title: Seronegative spondyloarthritis.
abstract: Seronegative spondyloarthritis (SpA) is a group of inflammatory rheumatic diseases with common clinical and aetiological features, including axial and peripheral inflammatory arthritis, enthesitis, extra-articular manifestations and a close link to the presence of the human leucocyte antigen (HLA)-B27 epitope. Ankylosing spondylitis is the most common of the SpA diseases, with prevalence in the Caucasian population ranging between 0.15% and 1.8%, generally higher in populations with a higher background prevalence of HLA-B27 positivity. Incidence has been estimated between 0.49 (Japan) and 10 (Norway) per 100,000. The prevalence of psoriatic arthritis ranges from 0.02% to 0.2%, and the incidence in the normal population is 7.2 per 100,000 per year. In patients with existing psoriasis, the prevalence of psoriatic arthritis rises to 6-42%. The prevalence of reactive arthritis is dependent on the background incidence of gastrointestinal or genitourinary infections; incidence has been described as up to 30-40 per 100,000. SpA symptoms are present in up to 50% of patients with inflammatory bowel disease.
authors.affiliation: Menzies Research Institute, Hobart, Australia. Jane.Zochling@utas.edu.au
authors.forename: Jane
authors.initials: J
authors.lastname: Zochling
authors.forename: Emma U R
authors.initials: EU
authors.lastname: Smith
mesh_terms: D015535:Arthritis, Psoriatic / Q000453:epidemiology* / Q000276:immunology / Q000503:physiopathology; D005260:Female; D015796:HLA-B27 Antigen / Q000032:analysis; D006801:Humans; D015994:Incidence; D015212:Inflammatory Bowel Diseases / Q000453:epidemiology* / Q000276:immunology / Q000503:physiopathology; D008297:Male; D015995:Prevalence; D013167:Spondylitis, Ankylosing / Q000453:epidemiology* / Q000276:immunology / Q000503:physiopathology
chemical_list: D015796:HLA-B27 Antigen