title: The burden of non-radiographic axial spondyloarthritis.
abstract: OBJECTIVE
  To identify patients earlier, new classification criteria have been introduced for axial spondyloarthritis (axSpA). Patients who satisfy the clinical or imaging criteria for axSpA in the absence of definite sacroiliac joint changes on pelvic x-rays are classified as having non-radiographic axSpA. Although the burden associated with radiographic axSpA (i.e., ankylosing spondylitis) has been extensively studied, the impact of non-radiographic disease is not well understood. The purpose of this review is to provide an overview of the burden of illness in non-radiographic axSpA, including epidemiology and effects on patients׳ functioning and health-related quality of life (HR-QoL).
  
  
  METHODS
  A PubMed search was performed using relevant key words (e.g., "spondyloarthritis," "ankylosing spondylitis," "epidemiology," and "quality of life") to examine literature published from 2003 to 2013.
  
  
  RESULTS
  Studies conducted to date suggest that radiographic progression is detected in approximately 10% of patients with non-radiographic axSpA over 2 years. Differences between patients with non-radiographic and radiographic axSpA were found in age, symptom duration, and gender distribution. Although less inflammation (i.e., lower C-reactive protein levels and less spinal inflammation on MRI) and less impairment in spinal mobility are observed in non-radiographic than in radiographic axSpA, the 2 conditions pose a similar burden in terms of disease activity, physical function, HR-QoL impairment.
  
  
  CONCLUSIONS
  Patients with non-radiographic axSpA are more frequently female. Although patients with non-radiographic axSpA have shorter disease duration and lack radiological changes, they demonstrate a substantial burden of illness, with self-reported disease activity and functional impairments comparable to those found in patients with radiographic disease.
authors.affiliation: Division of Rheumatology, Department of Internal Medicine, Maastricht University Medical Center and CAPHRI Research Institute, P Debyelaan 25, 6229 HX, Maastricht, The Netherlands. Electronic address: a.boonen@mumc.nl.
authors.forename: Annelies
authors.initials: A
authors.lastname: Boonen
authors.affiliation: Charité-Universitätsmedizin Berlin, Berlin, Germany.
authors.forename: Joachim
authors.initials: J
authors.lastname: Sieper
authors.affiliation: Department of Rheumatology, Leiden University Medical Center, Leiden, The Netherlands.
authors.forename: Désirée
authors.initials: D
authors.lastname: van der Heijde
authors.affiliation: Department of Rheumatology, Paris Descartes University, Hôpital Cochin, Assistance Publique, Hôpitaux de Paris, INSERM (U1153): Clinical epidemiology and biostatistics, PRES Sorbonne Paris-Cité, Paris, France.
authors.forename: Maxime
authors.initials: M
authors.lastname: Dougados
authors.affiliation: Pfizer Inc., Collegeville, PA.
authors.forename: Jack F
authors.initials: JF
authors.lastname: Bukowski
authors.affiliation: Pfizer Inc., Collegeville, PA.
authors.forename: Satish
authors.initials: S
authors.lastname: Valluri
authors.affiliation: Pfizer Inc., Collegeville, PA.
authors.forename: Bonnie
authors.initials: B
authors.lastname: Vlahos
authors.affiliation: Pfizer Inc., Collegeville, PA.
authors.forename: Sameer
authors.initials: S
authors.lastname: Kotak
mesh_terms: D017281:Cost of Illness; D006801:Humans; D011788:Quality of Life; D011859:Radiography; D012446:Sacroiliac Joint / Q000000981:diagnostic imaging*; D012720:Severity of Illness Index; D025241:Spondylarthritis / Q000175:diagnosis* / Q000000981:diagnostic imaging
keywords: Ankylosing spondylitis; Burden of illness; Cost, work productivity; Disease activity; Epidemiology; Non-radiographic axial spondyloarthritis; Physical function; Quality of life