title: Undifferentiated spondyloarthritis: a longterm followup.
abstract: 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.
  
  
  CONCLUSIONS
  In a longterm followup of 111 Brazilian patients with uSpA, HLA-B27 and buttock pain were significant predictors of progression to a definite disease.
authors.affiliation: Disciplina de Reumatologia, Faculdade de Medicina, Universidade de São Paulo, São Paulo SP, Brasil CEP 01246-903. pdsampaiobarros@uol.com.br
authors.forename: Percival D
authors.initials: PD
authors.lastname: Sampaio-Barros
authors.forename: Adriana B
authors.initials: AB
authors.lastname: Bortoluzzo
authors.forename: Roseneide A
authors.initials: RA
authors.lastname: Conde
authors.forename: Lilian Tereza L
authors.initials: LT
authors.lastname: Costallat
authors.forename: Adil M
authors.initials: AM
authors.lastname: Samara
authors.forename: Manoel B
authors.initials: MB
authors.lastname: Bértolo
mesh_terms: D000328:Adult; D044466:Asian People / Q000208:ethnology / Q000235:genetics; D044383:Black People / Q000208:ethnology / Q000235:genetics; D001938:Brazil / Q000453:epidemiology; D015331:Cohort Studies; D018450:Disease Progression; D005260:Female; D005500:Follow-Up Studies; D020022:Genetic Predisposition to Disease; D015796:HLA-B27 Antigen / Q000235:genetics; D006801:Humans; D007564:Japan / Q000208:ethnology; D008297:Male; D011446:Prospective Studies; D012446:Sacroiliac Joint / Q000473:pathology*; D025241:Spondylarthritis / Q000208:ethnology / Q000235:genetics / Q000473:pathology*; D013167:Spondylitis, Ankylosing / Q000208:ethnology / Q000235:genetics / Q000473:pathology; D009626:Terminology as Topic; D044465:White People / Q000208:ethnology / Q000235:genetics
chemical_list: D015796:HLA-B27 Antigen