French protocol for the diagnosis and management of juvenile idiopathic arthritis including pediatric-onset Still's disease

Abstract

Juvenile idiopathic arthritis (JIA) is characterised by arthritis onset before the age of 16, persisting for at least 6weeks without a known cause. Symptoms include joint swelling, inflammatory pain (worse at night and in the morning), or also back, heel, or buttock pain. Timely diagnosis and referral to a paediatric rheumatologist are crucial to reduce errors, invasive procedures, and long-term complications. Around 5000 children under 16 are affected by JIA in France. The current international classification recognises 7 subgroups: the systemic form, oligoarthritis, polyarthritis without rheumatoid factor, polyarthritis with rheumatoid factor (juvenile rheumatoid arthritis), enthesitis associated with JIA (juvenile spondyloarthropathy), JIA associated with psoriasis and undifferentiated JIA. A new classification divides JIA into 5 groups: the systemic form, early-onset oligo- and polyarthritis with anti-nuclear antibodies (associated with a risk of chronic anterior uveitis), polyarthritis with rheumatoid factor, juvenile spondyloarthropathy and non-groupable forms. JIA management involves a multidisciplinary team led by a paediatric rheumatologist, using targeted therapies (biologics, small molecules) and numerous health professionals (physiotherapist, occupational therapist, etc.), improving overall outcomes. Physicians (paediatricians or general practitioners) play a vital role in overall management, ensuring treatment compliance, monitoring effectiveness, and managing infection risks. This includes updating vaccination schedules and addressing febrile episodes. We present recent international recommendations including the "treat-to-target" approach, consisting in setting precise objectives at the beginning and during the evolution, which involves regularly assessing the patient's situation to adapt treatments, control inflammation and disease complications, limit the toxicity of treatments. This strategy aims to achieve, ideally in a few months an inactive disease or complete remission. Regarding systemic JIA (or pediatric Still's disease), we pay attention to particularly severe clinical forms in very young children, which may be life-threatening by major activation of the immune system (macrophage activation syndrome) or secondary pulmonary involvement. For non-systemic forms, i.e. oligoarthritis, polyarthritis, enthesitis related JIA (or juvenile spondylarthropathies) and JIA associated with psoriasis, we specify the state of current knowledge and uncertainties regarding prognosis and therapeutic choices.

Keywords: Arthrite juvénile idiopathique; Biologics; Biologiques; Juvenile idiopathic arthritis; Maladie de Still à début pédiatrique; Methotrexate; Méthotrexate; Pediatric-onset Still's disease; Psoriasis; Uveitis; Uvéites.