title: Development and validation of a preliminary definition of minimal disease activity in patients with juvenile idiopathic arthritis.
abstract: OBJECTIVE
  To develop and validate a definition of minimal disease activity (MDA) in patients with juvenile idiopathic arthritis (JIA).
  
  
  METHODS
  The clinical charts of JIA patients followed over a 16-year period were reviewed to identify visits with high disease activity and MDA, defined on the basis of therapeutic decisions made by the attending physician. For each JIA activity measure recorded at the time of the visit, the cutoff value that best identified states of MDA was calculated by means of the area under the receiver operating characteristic curve analysis. A definition of MDA for oligoarthritis and polyarthritis was set up after testing the relative power of each variable in a multivariate analysis. Validation procedures included assessment of discriminant and construct validity.
  
  
  RESULTS
  The definition that resulted from the analyses led to establish that a state of MDA could be defined as the presence of a physician global assessment < or =2.5 cm and a swollen joint count of 0 in patients with oligoarthritis; and as the presence of a physician global assessment < or =3.4 cm, a parent global assessment < or =2.1 cm, and a swollen joint count < or =1 in patients with polyarthritis. Validation procedures demonstrated that the MDA definition had good discriminant and construct validity in the context of both observational studies and controlled trials.
  
  
  CONCLUSIONS
  We developed a preliminary definition of MDA in patients with JIA that represents a useful treatment target state and is proposed for inclusion as an outcome measure in future observational studies and clinical trials in patients with JIA.
authors.affiliation: Fondazione Istituto di Ricovero e Cura a Carattere Scientifico Policlinico S. Matteo, Pavia, Italy.
authors.forename: Silvia
authors.initials: S
authors.lastname: Magni-Manzoni
authors.forename: Nicolino
authors.initials: N
authors.lastname: Ruperto
authors.forename: Angela
authors.initials: A
authors.lastname: Pistorio
authors.forename: Elena
authors.initials: E
authors.lastname: Sala
authors.forename: Nicoletta
authors.initials: N
authors.lastname: Solari
authors.forename: Elena
authors.initials: E
authors.lastname: Palmisani
authors.forename: Chiara
authors.initials: C
authors.lastname: Cugno
authors.forename: Elena
authors.initials: E
authors.lastname: Bozzola
authors.forename: Alberto
authors.initials: A
authors.lastname: Martini
authors.forename: Angelo
authors.initials: A
authors.lastname: Ravelli
mesh_terms: D018501:Antirheumatic Agents / Q000627:therapeutic use; D001171:Arthritis, Juvenile / Q000188:drug therapy / Q000473:pathology* / Q000503:physiopathology*; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007223:Infant; D007596:Joints / Q000473:pathology*; D008297:Male; D015999:Multivariate Analysis; D012372:ROC Curve; D015203:Reproducibility of Results; D012720:Severity of Illness Index
chemical_list: D018501:Antirheumatic Agents