The prevalence of sacroiliitis in psoriatic arthritis: new perspectives from a large, multicenter cohort - A Department of Veterans Affairs Cooperative Study

Objective. To determine the prevalence of radiographic evidence of sacroili itis in a large population of patients with psoriatic arthritis. Patients and design. Patients were recruited from 15 clinical centers. This was part of a large, multicenter study of patients with an established dia gnosis of ankylosing spondylitis, psoriatic arthritis, or reactive arthriti s. For this cohort, an established diagnosis of psoriatic arthritis was req uired, with cutaneous manifestations and involvement of at least three appe ndicular joints. At entry, patients were not selected for the presence of a xial involvement. Radiographs - one anteroposterior view of the pelvis and one oblique view of each sacroiliac joint - were graded using the New York classification scale by a musculoskeletal radiologist masked to the specifi c diagnosis and clinical symptoms. Re-evaluation of 10% of the films 3 year s later quantified intraobserver variability. Results. Two hundred and two patients with psoriatic arthritis were studied . Duration of the disease averaged 12 years; all patients had psoriasis and peripheral arthritis. The prevalence of radiographic evidence of sacroilii tis (grade 2 or higher) was 78%; 71% of these, had grade 3 disease. Conclusions. Previously reported prevalence of sacroiliitis in patients wit h psoriatic arthritis ranges from 30% to 50%. The prevalence of radiographi c evidence of sacroiliitis in this large multicenter cohort of patients wit h appendicular psoriatic arthritis was substantially higher.