title: Disease activity score 28 as an instrument to measure disease activity in patients with early rheumatoid arthritis.
abstract: OBJECTIVE
  To examine the influence of components of the Disease Activity Score 28 (DAS28) [tender joint count (TJC), swollen joint count (SJC), patient's general health (GH), and erythrocyte sedimentation rate (ESR)] on the total DAS28 score, and overlapping of the 4 individual components in rheumatoid arthritis (RA) patients with low, moderate, or high disease activity.
  
  
  METHODS
  The effect of each component was studied in the FIN-RACo trial patients at 6 months and in a "theoretical model," where each component of the DAS28 ranged as follows: TJC and SJC from 0 to 28, GH from 0 to 100, and ESR from 1 to 100, while the other 3 components were 0 (ESR1). Overlapping of the components was studied in the FIN-RACo trial patients at 6 months with low (DAS28 < or = 3.2), moderate (DAS28 > 3.2 and < or = 5.1), and high (DAS28 > 5.1) disease activity. The higher limit for overlapping was defined as the highest SJC in the low disease activity group, and the lower limit as the lowest SJC in the high disease activity group; the percentage of patients who fall between these limits represent overlapping in SJC. Overlapping was calculated similarly concerning TJC, ESR, and GH.
  
  
  RESULTS
  ESR had the greatest effect on DAS28, followed by TJC, GH, and SJC, while in the "theoretical model" TJC had the greatest effect on the DAS28, followed by ESR, SJC, and GH. At 6 months, overlapping was present in 54%, 45%, 49%, and 31% of patients in SJC, TJC, GH, and ESR, respectively.
  
  
  CONCLUSIONS
  In real-life patients, ESR had the greatest effect of the 4 components of DAS28 on the total DAS28 score. The values of the individual components of DAS28 overlap considerably among the 3 disease activity groups.
authors.affiliation: Jyväskylä Central Hospital, Jyväskylä, Finland. heidi.makinen@ksshp.fi
authors.forename: Heidi
authors.initials: H
authors.lastname: Mäkinen
authors.forename: Hannu
authors.initials: H
authors.lastname: Kautiainen
authors.forename: Pekka
authors.initials: P
authors.lastname: Hannonen
authors.forename: Timo
authors.initials: T
authors.lastname: Möttönen
authors.forename: Markku
authors.initials: M
authors.lastname: Korpela
authors.forename: Marjatta
authors.initials: M
authors.lastname: Leirisalo-Repo
authors.forename: Reijo
authors.initials: R
authors.lastname: Luukkainen
authors.forename: Kari
authors.initials: K
authors.lastname: Puolakka
authors.forename: Anna
authors.initials: A
authors.lastname: Karjalainen
authors.forename: Tuulikki
authors.initials: T
authors.lastname: Sokka
mesh_terms: D001172:Arthritis, Rheumatoid / Q000473:pathology / Q000503:physiopathology; D004185:Disability Evaluation; D018450:Disease Progression; D006801:Humans; D012107:Research Design; D012720:Severity of Illness Index