title: Comparison of the DAS28-CRP and DAS28-ESR in patients with rheumatoid arthritis.
abstract: OBJECTIVE
  To compare the Disease Activity Score with 28 joint (DAS28) using erythrocyte sedimentation rate (ESR) (DAS28-ESR) and DAS28 using C-reactive protein (CRP) (DAS28-CRP) with thresholds validated for DAS28-ESR in Turkish patients with rheumatoid arthritis.
  
  
  METHODS
  The DAS28 data of 112 patients with rheumatoid arthritis followed in a local outpatient clinic were used. First, the correlation between DAS28-CRP and DAS28-ESR and the correlation between their unique components ([0.36 × In (CRP + 1) + 0.96] and [0.70 × In (ESR)]) were analyzed. Second, a Bland-Altman plot was constructed for the evaluation of the level of agreement between DAS28-CRP and DAS28-ESR. Lastly, the agreement between these two methods was analyzed by κ coefficient.
  
  
  RESULTS
  Although there was a strong correlation between DAS28-CRP and DAS28-ESR, the correlation between their unique components was fair. Although more than 95% of the point data fall between the upper and lower bounds of the limit of agreement, the percentage error (46%) was higher than the acceptable proportion of 30%. The κ coefficient of agreement between DAS28- ESR and DAS28-CRP with validated thresholds for DAS28-ESR was 0.42, which was close to the lower boundary for moderate agreement.
  
  
  CONCLUSIONS
  The results of this study demonstrated that there is discordance between DAS28-ESR and DAS28-CRP with the validated thresholds for DAS28-ESR. Using the DAS28-CRP with threshold values validated for DAS28-ESR may lead to errors in the determination of disease activity and therefore may lead to errors in the management of patients with rheumatoid arthritis.
authors.affiliation: Department of Physical Medicine and Rehabilitation, Izmir Bozyaka Training and Research Hospital, Izmir, Turkey.
authors.forename: Ilker
authors.initials: I
authors.lastname: Sengul
authors.affiliation: Department of Physical Medicine and Rehabilitation, Izmir Bozyaka Training and Research Hospital, Izmir, Turkey.
authors.forename: Seniz
authors.initials: S
authors.lastname: Akcay-Yalbuzdag
authors.affiliation: Department of Physical Medicine and Rehabilitation, Izmir Bozyaka Training and Research Hospital, Izmir, Turkey.
authors.forename: Bugra
authors.initials: B
authors.lastname: Ince
authors.affiliation: Department of Physical Medicine and Rehabilitation, Izmir Bozyaka Training and Research Hospital, Izmir, Turkey.
authors.forename: Altinay
authors.initials: A
authors.lastname: Goksel-Karatepe
authors.affiliation: Department of Physical Medicine and Rehabilitation, Izmir Bozyaka Training and Research Hospital, Izmir, Turkey.
authors.forename: Taciser
authors.initials: T
authors.lastname: Kaya
mesh_terms: D000328:Adult; D000368:Aged; D018501:Antirheumatic Agents / Q000627:therapeutic use; D001172:Arthritis, Rheumatoid / Q000097:blood / Q000175:diagnosis* / Q000188:drug therapy / Q000276:immunology; D015415:Biomarkers / Q000097:blood; D001799:Blood Sedimentation; D002097:C-Reactive Protein / Q000032:analysis*; D005260:Female; D006801:Humans; D018836:Inflammation Mediators / Q000097:blood*; D008297:Male; D008875:Middle Aged; D010044:Outpatient Clinics, Hospital; D011237:Predictive Value of Tests; D012074:Remission Induction; D015203:Reproducibility of Results; D012720:Severity of Illness Index; D013997:Time Factors; D016896:Treatment Outcome; D014421:Turkey
chemical_list: D018501:Antirheumatic Agents; D015415:Biomarkers; D018836:Inflammation Mediators; D002097:C-Reactive Protein
keywords: C-reactive protein; DAS28; erythrocyte sedimentation rate; rheumatoid arthritis