Development and Initial Validation of the Systemic JADAS, a New Composite Disease Activity Score for Systemic Juvenile Idiopathic Arthritis

Background Juvenile Arthritis Disease Activity Score (JADAS) has gained increasing popularity for the measurement of the level of disease activity in patients with juvenile idiopathic arthritis (JIA). However, so far the JADAS has been validated only in children with the non-systemic categories of JIA. Objectives To develop and validate the systemic JADAS (sJADAS), a new version of the JADAS specific to systemic JIA (sJIA). Methods The sJADAS is made up by adding a fifth item, named Systemic Manifestation Score (SMS), to the four items included in the original tool (physician global assessment of disease activity, parent/patient global assessment of well-being, active joint count and erythrocyte sedimentation rate). The SMS ranges from 0 to 10 and is aimed to quantify the activity of systemic features. The sJADAS score ranges from 0 to 50. The validation sample included patients with definite and possible/probable sJIA with active systemic manifestations, which should comprise fever, who were assessed at baseline and then at a subsequent visit, 2 weeks to 3 months after initial evaluation. Validation procedures included assessment of concurrent, construct and discriminant validity, internal consistency and responsiveness to clinical change. Results A total of 161 patients, 86.7% (n=137) with definite sJIA and 13.3% (n=21) with possible/probable sJIA, assessed at disease onset (n=90; 56.6%) or at time of a disease flare (n=69; 43.4%), were enrolled at 57 centers in 10 countries from February 2017 to December 2018. Median age at disease onset was 5.0 years (interquartile range, IQR 2.8 - 8) and median age at study entry was 6.9 years (IQR 3.8–10.8). Median disease duration from onset to study entry was 0.2 years (IQR 0.1–1.9). The median sJADAS at baseline visit was 28.2 (IQR 22.8–35.0). The sJADAS correlated strongly with JADAS10 (rs=0.98) and clinical JADAS10 (cJADAS10) (rs=0.91); moderately with functional ability scales (JAFS and CHAQ) (rs=0.69; rs=0.62) and total score (rs=0.57) and physical (rs=0.60) and psychosocial (rs=0.40) subscale scores of the health-related quality of life tool (PRQL) and with pain VAS (rs=0.57); and mildly with the CRP (rs=0.42). The sJADAS discriminated well between patients with or without morning stiffness (p Conclusion The sJADAS was found to be a valid instrument for the assessment of disease activity in sJIA. This composite score is feasible and easily applicable in standard clinical practice, which should result in its widespread acceptance and use. The strong responsiveness to clinical change over time indicates that the sJADAS is suitable to assess therapeutic response in sJIA clinical trials. Disclosure of Interests Jessica Tibaldi: None declared, Yasser El Miedany: None declared, Priyankar Pal : None declared, Soamarat Vilaiyuk: None declared, Raju Khubchandani: None declared, Claudia Bracaglia: None declared, Tapas K Sabui : None declared, Sujata Sawhney: None declared, Riccardo Russo Speakers bureau: Novartis, Abbvie, Flavio R. Sztajnbok: None declared, Rolando Cimaz: None declared, Francesca Minoia: None declared, Motasem O. Alsuweiti: None declared, Ekaterina Alexeeva: None declared, Mikhail Kostik: None declared, Maria Cristina Maggio: None declared, Nicolino Ruperto Grant/research support from: The Gaslini Hospital, where NR works as full-time public employee, has received contributions (> 10.000 USD each) from the following industries in the last 3 years: BMS, Eli-Lilly, GlaxoSmithKline, F Hoffmann-La Roche, Janssen, Novartis, Pfizer, Sobi. This funding has been reinvested for the research activities of the hospital in a fully independent manner, without any commitment with third parties., Consultant for: Received honoraria for consultancies or speaker bureaus (