk of AILD in a population based CO-IBD cohort. The phenotype of CO-IBD patients with AILD seems to be characterized by extensive but uncomplicated colitis. CO-IBD patients with concomitant AILD seem to have a relatively low early intestinal- and hepatic morbidity and mortality.