title: Definition of improvement in juvenile idiopathic arthritis using the juvenile arthritis disease activity score.
abstract: OBJECTIVE
  The aim of this study was to define improvement thresholds for the Juvenile Arthritis Disease Activity Score (JADAS).
  
  
  METHODS
  Physicians' and parents' judgements on treatment efficacy, the ACR paediatric response measure (PedACR) and JADAS were extracted from BIKER. Patients were categorized by baseline classes in the 10-joint JADAS (JADAS10) as low (5 to <15), moderate (15 to <25) and high (25 to ≤40). Cut-offs for defining improvement following treatment with biologics or MTX were chosen by calculating the interquartile ranges (IQRs) of the judgement groups and considering the accuracy, sensitivity and specificity of the resulting model. Differences in the change of JADAS10 by JIA category were also analysed by analysis of variance (ANOVA). Sensitivity, specificity and accuracy were calculated.
  
  
  RESULTS
  A total of 1315 treatment courses were analysed. The ANOVA of the JIA categories showed no significant differences of the mean JADAS10 in all baseline classes and IQRs also showed good overall limits. Therefore all JIA categories were combined for a collective cut-off. Analysis by baseline class revealed clear cut-off points. Improvement could be defined by the minimal decrease in the JADAS10 in baseline class low by 4 (41%), moderate by 10 (53%) and high by 17 (57%). The model shows values for accuracy from 75.6 to 85.5% and comparable values for sensitivity and specificity.
  
  
  CONCLUSIONS
  Improvement after 3 months can be defined efficiently by the decrease of the JADAS10, depending on the baseline JADAS10 score, which specifies low, moderate or high disease activity. Our model demonstrates clear cut-off values. The JADAS10 may be used in addition to ACR criteria in clinical trials. Also, since the JADAS10 can easily be calculated at each patient visit, it also can be used for clinical decisions.
authors.affiliation: Centre of Paediatric Rheumatology, Department of General Paediatrics, Asklepios Clinic Sankt Augustin, Sankt Augustin and Department of Informatics and Epidemiology, Institute of Medical Statistics, University of Cologne, Cologne, Germany. g.horneff@asklepios.com.
authors.forename: Gerd
authors.initials: G
authors.lastname: Horneff
authors.affiliation: Centre of Paediatric Rheumatology, Department of General Paediatrics, Asklepios Clinic Sankt Augustin, Sankt Augustin and Department of Informatics and Epidemiology, Institute of Medical Statistics, University of Cologne, Cologne, Germany.
authors.forename: Ingrid
authors.initials: I
authors.lastname: Becker
mesh_terms: D000293:Adolescent; D018501:Antirheumatic Agents / Q000627:therapeutic use*; D001171:Arthritis, Juvenile / Q000628:therapy*; D001688:Biological Products / Q000627:therapeutic use; D002648:Child; D018450:Disease Progression; D005260:Female; D005858:Germany; D006801:Humans; D008297:Male; D008727:Methotrexate / Q000627:therapeutic use; D017063:Outcome Assessment, Health Care / Q000592:standards*; D012042:Registries; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D012720:Severity of Illness Index; D016896:Treatment Outcome
chemical_list: D018501:Antirheumatic Agents; D001688:Biological Products; D008727:Methotrexate
keywords: ACR; JADAS; definition of improvement; juvenile idiopathic arthritis; response parameters