title: Comparison of non-radiographic axial spondyloarthritis and ankylosing spondylitis patients--baseline characteristics, treatment adherence, and development of clinical variables during three years of anti-TNF therapy in clinical practice.
abstract: BACKGROUND
  The relationship between non-radiographic axial spondyloarthritis (nr-axSpA) and ankylosing spondylitis (AS) is currently debated. Using observational data from the South Swedish Arthritis Treatment Group register, we thus aimed to compare clinical development and treatment adherence between nr-axSpA and AS patients during three years of anti-TNF (tumor necrosis factor) therapy in clinical practice, and to explore the impact of inflammatory activity measured by CRP (C-reactive protein) at treatment initiation.
  
  
  METHODS
  Nr-axSpA and AS patients (n = 86/238) in southern Sweden, commencing anti-TNF therapy 1999-2011, were followed during three years. Anti-TNF cessation was defined as stopping therapy, without restarting another anti-TNF agent within three months. Differences in the three year developments of patient's visual analogue scale (VAS) scores for global health and pain, EuroQol 5-Dimensions utility, evaluator's global disease activity assessment, CRP, and ESR (erythrocyte sedimentation rate) were assessed by repeated ANOVA. Anti-TNF adherence was compared by Log rank test and Cox regression. In a subanalysis, the same outcomes were studied after splitting both groups into patients with/without baseline CRP elevation.
  
  
  RESULTS
  Nr-axSpA patients were more often female and had lower acute phase reactants at baseline. Apart from CRP, which remained lower in the nr-axSpA group throughout follow-up (p = 0.004), no between-group differences were detected regarding clinical developments (p >0.1 for all comparisons) or anti-TNF adherence (hazard ratio: 1.1 (95% CI 0.7 to 1.8) for the nr-axSpA vs. AS group) during three years. Elevated baseline CRP was similarly associated with superior clinical outcomes and treatment adherence in both groups.
  
  
  CONCLUSIONS
  With the exception of constantly lower CRP levels in the nr-axSpA group, three years anti-TNF therapy resulted in similar clinical outcomes and treatment adherence in nr-axSpA and AS patients, thus strengthening the hypothesis that these diagnoses represent different aspects/phases of the same disease.
authors.affiliation: Section of Rheumatology, Department of Clinical Sciences Lund, Lund University, Lund, Sweden. johan.81.karlsson@gmail.com.|Reumatologiska kliniken, Skånes Universitetssjukhus Lund, Kioskgatan 3, 22185, Lund, Sweden. johan.81.karlsson@gmail.com.
authors.forename: Johan K
authors.initials: JK
authors.lastname: Wallman
authors.affiliation: Section of Rheumatology, Department of Clinical Sciences Lund, Lund University, Lund, Sweden. meliha.c_kapetanovic@med.lu.se.
authors.forename: Meliha C
authors.initials: MC
authors.lastname: Kapetanovic
authors.affiliation: Section of Rheumatology, Department of Clinical Sciences Lund, Lund University, Lund, Sweden. ingemar.petersson@med.lu.se.|Section of Orthopedics, Department of Clinical Sciences Lund, Lund University, Lund, Sweden. ingemar.petersson@med.lu.se.
authors.forename: Ingemar F
authors.initials: IF
authors.lastname: Petersson
authors.affiliation: Section of Rheumatology, Department of Clinical Sciences Lund, Lund University, Lund, Sweden. pierre.geborek@med.lu.se.
authors.forename: Pierre
authors.initials: P
authors.lastname: Geborek
authors.affiliation: Section of Rheumatology, Department of Clinical Sciences Lund, Lund University, Lund, Sweden. larserik_kristensen@yahoo.com.|The Parker Institute, Department of Rheumatology, Copenhagen University Hospital, Frederiksberg and Bispebjerg, Denmark. larserik_kristensen@yahoo.com.
authors.forename: Lars Erik
authors.initials: LE
authors.lastname: Kristensen
mesh_terms: D000068879:Adalimumab / Q000627:therapeutic use; D000328:Adult; D000911:Antibodies, Monoclonal / Q000627:therapeutic use; D018501:Antirheumatic Agents / Q000627:therapeutic use*; D002097:C-Reactive Protein / Q000032:analysis / Q000378:metabolism; D000068582:Certolizumab Pegol / Q000627:therapeutic use; D000068800:Etanercept / Q000627:therapeutic use; D005260:Female; D006801:Humans; D000069285:Infliximab / Q000627:therapeutic use; D008297:Male; D010147:Pain Measurement; D012042:Registries; D025241:Spondylarthritis / Q000188:drug therapy* / Q000473:pathology*; D013167:Spondylitis, Ankylosing / Q000188:drug therapy* / Q000473:pathology*; D013548:Sweden; D014409:Tumor Necrosis Factor-alpha / Q000037:antagonists & inhibitors; D016903:Drug Monitoring
chemical_list: D000911:Antibodies, Monoclonal; D018501:Antirheumatic Agents; D014409:Tumor Necrosis Factor-alpha; D002097:C-Reactive Protein; C529000:golimumab; D000069285:Infliximab; D000068879:Adalimumab; D000068800:Etanercept; D000068582:Certolizumab Pegol