O4-17. Ankylosing spondylitis and axial spondyloarthritis in patients with long-term inflammatory bowel disease
Alvilde M. Ossum [1,2], Øyvind Palm , Aida K. Lunder [2,4], Milada Cvancarova [1,5], Hasan Banitalebi , Anne Negård , Ole Høie , Magne Henriksen , Bjørn A. Moum [1,2], Marte L. Høivik  and the IBSEN Study Group
Affiliates: Department of Gastroenterology, Oslo University Hospital, Oslo, Norway , Faculty of Medicine, University of Oslo, Oslo, Norway , Department of Rheumatology, Oslo University Hospital, Oslo, Norway , Department of Diagnostic Imaging, Akershus University Hospital, Oslo, Norway , Faculty of Public Health, Oslo and Akershus University College, Oslo, Norway , Sørlandet Hospital, Department of Internal Medicine, Arendal, Norway , Østfold Hospital Trust, Gastroenterology, Norway 
Patients with inflammatory bowel disease (IBD) often suffer from rheumatic manifestations, including inflammatory back disorders. The prevalence of these disorders late in the course of IBD is poorly investigated. The aim of this study was to estimate the prevalence of inflammatory back disorders in patients with IBD 20 years after diagnosis and to investigate possible associations with IBD severity, HLA-B27 and the NOD2 genotype.
A population-based cohort (the IBSEN study) was followed prospectively for 20 years. Information covering IBD activity and rheumatic diseases was collected at the regular follow-ups. HLA-B27 and NOD2 were analysed as present or absent.
At 20 years, 599 members of the original cohort were alive, of whom 470 (78.5 %) were investigated (314 ulcerative colitis and 156 Crohn’s disease patients). Twenty-one patients (4.5 %) had ankylosing spondylitis. Axial spondyloarthritis was diagnosed in 36 patients (7.7 %), and inflammatory back pain was diagnosed in 54 patients (11.5 %). Chronic back pain (back pain > 3 months) was present in 220 patients (46.8 %). HLA-B27 was associated with ankylosing spondylitis, axial spondyloarthritis and inflammatory back pain, whereas no significant association was found for NOD2. A more chronic IBD course was associated with axial spondyloarthritis.
Our data revealed a high prevalence of ankylosing spondylitis, axial spondyloarthritis and inflammatory back pain 20 years after the IBD diagnosis. HLA-B27 but not NOD-2 was a predisposing factor for the inflammatory back disorders in IBD patients. Axial spondyloarthritis was associated with a more chronic active IBD disease course.