Defining Criteria for Disease Activity States in Nonsystemic Juvenile Idiopathic Arthritis Based on a Three-Variable Juvenile Arthritis Disease Activity Score ALESSANDRO CONSOLARO, 1 GIORGIA NEGRO, 1 MARIA CHIARA GALLO, 1 GIULIA BRACCIOLINI, 1 CRISTINA FERRARI, 1 BENEDETTA SCHIAPPAPIETRA, 1 ANGELA PISTORIO, 1 FRANCESCA BOVIS, 1 NICOLINO RUPERTO, 1 ALBERTO MARTINI, 2 AND ANGELO RAVELLI 2 Objective. To determine cutoff values for defining the states of inactive disease (ID), low disease activity (LDA; or minimal disease activity), moderate disease activity (MDA), and high disease activity (HDA) using the clinical (3-variable) Juvenile Arthritis Disease Activity Score (cJADAS). Methods. For selection of cutoffs, data from a clinical database including 609 children with juvenile idiopathic arthritis (JIA) were used. Optimal cutoffs were determined against external criteria by calculating the 75th and 90th percentile (for ID and LDA) and 10th and 25th percentile (for HDA) of cumulative score distribution and through receiver operating characteristic curve analysis. External criteria included definitions for ID and LDA cutoffs and therapeutic decisions for HDA cutoffs. MDA cutoffs were set at the score interval in-between LDA and HDA cutoffs. Crossvalidation was performed using 2 JIA patient samples (n  485) and was based on assessment of construct and discriminant validity. Results. The selected cutoffs were as follows: <1 for ID in both oligoarthritis and polyarthritis; <1.5 and <2.5 for LDA in oligoarthritis and polyarthritis, respectively; 1.51– 4 and 2.51– 8.5 for MDA in oligoarthritis and polyarthritis, respec- tively; and >4 and >8.5 for HDA in oligoarthritis and polyarthritis, respectively. In crossvalidation analyses, the cutoffs showed a strong ability to discriminate between disease activity states defined subjectively by physicians and parents, levels of pain, and presence/absence of functional impairment and disease damage. Conclusion. Cutoff values for classifying various disease states in nonsystemic JIA using the cJADAS were developed. The cutoffs revealed good measurement characteristics in crossvalidation analyses and are suited for application in clinical practice and research. INTRODUCTION Juvenile idiopathic arthritis (JIA) is an umbrella term that encompasses all forms of arthritis that begin before the age of 16 years, persist for 6 weeks, and are of unknown origin (1,2). The natural history of the disease is charac- terized by frequent fluctuation of activity over time. Reg- ular measurement of the level of disease activity is funda- mental to improving outcome, because uncontrolled active disease plays a major role in causing joint damage and associated physical functional disability. However, be- cause of the heterogeneity in the clinical presentation and course of JIA, no single measure can reliably capture over- all disease activity in all patients. Conversely, evaluation of all measures individually is associated with method- ological and statistical problems. These drawbacks can be overcome with the use of the so-called composite disease activity scores. These tools are made up by pooling individual measures of disease activ- ity in a single instrument and allow the integration of various aspects of the disease into 1 summary number on a continuous scale (3). Recently, the first composite dis- ease activity score for JIA, termed the Juvenile Arthritis Disease Activity Score (JADAS), has been reported. The JADAS consists of 4 variables: physician’s global rating of 1 Alessandro Consolaro, MD, PhD, Giorgia Negro, MD, Maria Chiara Gallo, MD, Giulia Bracciolini, MD, Cristina Ferrari, MD, Benedetta Schiappapietra, MD, Angela Pistorio, MD, PhD, Francesca Bovis, BiolD, Nicolino Ruperto, MD, MPH: Istituto Giannina Gaslini, Genoa, Italy; 2 Alberto Martini, MD, Angelo Ravelli, MD: Istituto Gian- nina Gaslini and Universita` degli Studi di Genova, Genoa, Italy. Address correspondence to Alessandro Consolaro, MD, PhD, Pediatria II–Reumatologia, Istituto G. Gaslini, Largo G. Gaslini 5, 16147 Genoa, Italy. E-mail: alessandroconsol aro@ospedale-gaslini.ge.it. Submitted for publication March 12, 2014; accepted in revised form June 24, 2014. Arthritis Care & Research Vol. 66, No. 11, November 2014, pp 1703–1709 DOI 10.1002/acr.22393 © 2014, American College of Rheumatology ORIGINAL ARTICLE 1703