title: Validation of the 28-joint Disease Activity Score (DAS28) and European League Against Rheumatism response criteria based on C-reactive protein against disease progression in patients with rheumatoid arthritis, and comparison with the DAS28 based on erythrocyte sedimentation rate.
abstract: OBJECTIVE
  To validate and compare the definition of the Disease Activity Score 28 based on C-reactive protein (DAS28 (CRP)) to the definition based on erythrocyte sedimentation rate (ESR).
  
  
  METHODS
  Data were analysed from two randomised, double-blind, placebo-controlled trials of abatacept of 6-month and 12-month duration in patients with rheumatoid arthritis. European League Against Rheumatism (EULAR) response criteria and the proportion of patients in remission (DAS28 <2.6) based on the two DAS28 definitions were examined. Trends in radiographic progression (erosion score, joint space narrowing score and total score) and physical function (Health Assessment Questionnaire Disability Index (HAQ-DI)) across the EULAR responder states (none, moderate and good) were analysed.
  
  
  RESULTS
  There was general agreement in determining the EULAR responder state using both DAS28 definitions (kappa = 0.80, 95% CI 0.76 to 0.83). Overall, there was 82.4% agreement on the EULAR response criteria; when disagreements occurred, the DAS28 (CRP) yielded a better EULAR response more often then DAS28 (ESR) (12.6% vs 4.9%, respectively). There was also agreement in determining remission: kappa = 0.69 (95% CI 0.60 to 0.78). Radiographic progression decreased in patients treated with abatacept across EULAR states (from none to moderate to good) based on both definitions. For patients treated with placebo, the trend was not as pronounced, with radiographic scores higher for moderate vs non-responders. For physical function, similar trends were observed across the EULAR states for both DAS28 definitions.
  
  
  CONCLUSIONS
  The DAS28 (CRP) has been validated against radiographic progression and physical function. While the DAS28 (CRP) yielded a better EULAR response more often than the DAS28 (ESR), the validation profile was similar to the DAS28 (ESR), indicating that both measures are useful for assessing disease activity in patients with rheumatoid arthritis.
authors.affiliation: Department of Epidemiology and Community Medicine, University of Ottawa, Canada. gawells@ottawaheart.ca
authors.forename: G
authors.initials: G
authors.lastname: Wells
authors.forename: J-C
authors.initials: JC
authors.lastname: Becker
authors.forename: J
authors.initials: J
authors.lastname: Teng
authors.forename: M
authors.initials: M
authors.lastname: Dougados
authors.forename: M
authors.initials: M
authors.lastname: Schiff
authors.forename: J
authors.initials: J
authors.lastname: Smolen
authors.forename: D
authors.initials: D
authors.lastname: Aletaha
authors.forename: P L C M
authors.initials: PL
authors.lastname: van Riel
mesh_terms: D000069594:Abatacept; D000208:Acute Disease; D000328:Adult; D018501:Antirheumatic Agents / Q000627:therapeutic use*; D001172:Arthritis, Rheumatoid / Q000097:blood / Q000000981:diagnostic imaging / Q000188:drug therapy*; D001175:Arthrography; D015415:Biomarkers / Q000097:blood; D001799:Blood Sedimentation; D002097:C-Reactive Protein / Q000032:analysis; D017326:Clinical Trials, Phase III as Topic; D018450:Disease Progression; D005260:Female; D006801:Humans; D018796:Immunoconjugates / Q000627:therapeutic use*; D008297:Male; D008875:Middle Aged; D016032:Randomized Controlled Trials as Topic; D015203:Reproducibility of Results; D012720:Severity of Illness Index; D016896:Treatment Outcome
chemical_list: D018501:Antirheumatic Agents; D015415:Biomarkers; D018796:Immunoconjugates; D000069594:Abatacept; D002097:C-Reactive Protein