E08 Single center study of Systemic Juvenile Idiopathic Arthritis in Moroccan patients

Abstract

Abstract Introduction Juvenile idiopathic arthritis (JIA) is the most common rheumatological disorder in childhood. About 10% to 20% of children with JIA have a rare and serious subtype called systemic juvenile idiopathic arthritis (SJIA). SJIA differs from other subtypes in that it’s the only one considered an autoinflammatory rather than autoimmune disease because of the association with systemic features and is therefore treated differently with anti-IL1 and anti-IL6. Objectives To describe epidemiological data of SJIA in Moroccan patients taking into account environmental conditions. To compare existing criteria (ILAR, Fautrel, Yamaguchi) to the new Pediatric Rheumatology International Trials Organization (PRINTO) classification currently in the process of validation. Patient and methods Retrospective prospective study conducted between January 2019 and December 2022. SJIA was diagnosed based on one of the four classification criteria ILAR, Fautrel, Yamaguchi or PRINTO Classification after ruling out infectious disease, immunodeficiency and malignancy whenever necessary. Complete remission was defined as the absence of clinical signs and inflammatory syndrome. Partial remission was defined as the absence of active clinical signs with persistence of inflammatory syndrome. Results Nine SIJA (44% male) patients were enrolled. The mean age at diagnosis was 4 years 8 months, the mean time to diagnosis was 4.8 months (range 1 – 24 months), the average follow up period was 16.4 months. At the time of diagnosis, the most common findings were typical fever (100%), arthritis (66%), skin rash (55%), 2 patients had pericarditis and one had macrophage activation syndrome (MAS), there was no renal or pulmonary involvement. Laboratory data showed in all patients, high level of C-reactive protein at mean value of 183 mg/l, increased erythrocyte sedimentation rate at mean of 88 mm first h, hyperleukocytosis at mean of 17 000 WBC/mm3 with high neutrophil counts at a mean of 12 297/mm3 and thrombocytosis at a mean of 625 000/mm3. To rule out other diagnosis, para clinical evaluation showed a positive antinuclear antibody in one patient without pathogenic significance, a bone marrow count performed in 3 patients, showed normal count in 2 patients and hemophagocytosis in one patient and immunoglobulins assay performed in 3 patients was normal. Of the 9 patients, 4 met all the criteria, 2 were diagnosed based on Yamaguchi criteria and one on Fautrel criteria, one fulfilled all criteria except ILAR and the last fulfilled only ILAR and new PRINTO classification. One patient was treated with corticosteroid pulse therapy for MAS and then oral corticosteroids with complete remission. Another received corticosteroids and biotherapy [tocilizumab (TCZ)] upfront due to late consultation and severe form with complete remission. Seven patients were treated with non-steroidal anti-inflammatory drugs (NSAIDs) of which one achieved partial remission with a delay of 2 months of follow up and 6 required adjunctions of another medication: corticosteroids (4), MTX (2), biotherapy (5) [anakinra (5), Switch TCZ (2)] with complete remission. The last patient reached complete remission under corticosteroids, Triamcinolone Hexacetonide knee infiltration and methotrexate. Anakinra was the most common first-line biologic treatment choice (n = 5), and 2 of them need switch to Tocilizumab to achieve remission. One of the 2 patients with pericarditis needed a rescue drainage. Outcome was favorable in all patients except one who had a relapse with final remission, and articular sequel in 3 patients. Discussion and conclusion SJIA is a rare but serious condition with high risk of morbidity related to arthritis and mortality from MAS and pericarditis. The latter features turn into a good prognosis with early diagnosis and treatment, as we have done. It can occur any time during childhood, but it most commonly starts at around the age of two years, unlike our patients who were older. No predominance ratio is reported as we have noted. SJIA is referred to as Still disease by some authors justifying the new PRINTO classification and the specific treatment. In our study, Yamaguchi criteria seem to be the most sensitive (7/9 fulfilled) followed by New PRINTO classification and Fautrel criteria (6/9 fulfilled), ILAR criteria are the less sensitive (5/9 fulfilled) what can delay diagnosis and treatment. Our study showed the benefit of biological agent, 66% of patients achieved remission with at least one biological agent and we concluded that Anti-IL1 drugs are mostly preferred for ongoing systemic inflammation. However Anti-IL-6 agents are very efficient in patients with a polyarticular course.