ANKYLOSING SPONDYLITIS (AS) IN A COHORT OF PATIENTS WITH UNDIFFERENTIATED SPONDYLOARTHROPATHIES (U-SPA)

Background: Nearly 30 to 50% of various cohorts of patients with U-SpA from various ethnic groups develop AS after 2 to 10 years of follow-up.Objectives: To describe the frequency of AS and other SpA in a cohort of Mexican patients with U-SpA followed-up from 3 to 5 years.Methods: 89 patients with U-SpA fulfilling the ESSG criteria between 1998 and 2000 were assembled in a cohort, which underwent standardized clinical and radiographic evaluations.Results: We assessed the clinical and radiographic status of 49 patients (median age 22 + 8.7 years; 32.6% had juvenile onset; 78% HLA-B27 positive). The median follow-up at the present evaluation was 3.5 + 5.2 years and the duration of disease 7.8 + 7.4. Overall, 19 patients (41%) developed AS (8 men, 11 women); eight of these patients had juvenile onset. In the group of AS, 12 patients (92.3%) had HLA-B27 and 9 (64.2%) in the group of U-SpA group. There were no significant differences in the clinical characteristics between the group with AS and the group with U-SpA at last evaluation. Yet, the combination of of symptoms, which demonstrated the highest risk for AS was lumbar pain, HLA-B27 positivity and juvenile onset (p=0.05, OR 4.07, CI 95%: 1.1 to 14.6).Conclusion: Nearly 40% of patients with U-SpA followed up for 3 to 5 years, fulfilled AS criteria. The combination of lumbar pain, HLA-B27, and juvenile onset confers the highest risk.Citation: , volume , supplement , year 2004, page Session: Spondylarthropathies including psoriatic arthritis