Background: Recent EULAR/PReS recommendations [1] have highlighted the need for a common way of assessing disease activity in the paediatric and adult patients affected by Still’s disease. The systemic Juvenile Arthritis Disease Activity Score (sJADAS) [2], validated in children, has a strong construct validity but has never been validated in adult patients.

Objectives: To evaluate the validity of sJADAS in adult patients with Still’s disease.

Methods: Retrospective analysis including adult patients with a diagnosis of Still’s disease, according to Yamaguchi’s or Fautrel’s classification criteria, seen in a tertiary center from 07.2016 to 09.2024. Patients with possible alternate diagnosis or missing clinical or laboratory data necessary to calculate the sJADAS were excluded. Next, patients were categorized by one investigator (GM) as being in inactive disease (ID), minimal disease activity (MDA), moderate disease activity (MoDA) or high disease activity (HDA), based on the definition proposed by Rosina et al (3). sJADAS was calculated for each patient and the proposed sJADAS cutoffs [3] of ID ≤2.9, MDA >2.9 to ≤10, MoDA from >10 to ≤20.6, and HDA >20.6 were used. Cohen’s kappa coefficient was used to evaluate the agreement between disease statuses according to sJADAS cutoffs and according to the physician rating based on the Rosina categorization.

Results: 125 visits from 91 patients were recorded. Most of the patients were women (n=66, 72.5%) with a mean (range) disease duration at visit of 6.4 (0-40) years. Anakinra was the most frequently used biological therapy (n=30 visits), followed by tocilizumab (n=14 visits) and canakinumab (n=9 visits). Methotrexate was used in 21 visits whereas glucocorticoids (GCs) in 45 visits. Patients did not receive any treatment in 41 visits. Mean (SD) sJADAS was 15.6 (13.1). Patients were in HDA in 41, in MDA in 29,in LDA in 28 and in ID in 27 visits, according to their sJADAS whereas they were in HDA in 37, in MoDA in 32, in MDA in 18 and in ID in 38 visits, according to the physician’s rating, respectively. Overall accuracy of sJADAS was 0.78 (95% CI: 0.69-0.85), whereas kappa coefficient was 0.7, indicating a substantial agreement between disease activity based on sJADAS cutoffs and physician-based disease activity. Detailed results per disease activity status are shown in Figure 1. sJADAS exhibited high specificity (range 86.9 to 97.7) across all disease activity statuses (Table 1), with the highest sensitivity for HDA. Positive predictive value (PPV) was reliable (range 75.9 to 92.6) except for LDA (50%), whereas negative predictive value was high for all patients (86.7-98.8%), resulting in overall high accuracy.

Conclusion: sJADAS may be a valuable tool for the assessment of disease activity in adult patients with Still’s disease and may be used to guide therapeutic decisions. Larger studies are needed to validate its use in clinical practice.

REFERENCES: [1] Fautrel B, Mitrovic S, De Matteis A, et al EULAR/PReS recommendations for the diagnosis and management of Still’s disease, comprising systemic juvenile idiopathic arthritis and adult-onset Still’s disease Annals of the Rheumatic Diseases 2024;83:1614-1627.

[2] Tibaldi J, Pistorio A, Aldera E, et al Development and initial validation of a composite disease activity score for systemic juvenile idiopathic arthritis. Rheumatology (Oxford). 2020 Nov 1;59(11):3505-3514.

[3] Rosina S, Rebollo-Giménez AI, Tarantola L, et al Defining Criteria for Disease Activity States in Systemic Juvenile Idiopathic Arthritis Based on the Systemic Juvenile Arthritis Disease Activity Score. Arthritis Rheumatol. 2024 Sep;76(9):1446-1454.

Acknowledgements: NIL.

Disclosure of Interests: None declared.

© The Authors 2025. This abstract is an open access article published in Annals of Rheumatic Diseases under the CC BY-NC-ND license ( http://creativecommons.org/licenses/by-nc-nd/4.0/ ). Neither EULAR nor the publisher make any representation as to the accuracy of the content. The authors are solely responsible for the content in their abstract including accuracy of the facts, statements, results, conclusion, citing resources etc.