Development and validation of a preliminary definition of minimal disease activity in patients with juvenile idiopathic arthritis.
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.
Magni-Manzoni
Silvia
S
Fondazione Istituto di Ricovero e Cura a Carattere Scientifico Policlinico S. Matteo, Pavia, Italy.
Ruperto
Nicolino
N
Pistorio
Angela
A
Sala
Elena
E
Solari
Nicoletta
N
Palmisani
Elena
E
Cugno
Chiara
C
Bozzola
Elena
E
Martini
Alberto
A
Ravelli
Angelo
A
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
D018501:Antirheumatic Agents