title: Gender-attributable differences in outcome of ankylosing spondylitis: long-term results from the Outcome in Ankylosing Spondylitis International Study.
abstract: OBJECTIVE
  To investigate gender-attributable differences regarding clinical outcome [disease activity, physical function and quality of life (QoL)] and radiographic damage in patients with AS over time.
  
  
  METHODS
  Data from the Outcome in AS International Study were used. Disease activity was assessed by the BASDAI, ASDAS and CRP; physical function by BASFI; QoL by the Short Form-36, Ankylosing Spondylitis Quality of Life (ASQoL) score and European Quality Of Life scale; and radiographic damage by the modified Stoke AS Spine Score (mSASSS). Cross-sectional comparative analyses were done at baseline. Next, separate models were created to assess gender-attributable differences on each outcome measure over time using time-adjusted generalized estimating equations.
  
  
  RESULTS
  A total of 216 patients [154 (72.3%) males, mean age 43.6 years (s.d. 12.7), symptom duration 20.5 years (s.d. 11.8), mean follow-up duration 8.3 years (s.d. 4.1)] were included. At baseline, male compared with female patients had lower self-reported disease activity (BASDAI 3.2 vs 3.9, P = 0.03) but more radiographic damage (mSASSS 13.8 vs 6.5, P = 0.02). No significant gender-attributable differences in other clinical parameters were found. In multivariable analysis, male gender was significantly associated with a better ASQoL (B = -1.18, 95% CI: -2.17, -0.20, P = 0.02), and in a separate model with a higher mSASSS over time (B = 8.24, 95% CI: 4.38, 12.09, P < 0.01).
  
  
  CONCLUSIONS
  In this prospective cohort study, no gender-attributable differences in disease activity or physical function over time were found. However, radiographic damage was more severe in males. Furthermore, males had a better QoL over time.
authors.affiliation: Department of Medicine, Division of Rheumatology, Maastricht University Medical Center, Maastricht.
authors.forename: Casper
authors.initials: C
authors.lastname: Webers
authors.affiliation: Department of Medicine, Division of Rheumatology, Maastricht University Medical Center, Maastricht, Care and Public Health Research Institute, Maastricht University, Maastricht.
authors.forename: Ivette
authors.initials: I
authors.lastname: Essers
authors.affiliation: Department of Rheumatology, Leiden University Medical Center, Leiden.
authors.forename: Sofia
authors.initials: S
authors.lastname: Ramiro
authors.affiliation: Department of Medicine, Division of Rheumatology, Maastricht University Medical Center, Maastricht, Care and Public Health Research Institute, Maastricht University, Maastricht.
authors.forename: Carmen
authors.initials: C
authors.lastname: Stolwijk
authors.affiliation: Department of Clinical Immunology & Rheumatology, Amsterdam Rheumatology Center, University of Amsterdam, Amsterdam, Department of Rheumatology, Atrium Medical Center, Heerlen, The Netherlands.
authors.forename: Robert
authors.initials: R
authors.lastname: Landewé
authors.affiliation: Department of Rheumatology, Leiden University Medical Center, Leiden.
authors.forename: Désirée
authors.initials: D
authors.lastname: van der Heijde
authors.affiliation: Department of Rheumatology, Ghent University Hospital and University of Ghent, Ghent, Belgium.
authors.forename: Filip
authors.initials: F
authors.lastname: van den Bosch
authors.affiliation: Department of Rheumatology, Paris Descartes University, Hôpital Cochin, Assistance Publique-Hôpitaux de Paris and INSERM (U1153); Epidemiologie Clinique et Biostatistiques, PRES Sorbonne Paris-Cité, Paris, France.
authors.forename: Maxime
authors.initials: M
authors.lastname: Dougados
authors.affiliation: Department of Medicine, Division of Rheumatology, Maastricht University Medical Center, Maastricht, Care and Public Health Research Institute, Maastricht University, Maastricht, a.van.tubergen@mumc.nl.
authors.forename: Astrid
authors.initials: A
authors.lastname: van Tubergen
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D000893:Anti-Inflammatory Agents / Q000627:therapeutic use; D003430:Cross-Sectional Studies; D004185:Disability Evaluation; D018450:Disease Progression; D005081:Exercise Therapy / Q000379:methods; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D038622:Internationality; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D010147:Pain Measurement; D011788:Quality of Life; D011859:Radiography; D018570:Risk Assessment; D012720:Severity of Illness Index; D012737:Sex Factors; D013167:Spondylitis, Ankylosing / Q000000981:diagnostic imaging* / Q000188:drug therapy / Q000503:physiopathology*; D013997:Time Factors; D016896:Treatment Outcome
chemical_list: D000893:Anti-Inflammatory Agents
keywords: ankylosing spondylitis; epidemiology; gender; longitudinal studies; sex