title: Back pain and health status in patients with clinically diagnosed ankylosing spondylitis, psoriatic arthritis and other spondyloarthritis: a cross-sectional population-based study.
abstract: BACKGROUND
  In the broader spectrum of back pain, inflammatory back pain (IBP) is a symptom that may indicate axial spondyloarthritis (SpA). The objectives of this study were to determine the frequency of current IBP, as a hallmark sign of possible axial SpA, in patients with ankylosing spondylitis (AS), psoriatic arthritis (PsA) and other SpA and to compare self-reported health between the groups with current IBP.
  
  
  METHODS
  Five-thousand seven hundred seventy one patients identified in the regional healthcare register of the most southern county of Sweden, diagnosed at least once by a physician (based on ICD-codes) with any type of SpA in 2003-2007, were sent a postal survey in 2009. Patients with current IBP were identified, based on self-reported back pain ≥3 months in the preceding year and fulfilling the Berlin criteria for IBP. The frequencies of IBP in AS, PsA and other SpA (including the remaining subgroups of SpA) were determined, and the groups were compared with regard to patient reported outcome measures (PROMs).
  
  
  RESULTS
  The frequency and proportion of patients with current IBP in AS, PsA and other SpA were 319 (43 %), 409 (31 %) and 282 (39 %) respectively, within the responders to the survey (N = 2785). The proportion was statistically higher in AS, compared to PsA (p < 0.001), but not for AS compared to other SpA (p = 0.112). PsA and other SpA, with current IBP, had similar (BASFI, EQ-5D, patients global assessment, fatigue, spinal pain) or worse (BASDAI) PROMs, compared to AS with current IBP. PsA with current IBP received pharmacological, anti-rheumatic, treatment more frequently than AS with current IBP, while AS and other SpA received treatment to a similar degree.
  
  
  CONCLUSIONS
  The proportion of patients with current IBP was substantial in all three groups and health reports in the non-AS groups were similar or worse compared to the AS group supporting the severity of IBP in these non-AS SpA groups. These findings may indicate a room for improvement concerning detection of axial disease within different subtypes of non-AS SpA, and possibly also for treatment.
authors.affiliation: Department of Rheumatology and Inflammation Research, Institute of Medicine, Sahlgrenska Academy, University of Gothenburg, Guldhedsgatan 10A, 405 30, Gothenburg, Sweden. ulf.lindstrom@gu.se.
authors.forename: Ulf
authors.initials: U
authors.lastname: Lindström
authors.affiliation: Department of Clinical Sciences, Section of Rheumatology, Lund University, Lund, Sweden. ann.bremander@spenshult.se.|School of Business, Engineering and Science, Halmstad University, Halmstad, Sweden. ann.bremander@spenshult.se.|Spenshult Research and Development Center, Halmstad, Sweden. ann.bremander@spenshult.se.
authors.forename: Ann
authors.initials: A
authors.lastname: Bremander
authors.affiliation: Department of Clinical Sciences, Section of Rheumatology, Lund University, Lund, Sweden. emma.haglund@spenshult.se.|School of Business, Engineering and Science, Halmstad University, Halmstad, Sweden. emma.haglund@spenshult.se.|Spenshult Research and Development Center, Halmstad, Sweden. emma.haglund@spenshult.se.
authors.forename: Emma
authors.initials: E
authors.lastname: Haglund
authors.affiliation: Department of Clinical Sciences, Section of Rheumatology, Lund University, Lund, Sweden. stefan.bergman@spenshult.se.|Spenshult Research and Development Center, Halmstad, Sweden. stefan.bergman@spenshult.se.|Primary Health Care Unit, Department of Public Health and Community Medicine, Institute of Medicine, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden. stefan.bergman@spenshult.se.
authors.forename: Stefan
authors.initials: S
authors.lastname: Bergman
authors.affiliation: Department of Clinical Sciences, Section of Orthopedics, Lund University, Lund, Sweden. ingemar.petersson@med.lu.se.
authors.forename: Ingemar F
authors.initials: IF
authors.lastname: Petersson
authors.affiliation: Department of Rheumatology and Inflammation Research, Institute of Medicine, Sahlgrenska Academy, University of Gothenburg, Guldhedsgatan 10A, 405 30, Gothenburg, Sweden. lennart.jacobsson@gu.se.|Department of Clinical Sciences, Section of Rheumatology, Lund University, Lund, Sweden. lennart.jacobsson@gu.se.
authors.forename: Lennart T H
authors.initials: LT
authors.lastname: Jacobsson
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D015535:Arthritis, Psoriatic / Q000175:diagnosis / Q000453:epidemiology*; D001416:Back Pain / Q000175:diagnosis / Q000453:epidemiology*; D003430:Cross-Sectional Studies; D005260:Female; D006304:Health Status; D006801:Humans; D008297:Male; D008875:Middle Aged; D011159:Population Surveillance / Q000379:methods; D025241:Spondylarthritis / Q000175:diagnosis / Q000453:epidemiology; D013167:Spondylitis, Ankylosing / Q000175:diagnosis / Q000453:epidemiology*; D013548:Sweden / Q000453:epidemiology; D055815:Young Adult