Final validation of a new composite disease activity score for juvenile idiopathic arthritis: the Juvenile Arthritis Disease Activity Score (JADAS) by Consolaro A, Ruperto N, Bazso A, Magni-Manzoni S, Pelagatti MA, Pistorio A, Magnani A, Malattia C, D'Agostino I, Filocamo G, Martini A, Ravelli A