Prevalence of ankylosing spondylitis and other spondyloarthropathies among patients with inflammatory bowel disease: a population study (the IBSEN study)

OBJECTIVE: To study the occurrence of spondyloarthropathies (SpA) in patients with inflammatory bowel disease (IBD) seen 6 years after IBD diagnosis. METHODS: In a population based cohort of 654 patients with IBD, 521 patients (80%) were investigated, which included a complete rheumatological examination. Radiographs of the sacroiliac joints and lumbar spine were performed in 406 of these patients (78%). The development of SpA was analyzed with regard to the presence of HLA-B27, duration of IBD symptoms, and the extent of intestinal inflammation. RESULTS: The occurrence of ankylosing spondylitis (AS) was 2.6% in ulcerative colitis and 6% in Crohn's disease (p = 0.08), yielding an overall prevalence of 3.7% in IBD. No correlation between localization or extent of the intestinal inflammation and presence of AS was found. HLA-B27 was present in 73% of cases with AS. The overall prevalence of SpA was 22%. Inflammatory back pain without AS (IBP) was found in 18% of the patients. Typical features of SpA were rare, while fibromyalgia was common in IBP, indicating that IBP is not a precursor or manifestation of SpA in patients with IBD. The prevalence of radiological sacroiliitis without clinical features of SpA was 2.0%. CONCLUSION: AS occurred frequently in patients with newly diagnosed IBD. IBP did not seem to predispose to AS or other forms of SpA. The overall prevalence of SpA was 22%, whereas the prevalence of asymptomatic radiological sacroiliitis was low.