title: Correlation of rheumatoid arthritis activity indexes (Disease Activity Score 28 measured with ESR and CRP, Simplified Disease Activity Index and Clinical Disease Activity Index) and agreement of disease activity states with various cut-off points in a Northeastern Brazilian population.
abstract: BACKGROUND
  The Disease Activity Score 28 (DAS28) and its versions have been used to measure rheumatoid arthritis (RA) activity, but there is no consensus about which one is the best.
  
  
  OBJECTIVE
  Determine the correlation among indexes (DAS28 ESR, DAS28 CRP, SDAI and CDAI) and evaluate agreement of activity strata using different cutoff points.
  
  
  METHODS
  Rheumatoid arthritis patients were cross-sectionally evaluated with data collection to calculate the DAS28 (ESR and CRP), SDAI and CDAI, using different cut-offs for defining remission, mild, moderate and high activity. Pearson correlations were calculated for continuous measures and agreement (kappa test) for the strata (remission, mild, moderate and high activity).
  
  
  RESULTS
  Of 111 patients included, 108 were women, age 55.6 years, 11-year disease duration. DAS28 (ESR) was significantly higher than DAS28 (CRP) (4.0 vs. 3.5; p<0.001) and the values remained higher after stratification by age, gender, disease duration, rheumatoid factor and HAQ. Correlations among indexes ranged from 0.84 to 0.99, with better correlation between SDAI and CDAI. Agreements among activity strata ranged from 46.8% to 95.8%. DAS28 (CRP) with cut-off point for the remission of 2.3 underestimated disease activity by 45.8% compared with DAS28 (ESR). SDAI and CDAI showed agreement of 95.8%. The four indexes were associated with disease duration and HAQ.
  
  
  CONCLUSIONS
  Although the activity indexes show good correlation, they show discrepancies in activity strata, thus requiring more researches to define a better index and better cutoff points.
authors.affiliation: Faculdade de Medicina, Universidade Federal do Ceará, Fortaleza, CE, Brasil. Electronic address: mmcmedeiros@hotmail.com.
authors.forename: Marta Maria das Chagas
authors.initials: MM
authors.lastname: Medeiros
authors.affiliation: Hospital Universitário Walter Cantídio, Fortaleza, CE, Brasil.
authors.forename: Brenda Maria Gurgel Barreto
authors.initials: BM
authors.lastname: de Oliveira
authors.affiliation: Universidade de Fortaleza, Fortaleza, CE, Brasil.
authors.forename: João Victor Medeiros
authors.initials: JV
authors.lastname: de Cerqueira
authors.affiliation: Hospital Universitário Walter Cantídio, Fortaleza, CE, Brasil.
authors.forename: Raquel Telles de Souza
authors.initials: RT
authors.lastname: Quixadá
authors.affiliation: Hospital Universitário Walter Cantídio, Fortaleza, CE, Brasil.
authors.forename: Ídila Mont'Alverne Xavier
authors.initials: ÍM
authors.lastname: de Oliveira
mesh_terms: D001172:Arthritis, Rheumatoid / Q000503:physiopathology*; D001938:Brazil; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012720:Severity of Illness Index
keywords: Agreement; Artrite reumatoide; Atividade doença; Concordância; Correlation; Correlação; DAS28; Disease activity; Rheumatoid arthritis