The Paediatric Rheumatology International Trials Organisation provisional criteria for the evaluation of response to therapy in juvenile dermatomyositis.
OBJECTIVE
To develop a provisional definition for the evaluation of response to therapy in juvenile dermatomyositis (DM) based on the Paediatric Rheumatology International Trials Organisation juvenile DM core set of variables.


METHODS
Thirty-seven experienced pediatric rheumatologists from 27 countries achieved consensus on 128 difficult patient profiles as clinically improved or not improved using a stepwise approach (patient's rating, statistical analysis, definition selection). Using the physicians' consensus ratings as the "gold standard measure," chi-square, sensitivity, specificity, false-positive and-negative rates, area under the receiver operating characteristic curve, and kappa agreement for candidate definitions of improvement were calculated. Definitions with kappa values >0.8 were multiplied by the face validity score to select the top definitions.


RESULTS
The top definition of improvement was at least 20% improvement from baseline in 3 of 6 core set variables with no more than 1 of the remaining worsening by more than 30%, which cannot be muscle strength. The second-highest scoring definition was at least 20% improvement from baseline in 3 of 6 core set variables with no more than 2 of the remaining worsening by more than 25%, which cannot be muscle strength (definition P1 selected by the International Myositis Assessment and Clinical Studies group). The third is similar to the second with the maximum amount of worsening set to 30%. This indicates convergent validity of the process.


CONCLUSIONS
We propose a provisional data-driven definition of improvement that reflects well the consensus rating of experienced clinicians, which incorporates clinically meaningful change in core set variables in a composite end point for the evaluation of global response to therapy in juvenile DM.
Ruperto
Nicolino
N
Paediatric Rheumatology International Trials Organisation, Genoa, Italy. nicolaruperto@ospedale-gaslini.ge.it
Pistorio
Angela
A
Ravelli
Angelo
A
Rider
Lisa G
LG
Pilkington
Clarissa
C
Oliveira
Sheila
S
Wulffraat
Nico
N
Espada
Graciela
G
Garay
Stella
S
Cuttica
Ruben
R
Hofer
Michael
M
Quartier
Pierre
P
Melo-Gomes
Jose
J
Reed
Ann M
AM
Wierzbowska
Malgorzata
M
Feldman
Brian M
BM
Harjacek
Miroslav
M
Huppertz
Hans-Iko
HI
Nielsen
Susan
S
Flato
Berit
B
Lahdenne
Pekka
P
Michels
Harmut
H
Murray
Kevin J
KJ
Punaro
Lynn
L
Rennebohm
Robert
R
Russo
Ricardo
R
Balogh
Zsolt
Z
Rooney
Madeleine
M
Pachman
Lauren M
LM
Wallace
Carol
C
Hashkes
Philip
P
Lovell
Daniel J
DJ
Giannini
Edward H
EH
Gare
Boel Andersson
BA
Martini
Alberto
A
D002648:Child; D002675:Child, Preschool; D002986:Clinical Trials as Topic / Q000592:standards*; D003882:Dermatomyositis / Q000453:epidemiology / Q000628:therapy; D005260:Female; D006801:Humans; D038622:Internationality; D008297:Male; D010372:Pediatrics / Q000592:standards*; D015203:Reproducibility of Results; D012219:Rheumatology / Q000592:standards*; D016896:Treatment Outcome