PT - JOURNAL ARTICLE AU - Percival D. Sampaio-Barros AU - Adriana B. Bortoluzzo AU - Roseneide A. Conde AU - Lilian Tereza L. Costallat AU - Adil M. Samara AU - Manoel B. Bértolo TI - Undifferentiated Spondyloarthritis: A Longterm Followup AID - 10.3899/jrheum.090625 DP - 2010 May 01 TA - The Journal of Rheumatology PG - jrheum.090625 4099 - http://www.jrheum.org/content/early/2010/04/28/jrheum.090625.short 4100 - http://www.jrheum.org/content/early/2010/04/28/jrheum.090625.full AB - Objective To analyze the longterm followup of a series of Brazilian patients with undifferentiated spondyloarthritis (uSpA). Methods Prospective study analyzing a group of 111 patients with the diagnosis of uSpA, fulfilling the European Spondylarthropathy Study Group and the Amor criteria, who were followed for 5 to 10 years in a single university referral center. Patients had their outcome analyzed at 5, 7, and 10 years. Results There was a predominance of men (81.1%), white ethnicity (78.4%), and positive HLA-B27 (61.3%), with a mean age at onset of 27.2 years. Twenty-seven patients presented development to ankylosing spondylitis (AS; 24.3%) and 3 to psoriatic arthritis (PsA; 2.7%), while 25 patients (22.5%) went into remission during the followup. Univariate logistic regression analysis revealed that ethnicity, HLA-B27, buttock pain, inflammatory low back pain, ankle involvement, grade I sacroiliitis at the beginning of the study, and the use of sulfasalazine were statistically associated with progression to AS. Multivariate logistic regression analysis revealed that HLA-B27 (p = 0.035, OR 6.720, 95% CI 11.45–39.43) and buttock pain (p = 0.009, OR 6.211, 95% CI 1.591–24.25) were statistically associated with progression to AS. Conclusion In a longterm followup of 111 Brazilian patients with uSpA, HLA-B27 and buttock pain were significant predictors of progression to a definite disease.