title: Disease Activity Score 28-ESR bears a similar relationship to treatment decisions across different rheumatologists, but misclassification is too frequent to replace physician judgement.
abstract: OBJECTIVE
  To determine whether physician factors are associated with disease activity status in RA, independently of 28-joint disease activity score (DAS28)-ESR and to re-evaluate DAS28-ESR misclassification rates for identifying active disease in usual practice.
  
  
  METHODS
  A prospective observational study of outpatients with RA seen by 17 rheumatologists across New Zealand. Active disease was defined by an increase in therapy together with a reason of 'active disease'; very low disease activity was defined by a decrease in therapy together with a reason of 'patient well'. The independent physician effect was assessed using logistic regression. Sensitivity and specificity of current DAS28-ESR thresholds were calculated.
  
  
  RESULTS
  In 511 patients, 178 had active disease, 220 had low disease activity, 37 had very low disease activity and 76 had uncertain disease activity status. There was no independent effect of physician upon active disease status (P = 0.16) with DAS28-ESR [(OR) 3.7] explaining around 50% of the variability in active disease status. There was a trend towards an independent effect of physician upon very low disease activity status (P = 0.06) and greater variability in the distribution of DAS28-ESR for patients in very low disease activity. DAS28-ESR thresholds showed a significant risk of misclassification for active disease.
  
  
  CONCLUSIONS
  DAS28-ESR discriminates satisfactorily between groups of patients with active and non-active disease, with no evidence of additional physician-specific factors to explain disease activity status. However, DAS28-ESR is not as good for discriminating remission from non-remission status. There are appreciable probabilities of misclassification error, which make DAS28-ESR inappropriate as a sole guide for treatment decisions.
authors.affiliation: Department of Medicine, University of Otago Wellington, PO Box 7343, Wellington 6242, New Zealand. will.taylor@otago.ac.nz
authors.forename: W J
authors.initials: WJ
authors.lastname: Taylor
authors.forename: A A
authors.initials: AA
authors.lastname: Harrison
authors.forename: J
authors.initials: J
authors.lastname: Highton
authors.forename: P
authors.initials: P
authors.lastname: Chapman
authors.forename: L
authors.initials: L
authors.lastname: Stamp
authors.forename: J
authors.initials: J
authors.lastname: Dockerty
authors.forename: F
authors.initials: F
authors.lastname: McQueen
authors.forename: P B B
authors.initials: PB
authors.lastname: Jones
authors.forename: D
authors.initials: D
authors.lastname: Ching
authors.forename: D
authors.initials: D
authors.lastname: Porter
authors.forename: C
authors.initials: C
authors.lastname: Rajapakse
authors.forename: S R
authors.initials: SR
authors.lastname: Rudge
authors.forename: G
authors.initials: G
authors.lastname: Taylor
authors.forename: S
authors.initials: S
authors.lastname: Kumar
authors.forename: T
authors.initials: T
authors.lastname: Macedo
authors.forename: M Sew
authors.initials: MS
authors.lastname: Hoy
mesh_terms: D000328:Adult; D000368:Aged; D018501:Antirheumatic Agents / Q000627:therapeutic use*; D001172:Arthritis, Rheumatoid / Q000175:diagnosis* / Q000188:drug therapy*; D003657:Decision Making; D005260:Female; D006801:Humans; D007600:Judgment; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D011594:Psychometrics; D012680:Sensitivity and Specificity; D012720:Severity of Illness Index
chemical_list: D018501:Antirheumatic Agents